The Roman Warm Period, or Roman Climatic Optimum, was a period of unusually warm weather in Europe and the North Atlantic that ran from approximately 250 BC to AD 400. Theophrastus (371 – c. 287 BC) wrote that date trees could grow in Greece if they were planted, but that they could not set fruit there. That is the case today, implying that South Aegean
mean summer temperatures in the 4th and 5th centuries BC were within a
degree of modern ones. That and other literary fragments from the time
confirm that the Greek climate then was basically the same as it was
around 2000. Tree rings from the Italian Peninsula in the late 3rd century BC indicate a time of mild conditions there at the time of Hannibal's crossing of the Alps with imported elephants (218 BC).
Dendrochronological evidence from wood found at the Parthenon shows variability of climate in the 5th century BC, which resembles the modern pattern of variation.
Cooling at the end of the period is noted in Southwest Florida.
This may have been due to a reduction in solar radiation reaching the
Earth, which may have triggered a change in atmospheric circulation
patterns.
The phrase "Roman Warm Period" appears in a 1995 doctoral thesis. It was popularized by an article published in Nature in 1999.
A high-resolution pollen analysis of a core from Galicia concluded in 2003 that the Roman Warm Period lasted from 250 BC to AD 450 in northwestern Iberia.
Glaciers
A
1986 analysis of Alpine glaciers concluded that the period AD 100–400
period was significantly warmer than centuries before and after. Artifacts recovered from the retreating Schnidejoch glacier have been taken as evidence for the Bronze Age, Roman, and Medieval Warm Periods.
Deep ocean sediment
A 1999 reconstruction of ocean current patterns, based on the granularity of deep ocean sediment, concluded that there was a Roman Warm Period, which peaked around AD 150.
Mollusk shells
An
analysis of oxygen isotopes found in mollusk shells in an Icelandic
inlet concluded in 2010 that Iceland experienced an exceptionally warm
period from 230 BC to AD 40.
Global average temperatures show that the Medieval Warm Period was not a planet-wide phenomenon.
The Medieval Warm Period (MWP) also known as the Medieval Climate Optimum, or Medieval Climatic Anomaly was a time of warm climate in the North Atlantic region lasting from c. 950 to c. 1250. It was likely related to warming elsewhere while some other regions were colder, such as the tropical Pacific.
Average global mean temperatures have been calculated to be similar to
early-mid-20th-century warming. Possible causes of the Medieval Warm
Period include increased solar activity, decreased volcanic activity,
and changes to ocean circulation.
The period was followed by a cooler period in the North Atlantic and elsewhere termed the Little Ice Age.
Some refer to the event as the Medieval Climatic Anomaly as this term
emphasizes that climatic effects other than temperature were important.
It is thought that between c. 950 and c. 1100 was the Northern Hemisphere's warmest period since the Roman Warm Period. It was only in the 20th and 21st centuries that the Northern Hemisphere experienced higher temperatures. Climate proxy
records show peak warmth occurred at different times for different
regions, indicating that the Medieval Warm Period was not a globally
uniform event.
Initial research
The Medieval Warm Period (MWP) is generally thought to have occurred from c. 950–c. 1250, during the European Middle Ages. In 1965 Hubert Lamb, one of the first paleoclimatologists, published research based on data from botany,
historical document research and meteorology, combined with records
indicating prevailing temperature and rainfall in England around c. 1200 and around c. 1600.
He proposed, "Evidence has been accumulating in many fields of
investigation pointing to a notably warm climate in many parts of the
world, that lasted a few centuries around c. 1000–c. 1200 AD, and was followed by a decline of temperature levels till between c. 1500 and c. 1700 the coldest phase since the last ice age occurred."
The warm period became known as the Medieval Warm Period, and the cold period was called the Little Ice Age (LIA). However, that view was questioned by other researchers; the IPCC First Assessment Report
of 1990 discussed the "Medieval Warm Period around 1000 AD (which may
not have been global) and the Little Ice Age which ended only in the
middle to late nineteenth century." It said temperatures in the "late
tenth to early thirteenth centuries (about AD 950-1250) appear to have
been exceptionally warm in western Europe, Iceland and Greenland". The IPCC Third Assessment Report
from 2001 summarized newer research: "evidence does not support
globally synchronous periods of anomalous cold or warmth over this time
frame, and the conventional terms of 'Little Ice Age' and 'Medieval Warm
Period' are chiefly documented in describing northern hemisphere trends
in hemispheric or global mean temperature changes in past centuries." Global temperature records taken from ice cores, tree rings,
and lake deposits, have shown that the Earth may have been slightly
cooler globally (by 0.03 °C) than in the early and mid-20th century.
Palaeoclimatologists developing region-specific climate
reconstructions of past centuries conventionally label their coldest
interval as "LIA" and their warmest interval as the "MWP."
Others follow the convention, and when a significant climate event is
found in the "LIA" or "MWP" time frames, they associate their events to
the period. Some "MWP" events are thus wet events or cold events rather
than strictly warm events, particularly in central Antarctica, where climate patterns opposite to the North Atlantic area have been noticed.
Globally
A 2009 study by Michael E. Mannet al., examining spatial patterns of surface temperatures shown in multi-proxy
reconstructions finds that the Medieval Warm Period, shows "warmth that
matches or exceeds that of the past decade in some regions, but which
falls well below recent levels globally." Their reconstruction of the pattern is characterised by warmth over a large part of the North Atlantic Ocean, Southern Greenland, the Eurasian Arctic, and parts of North America
which appears to substantially exceed that of the late 20th century
(1961–1990) baseline and is comparable or exceeds that of the past
decade or two in some regions. Certain regions, such as central Eurasia, northwestern North America, and (with less confidence) parts of the South Atlantic, exhibit anomalous coolness.
In 2013, a study by the Pages-2k consortium suggests the warming
was not globally synchronous: "Our regional temperature reconstructions
also show little evidence for globally synchronized multi-decadal shifts
that would mark well-defined worldwide MWP and LIA intervals. Instead,
the specific timing of peak warm and cold intervals varies regionally,
with multi-decadal variability resulting in regionally specific
temperature departures from an underlying global cooling trend."
In direct contrast to these findings, a 2013 study recreated a
"temperature record of western equatorial Pacific subsurface and
intermediate water masses over the past 10,000 years that shows that
heat content varied in step with both Northern and Southern
high-latitude oceans. The findings support the view that the Holocene
Thermal Maximum, the Medieval Warm Period, and the Little Ice Age were
global events, and they provide a long-term perspective for evaluating
the role of ocean heat content in various warming scenarios for the
future."
In 2019, using an extended proxy data set,
the Pages-2k consortium confirmed that the Medieval Climate Anomaly was
not a globally synchronous event. The warmest 51-year period within
'Medieval Warm Period' did not occur at the same time for different
regions. They argue for a regional instead of global framing of climate variability in the preindustrial Common Era to aid understanding.
North Atlantic
Greenland
ice sheet temperatures interpreted with 18O isotope from 6 ice cores
(Vinther, B., et al., 2009). The dataset ranges from 9690BC to AD1970
and it has a resolution of around 20 years, meaning that each data point
represents the average temperature of the surrounding 20 years.
The last written records of the Norse Greenlanders are from an Icelandic marriage in 1408 but recorded later in Iceland, at Hvalsey Church, now the best-preserved of the Norse ruins.
Lloyd D. Keigwin's 1996 study of radiocarbon-dated box core data from marine sediments in the Sargasso Sea
found that its sea surface temperature was approximately 1 °C (1.8 °F)
cooler approximately 400 years ago (the Little Ice Age) and 1700 years
ago and approximately 1 °C warmer 1000 years ago (the Medieval Warm
Period).
Using sediment samples from Puerto Rico, the Gulf Coast, and the Atlantic Coast from Florida to New England, Mann et al. (2009) found consistent evidence of a peak in North Atlantic tropical cyclone activity during the Medieval Warm Period that was followed by a subsequent lull in activity.
By retrieval and isotope analysis of marine cores and from examination of mollusc growth patterns from Iceland, Patterson et al were able to reconstruct a mollusc growth record at a decadal resolution from the Roman Warm Period to the Medieval Warm Period and the Little Ice Age.
North America
1690 copy of the 1570 Skálholt map, based on documentary information about earlier Norse sites in America.
The 2009 Mannet al. study found warmth exceeding 1961–1990 levels in Southern Greenland
and parts of North America during the Medieval Climate Anomaly (defined
in the study from 950 to 1250) with warmth in some regions exceeding
temperatures of the 1990–2010 period. Much of the Northern Hemisphere
showed significant cooling during the Little Ice Age (defined in the
study from 1400 to 1700), but Labrador and isolated parts of the United States appeared to be approximately as warm as during the 1961–1990 period.
Norse colonization of the Americas has been associated with warmer periods. The common theory is that Norsemen took advantage of ice-free seas to colonize areas in Greenland and other outlying lands of the far north. However a study from Columbia University suggests that Greenland was not colonized in warmer weather, but in fact the warming effect was very short term. c. 1000AD, the climate was sufficiently warm for the Vikings to journey to Newfoundland and establish a short-lived outpost there.
From around 985, Vikings founded the Eastern Settlement and Western Settlement,
both near the southern tip of Greenland. In the colony's early stages,
they kept cattle, sheep, and goats, with around a quarter of their diet
from seafood. After the climate became colder and stormier around 1250,
their diet steadily shifted towards ocean sources; by around 1300, seal hunting provided over three quarters of their food.
By 1350, there was reduced demand for their exports, and trade
with Europe fell away. The last document from the settlements dates from
1412, and over the following decades, the remaining Europeans left in
what seems to have been a gradual withdrawal, caused mainly by economic
factors such as increased availability of farms in Scandinavian
countries.
In Chesapeake Bay (now Maryland and Virginia
in the United States), researchers found large temperature excursions
(changes from the mean temperature of that time) during the Medieval
Warm Period (about 950–1250) and the Little Ice Age
(about 1400–1700, with cold periods persisting into the early 20th
century), possibly related to changes in the strength of North Atlantic thermohaline circulation. Sediments in Piermont Marsh of the lower Hudson Valley show a dry Medieval Warm period from 800 to 1300.
Prolonged droughts affected many parts of the western United States and especially eastern California and the west of Great Basin. Alaska experienced three time intervals of comparable warmth: 1–300, 850–1200, and post-1800.
Knowledge of the North American Medieval Warm Period has been useful in
dating occupancy periods of certain Native American habitation sites,
especially in arid parts of the western United States. MWP droughts may have also impacted Native American settlements in the eastern United States, such as at Cahokia.
Review of more recent archaeological research shows that as the search
for signs of unusual cultural changes has broadened, some of the early
patterns (for example, violence and health problems) having been found
to be more complicated and regionally varied than it had been previously
thought. Others, like settlement disruption, deterioration of
long-distance trade, and population movements, have been further
corroborated.
Africa
The climate in equatorial eastern Africa has alternated between drier than today and relatively wet. It was drier during the Medieval Warm Period (1000–1270).
Antarctica
A sediment core from the eastern Bransfield Basin, Antarctic Peninsula,
preserves climatic events from the Little Ice Age and the Medieval Warm
Period. The authors noted, "The late Holocene records clearly identify
Neoglacial events of the Little Ice Age (LIA) and Medieval Warm Period
(MWP)." Some Antarctic regions were atypically cold, whereas others were atypically warm between 1000 and 1200.
Pacific Ocean
Corals in the tropical Pacific Ocean suggest that relatively cool, dry conditions may have persisted early in the millennium, consistent with a La Niña-like configuration of the El Niño-Southern Oscillation patterns.
In 2013 a study from three US universities publicized in Science
magazine showed that the water temperature in the Pacific Ocean was 0.9
degrees warmer during Medieval Warmth Period than during the little ice
age and 0.65 degrees warmer than the decades before the study.
South America
The Medieval Warm Period has been noted in Chile in a 1500-year lake bed sediment core as well as in the Eastern Cordillera of Ecuador.
A reconstruction based on ice cores found the Medieval Warm
Period could be distinguished in tropical South America from about 1050
to 1300 that was followed, in the 15th century, by the Little Ice Age.
Peak temperatures did not rise as high as those from the late 20th
century, which were unprecedented in the area during the study period of
1600 years.
Asia
Adhikari and Kumon (2001), investigating sediments in Lake Nakatsuna in central Japan,
found a warm period from 900 to 1200 that corresponded to the Medieval
Warm Period and three cool phases, two of which could be related to the
Little Ice Age.
Another research in northeastern Japan shows that there is one warm and
humid interval, from 750 to 1200, and two cold and dry intervals, from 1
to 750 and from 1200 to now. Ge et al. studied temperatures in China
during the past 2000 years and found high uncertainty prior to the 16th
century but good consistency over the last 500 years highlighted by the
two cold periods, 1620s–1710s and 1800s–1860s, and the warming during
the 20th century. They also found that the warming during the 10–14th
centuries in some regions might be comparable in magnitude to the
warming of the last few decades of the 20th century, which was
unprecedented within the past 500 years.
Oceania
There is an extreme scarcity of data from Australia
for both the periods of the Medieval Warm Period and the Little Ice
Age. However, evidence from wave-built shingle terraces for a
permanently-full Lake Eyre during the 9th and 10th centuries is consistent with a La Niña-like
configuration, but the data is insufficient to show how lake levels
varied from year to year or what climatic conditions elsewhere in
Australia were like.
A 1979 study from the University of Waikato found,"Temperatures derived from an 18O/16O profile through a stalagmite found in a New Zealand cave (40.67°S, 172.43°E) suggested the Medieval Warm Period to have occurred between AD c. 1050 and c. 1400 and to have been 0.75 °C warmer than the Current Warm Period." More evidence in New Zealand is from an 1100-year tree-ring record.
Popular revolts in late medieval Europe were uprisings and rebellions by (typically) peasants in the countryside, or the bourgeois in towns, against nobles, abbots and kings during the upheavals of the 14th through early 16th centuries, part of a larger "Crisis of the Late Middle Ages". Although sometimes known as Peasant Revolts, the phenomenon of popular uprisings was of broad scope and not just restricted to peasants. In Central Europe and the Balkan region, these rebellions expressed, and helped cause, a political and social disunity paving the way for the expansion of the Ottoman Empire.
Background
Before the 14th century, popular uprisings (such as uprisings at a manor house
against an unpleasant overlord), though not unknown, tended to operate
on a local scale. This changed in the 14th and 15th centuries when new
downward pressures on the poor resulted in mass movements of popular
uprisings across Europe. For example, Germany between 1336 and 1525 witnessed no fewer than sixty instances of militant peasant unrest.
Most of the revolts expressed the desire of those below to share
in the wealth, status, and well-being of those more fortunate. In the
end, they were almost always defeated by the nobles. A new attitude
emerged in Europe, that "peasant" was a pejorative concept, it was
something separate, and seen in a negative light, from those who had
wealth and status.
This was an entirely new social stratification from earlier times when
society had been based on the three orders, those who work, those who
pray, and those who fight, when being a peasant meant being next to God, just like the other orders.
The main reasons cited for these mass uprisings are: an increasing
gap between the wealthy and poor, declining incomes of the poor, rising
inflation and taxation, the external crises of famine, plague and war,
and religious backlashes.
The social gap between rich and poor had become more extreme, the origins of this change can be traced to the 12th century and the rise of the concept of nobility. Dress, behaviour, courtesy, speech, diet, education
— all became part of the noble class, making them distinct from others.
By the 14th century the nobles had indeed become very different in
their behaviour, appearance and values from those "beneath".
The nobles however also faced a crisis of declining income. By 1285 inflation had become rampant (in part due to population pressures) and some nobles charged rent based on customary fixed rates, based on the feudal
system, so as the price of goods and services rose from inflation, the
income of those nobles remained stagnant, effectively dropping. To make matters worse, the nobles had become accustomed to a more luxurious lifestyle that required more money. To address this, nobles illegally raised rents, cheated, stole, and sometimes resorted to outright violence to maintain this lifestyle.
Kings who needed money to finance wars resorted to devaluing
currency by cutting silver and gold coins with less precious metal,
which resulted in increased inflation and, in the end, increased tax
rates.
The 14th century crisis of famine, plague, and war put additional pressures on those at the bottom. The plague drastically reduced the numbers of people who were workers and producing the wealth.
Finally, layered on top of this was a popular ideological view of
the time that property, wealth and inequality were against the
teachings of God, as expressed through the teachings of the Franciscans. The sentiment of the time was probably best expressed by preacher John Ball during the English Peasant Revolt
when he said, "When Adam delved and Eve span, who was then the
gentleman?", criticizing economic inequality as human-made rather than a
creation of God.
Notable rural revolts
The rebellion of György Dózsa in 1514 spread like lightning in the Kingdom of Hungary where hundreds of manor-houses and castles
were burnt and thousands of the gentry killed by impalement,
crucifixion and other methods. Dózsa is here depicted punished with
heated iron chair and crown
The Peasant revolt in Flanders 1323–1328.
Beginning as a series of scattered rural riots in late 1323, peasant
insurrection escalated into a full-scale rebellion that dominated public
affairs in Flanders for nearly five years.
The Jacquerie was a peasant revolt that took place in northern France in 1356-1358, during the Hundred Years' War.
The English Peasants' Revolt
of 1381 or Great Rising of 1381 is a major event in the history of
England. It is the best documented and best known of all the revolts of
this period.
Different historians will use different terms to describe these events. The word peasant,
since the 14th century, has had a pejorative meaning. However, it was
not always that way; peasants were once viewed as pious and seen with
respect and pride. As nobles increasingly lived better quality lives,
there arose a new consciousness of those on top and those below, and the
sense that being a peasant was not a position of equality. This new
consciousness coincided with the popular uprisings of the 14th century.
Research by Rodney Hilton in the 1970s showed that the English Peasant Revolt of 1381
(or Great Rising) was led not by peasants, but by those who would be
the most affected by increased taxation: the merchants who were neither
wealthy, but not poor either. Indeed, these revolts were often
accompanied by landless knights, excommunicated clerics and other
members of society who might find gain or have reason to rebel. Although
these were popular revolts, they were often organized and led by people
who would not have considered themselves peasants.
Peasants is typically a term used for rural agrarian poor
while many uprisings occurred within towns and cities by tradesmen, thus
the term is not fully encompassing of events as a whole for the period.
For historical writing purposes, many modern historians will use the word peasant
with care and respect, choosing other phrases such as "Popular" or
"from below" or "grassroots", although in some countries in central and
eastern Europe where serfdom continued up to the 19th century in places,
the word peasant is still used by some historians as the main description of these events.
In prehistoric times, knowledge and technique were passed from generation to generation in an oral tradition. For instance, the domestication of maize for agriculture has been dated to about 9,000 years ago in southern Mexico, before the development of writing systems.Similarly, archaeological evidence indicates the development of astronomical knowledge in preliterate societies.
The oral tradition of preliterate societies had several features, the first of which was its fluidity.
New information was constantly absorbed and adjusted to new
circumstances or community needs. There were no archives or reports.
This fluidity was closely related to the practical need to explain and
justify a present state of affairs. Another feature was the tendency to describe the universe as just sky and earth, with a potential underworld.
They were also prone to identify causes with beginnings, thereby
providing a historical origin with an explanation. There was also a
reliance on a "medicine man" or "wise woman" for healing, knowledge of divine or demonic causes of diseases, and in more extreme cases, for rituals such as exorcism, divination, songs, and incantations.
Finally, there was an inclination to unquestioningly accept
explanations that might be deemed implausible in more modern times while
at the same time not being aware that such credulous behaviors could
have posed problems.
The development of writing enabled humans to store and
communicate knowledge across generations with much greater accuracy. Its
invention was a prerequisite for the development of philosophy and
later science in ancient times.
Moreover, the extent to which philosophy and science would flourish in
ancient times depended on the efficiency of a writing system (e.g., use
of alphabets).
Earliest roots
The earliest roots of science can be traced to Ancient Egypt and Mesopotamia in around 3000 to 1200 BCE.
Ancient Egypt
Number system and geometry
Starting
in around 3000 BCE, the ancient Egyptians developed a numbering system
that was decimal in character and had orientated their knowledge of
geometry to solving practical problems such as those of surveyors and
builders. They even developed an official calendar that contained twelve months, thirty days each, and five days at the end of the year. Their development of geometry was a necessary outgrowth of surveying to preserve the layout and ownership of farmland, which was flooded annually by the Nile river. The 3-4-5 right triangle and other rules of geometry were used to build rectilinear structures, and the post and lintel architecture of Egypt.
Egypt was also a center of alchemy research for much of the Mediterranean. Based on the medical papyri
written in the 2500–1200 BCE, the ancient Egyptians believed that
disease was mainly caused by the invasion of bodies by evil forces or
spirits. Thus, in addition to using medicines, their healing therapies included prayer, incantation, and ritual. The Ebers Papyrus,
written in around 1600 BCE, contains medical recipes for treating
diseases related to the eyes, mouths, skins, internal organs, and
extremities as well as abscesses, wounds, burns, ulcers, swollen glands,
tumors, headaches, and even bad breath. The Edwin Smith papyrus,
written at about the same time, contains a surgical manual for treating
wounds, fractures, and dislocations. The Egyptians believed that the
effectiveness of their medicines depended on the preparation and
administration under appropriate rituals. Medical historians believe that ancient Egyptian pharmacology, for example, was largely ineffective.
Both the Ebers and Edwin Smith papyri applied the following components
to the treatment of disease: examination, diagnosis, treatment, and
prognosis, which display strong parallels to the basic empirical method of science and, according to G.E.R. Lloyd, played a significant role in the development of this methodology.
Calendar
The
ancient Egyptians even developed an official calendar that contained
twelve months, thirty days each, and five days at the end of the year.
Unlike the Babylonian calendar or the ones used in Greek city-states at
the time, the official Egyptian calendar was much simpler as it was
fixed and did not take lunar and solar cycles into consideration.
Mesopotamia
Clay models of animal livers dating between the nineteenth and eighteenth centuries BCE, found in the royal palace at Mari in what is now Syria
The ancient Mesopotamians had extensive knowledge about the chemical properties of clay, sand, metal ore, bitumen, stone, and other natural materials, and applied this knowledge to practical use in manufacturing pottery, faience, glass, soap, metals, lime plaster, and waterproofing. Metallurgy
required knowledge about the properties of metals. Nonetheless, the
Mesopotamians seem to have had little interest in gathering information
about the natural world for the mere sake of gathering information and
were far more interested in studying the manner in which the gods had
ordered the universe. Biology of non-human organisms was generally only written about in the context of mainstream academic disciplines. Animal physiology was studied extensively for the purpose of divination; the anatomy of the liver, which was seen as an important organ in haruspicy, was studied in particularly intensive detail. Animal behavior
was also studied for divinatory purposes. Most information about the
training and domestication of animals was probably transmitted orally
without being written down, but one text dealing with the training of
horses has survived.
Mesopotamian medicine
The ancient Mesopotamians had no distinction between "rational science" and magic. When a person became ill, doctors prescribed magical formulas to be recited as well as medicinal treatments. The earliest medical prescriptions appear in Sumerian during the Third Dynasty of Ur (c. 2112 BC – c. 2004 BC). The most extensive Babylonian medical text, however, is the Diagnostic Handbook written by the ummânū, or chief scholar, Esagil-kin-apli of Borsippa, during the reign of the Babylonian king Adad-apla-iddina (1069–1046 BC). In East Semitic cultures, the main medicinal authority was a kind of exorcist-healer known as an āšipu. The profession was generally passed down from father to son and was held in extremely high regard. Of less frequent recourse was another kind of healer known as an asu, who corresponds more closely to a modern physician and treated physical symptoms using primarily folk remedies composed of various herbs, animal products, and minerals, as well as potions, enemas, and ointments or poultices.
These physicians, who could be either male or female, also dressed
wounds, set limbs, and performed simple surgeries. The ancient
Mesopotamians also practiced prophylaxis and took measures to prevent the spread of disease.
Mathematics
The Mesopotamian cuneiform tablet Plimpton 322, dating to the eighteenth century BCE, records a number of Pythagorean triplets (3,4,5) (5,12,13) ..., hinting that the ancient Mesopotamians might have been aware of the Pythagorean theorem over a millennium before Pythagoras.
In Babylonian astronomy, records of the motions of the stars, planets, and the moon are left on thousands of clay tablets created by scribes. Even today, astronomical periods identified by Mesopotamian proto-scientists are still widely used in Western calendars such as the solar year and the lunar month.
Using these data they developed arithmetical methods to compute the
changing length of daylight in the course of the year and to predict the
appearances and disappearances of the Moon and planets and eclipses of
the Sun and Moon. Only a few astronomers' names are known, such as that
of Kidinnu, a Chaldean
astronomer and mathematician. Kiddinu's value for the solar year is in
use for today's calendars. Babylonian astronomy was "the first and
highly successful attempt at giving a refined mathematical description
of astronomical phenomena." According to the historian A. Aaboe, "all
subsequent varieties of scientific astronomy, in the Hellenistic world,
in India, in Islam, and in the West—if not indeed all subsequent
endeavour in the exact sciences—depend upon Babylonian astronomy in
decisive and fundamental ways."
To the Babylonians and other Near Eastern
cultures, messages from the gods or omens were concealed in all natural
phenomena that could be deciphered and interpreted by those who are
adept.
Hence, it was believed that the gods could speak through all
terrestrial objects (e.g., animal entrails, dreams, malformed births, or
even the color of a dog urinating on a person) and celestial phenomena. Moreover, Babylonian astrology was inseparable from Babylonian astronomy.
Separate developments
Mathematical
achievements from Mesopotamia had some influence on the development of
mathematics in India, and there were confirmed transmissions of
mathematical ideas between India and China, which were bidirectional. Nevertheless, the mathematical and scientific achievements in India and particularly in China occurred largely independently
from those of Europe and the confirmed early influences that these two
civilizations had on the development of science in Europe in the
pre-modern era were indirect, with Mesopotamia and later the Islamic
World acting as intermediaries. The arrival of modern science, which grew out of the scientific revolution,
in India and China and the greater Asian region in general can be
traced to the scientific activities of Jesuit missionaries who were
interested in studying the region's flora and fauna during the 16th to 17th century.
The earliest traces of mathematical knowledge in the Indian subcontinent appear with the Indus Valley Civilization
(c. 4th millennium BCE ~ c. 3rd millennium BCE). The people of this
civilization made bricks whose dimensions were in the proportion 4:2:1,
considered favorable for the stability of a brick structure. They also tried to standardize measurement of length to a high degree of accuracy. They designed a ruler—the Mohenjo-daro ruler—whose
unit of length (approximately 1.32 inches or 3.4 centimetres) was
divided into ten equal parts. Bricks manufactured in ancient
Mohenjo-daro often had dimensions that were integral multiples of this
unit of length.
In the Tantrasangraha treatise, Nilakantha Somayaji's
updated the Aryabhatan model for the interior planets, Mercury, and
Venus and the equation that he specified for the center of these planets
was more accurate than the ones in European or Islamic astronomy until
the time of Johannes Kepler in the 17th century.
The first textual mention of astronomical concepts comes from the Vedas, religious literature of India. According to Sarma (2008): "One finds in the Rigveda intelligent speculations about the genesis of the universe from nonexistence, the configuration of the universe, the spherical self-supporting earth, and the year of 360 days divided into 12 equal parts of 30 days each with a periodical intercalary month.". The first 12 chapters of the Siddhanta Shiromani, written by Bhāskara
in the 12th century, cover topics such as: mean longitudes of the
planets; true longitudes of the planets; the three problems of diurnal
rotation; syzygies; lunar eclipses; solar eclipses; latitudes of the
planets; risings and settings; the moon's crescent; conjunctions of the
planets with each other; conjunctions of the planets with the fixed
stars; and the patas of the sun and moon. The 13 chapters of the second
part cover the nature of the sphere, as well as significant astronomical
and trigonometric calculations based on it.
Grammar
Some of the earliest linguistic activities can be found in Iron Age India (1st millennium BCE) with the analysis of Sanskrit for the purpose of the correct recitation and interpretation of Vedic texts. The most notable grammarian of Sanskrit was Pāṇini
(c. 520–460 BCE), whose grammar formulates close to 4,000 rules for
Sanskrit. Inherent in his analytic approach are the concepts of the phoneme, the morpheme and the root. The Tolkāppiyam text, composed in the early centuries of the common era,
is a comprehensive text on Tamil grammar, which includes sutras on
orthography, phonology, etymology, morphology, semantics, prosody,
sentence structure and the significance of context in language.
Medicine
Findings from Neolithic graveyards in what is now Pakistan show evidence of proto-dentistry among an early farming culture. The ancient text Suśrutasamhitā of Suśruta describes procedures on various forms of surgery, including rhinoplasty, the repair of torn ear lobes, perineal lithotomy, cataract surgery, and several other excisions and other surgical procedures.
Politics and state
An ancient Indian treatise on statecraft, economic policy and military strategy by Kautilya and Viṣhṇugupta, who are traditionally identified with Chāṇakya
(c. 350–283 BCE). In this treatise, the behaviors and relationships of
the people, the King, the State, the Government Superintendents,
Courtiers, Enemies, Invaders, and Corporations are analysed and
documented. Roger Boesche describes the Arthaśāstra
as "a book of political realism, a book analysing how the political
world does work and not very often stating how it ought to work, a book
that frequently discloses to a king what calculating and sometimes
brutal measures he must carry out to preserve the state and the common
good."
China
Lui Hui's Survey of sea island
Chinese mathematics
From
the earliest the Chinese used a positional decimal system on counting
boards in order to calculate. To express 10, a single rod is placed in
the second box from the right. The spoken language uses a similar system
to English: e.g. four thousand two hundred seven. No symbol was used
for zero. By the 1st century BCE, negative numbers and decimal fractions
were in use and The Nine Chapters on the Mathematical Art included methods for extracting higher order roots by Horner's method and solving linear equations and by Pythagoras' theorem. Cubic equations were solved in the Tang dynasty and solutions of equations of order higher than 3 appeared in print in 1245 CE by Ch'in Chiu-shao. Pascal's triangle for binomial coefficients was described around 1100 by Jia Xian.
Although the first attempts at an axiomatisation of geometry appear in the Mohist canon in 330 BCE, Liu Hui developed algebraic methods in geometry in the 3rd century CE and also calculated pi to 5 significant figures. In 480, Zu Chongzhi improved this by discovering the ratio which remained the most accurate value for 1200 years.
One of the star maps from Su Song's Xin Yi Xiang Fa Yao published in 1092, featuring a cylindrical projection similar to Mercator, and the corrected position of the pole star thanks to Shen Kuo's astronomical observations.
Astronomical observations
Astronomical
observations from China constitute the longest continuous sequence from
any civilization and include records of sunspots (112 records from 364
BCE), supernovas (1054), lunar and solar eclipses. By the 12th century,
they could reasonably accurately make predictions of eclipses, but the
knowledge of this was lost during the Ming dynasty, so that the Jesuit Matteo Ricci gained much favour in 1601 by his predictions.
By 635 Chinese astronomers had observed that the tails of comets always point away from the sun.
From antiquity, the Chinese used an equatorial system for
describing the skies and a star map from 940 was drawn using a
cylindrical (Mercator) projection. The use of an armillary sphere is recorded from the 4th century BCE and a sphere permanently mounted in equatorial axis from 52 BCE. In 125 CE Zhang Heng
used water power to rotate the sphere in real time. This included rings
for the meridian and ecliptic. By 1270 they had incorporated the
principles of the Arab torquetum.
A modern replica of Han dynasty polymath scientist Zhang Heng's seismometer of 132 CE
Inventions
To better prepare for calamities, Zhang Heng invented a seismometer
in 132 CE which provided instant alert to authorities in the capital
Luoyang that an earthquake had occurred in a location indicated by a
specific cardinal or ordinal direction.
Although no tremors could be felt in the capital when Zhang told the
court that an earthquake had just occurred in the northwest, a message
came soon afterwards that an earthquake had indeed struck 400 km
(248 mi) to 500 km (310 mi) northwest of Luoyang (in what is now modern Gansu).
Zhang called his device the 'instrument for measuring the seasonal
winds and the movements of the Earth' (Houfeng didong yi 候风地动仪),
so-named because he and others thought that earthquakes were most likely
caused by the enormous compression of trapped air.
There are many notable contributors to early Chinese disciplines,
inventions, and practices throughout the ages. One of the best examples
would be the medieval Song Chinese Shen Kuo (1031–1095), a polymath and statesman who was the first to describe the magnetic-needle compass used for navigation, discovered the concept of true north, improved the design of the astronomical gnomon, armillary sphere, sight tube, and clepsydra, and described the use of drydocks to repair boats. After observing the natural process of the inundation of silt and the find of marinefossils in the Taihang Mountains (hundreds of miles from the Pacific Ocean), Shen Kuo devised a theory of land formation, or geomorphology. He also adopted a theory of gradual climate change in regions over time, after observing petrifiedbamboo found underground at Yan'an, Shaanxi province. If not for Shen Kuo's writing, the architectural works of Yu Hao would be little known, along with the inventor of movable typeprinting, Bi Sheng (990–1051). Shen's contemporary Su Song
(1020–1101) was also a brilliant polymath, an astronomer who created a
celestial atlas of star maps, wrote a treatise related to botany, zoology, mineralogy, and metallurgy, and had erected a large astronomicalclocktower in Kaifeng city in 1088. To operate the crowning armillary sphere, his clocktower featured an escapement mechanism and the world's oldest known use of an endless power-transmitting chain drive.
However, cultural factors prevented these Chinese achievements
from developing into "modern science". According to Needham, it may have
been the religious and philosophical framework of Chinese intellectuals
which made them unable to accept the ideas of laws of nature:
It was not that there was no order
in nature for the Chinese, but rather that it was not an order ordained
by a rational personal being, and hence there was no conviction that
rational personal beings would be able to spell out in their lesser
earthly languages the divine code of laws which he had decreed
aforetime. The Taoists,
indeed, would have scorned such an idea as being too naïve for the
subtlety and complexity of the universe as they intuited it.
Classical antiquity
The contributions of the Ancient Egyptians and Mesopotamians in the
areas of astronomy, mathematics, and medicine had entered and shaped
Greek natural philosophy of classical antiquity, whereby formal attempts were made to provide explanations of events in the physical world based on natural causes.
Inquiries were also aimed at such practical goals such as establishing a
reliable calendar or determining how to cure a variety of illnesses.
The ancient people who were considered the first scientists may have thought of themselves as natural philosophers, as practitioners of a skilled profession (for example, physicians), or as followers of a religious tradition (for example, temple healers).
Pre-socratics
The earliest Greek philosophers, known as the pre-Socratics, provided competing answers to the question found in the myths of their neighbors: "How did the ordered cosmos in which we live come to be?" The pre-Socratic philosopher Thales (640–546 BCE) of Miletus, identified by later authors such as Aristotle as the first of the Ionian philosophers,
postulated non-supernatural explanations for natural phenomena. For
example, that land floats on water and that earthquakes are caused by
the agitation of the water upon which the land floats, rather than the
god Poseidon. Thales' student Pythagoras of Samos founded the Pythagorean school, which investigated mathematics for its own sake, and was the first to postulate that the Earth is spherical in shape. Leucippus (5th century BCE) introduced atomism, the theory that all matter is made of indivisible, imperishable units called atoms. This was greatly expanded on by his pupil Democritus and later Epicurus.
Plato and Aristotle
produced the first systematic discussions of natural philosophy, which
did much to shape later investigations of nature. Their development of deductive reasoning was of particular importance and usefulness to later scientific inquiry. Plato founded the Platonic Academy
in 387 BCE, whose motto was "Let none unversed in geometry enter here",
and turned out many notable philosophers. Plato's student Aristotle
introduced empiricism
and the notion that universal truths can be arrived at via observation
and induction, thereby laying the foundations of the scientific method. Aristotle also produced many biological writings
that were empirical in nature, focusing on biological causation and the
diversity of life. He made countless observations of nature, especially
the habits and attributes of plants and animals on Lesbos, classified more than 540 animal species, and dissected at least 50. Aristotle's writings profoundly influenced subsequent Islamic and European scholarship, though they were eventually superseded in the Scientific Revolution.
The important legacy of this period included substantial advances in factual knowledge, especially in anatomy, zoology, botany, mineralogy, geography, mathematics and astronomy;
an awareness of the importance of certain scientific problems,
especially those related to the problem of change and its causes; and a
recognition of the methodological importance of applying mathematics to
natural phenomena and of undertaking empirical research. In the Hellenistic age
scholars frequently employed the principles developed in earlier Greek
thought: the application of mathematics and deliberate empirical
research, in their scientific investigations. Thus, clear unbroken lines of influence lead from ancient Greek and Hellenistic philosophers, to medieval Muslim philosophers and scientists, to the European Renaissance and Enlightenment, to the secular sciences of the modern day.
Neither reason nor inquiry began with the Ancient Greeks, but the Socratic method did, along with the idea of Forms, great advances in geometry, logic, and the natural sciences. According to Benjamin Farrington, former Professor of Classics at Swansea University:
"Men were weighing for thousands of years before Archimedes
worked out the laws of equilibrium; they must have had practical and
intuitional knowledge of the principles involved. What Archimedes did
was to sort out the theoretical implications of this practical knowledge
and present the resulting body of knowledge as a logically coherent
system."
and again:
"With astonishment we find ourselves on the threshold of modern
science. Nor should it be supposed that by some trick of translation the
extracts have been given an air of modernity. Far from it. The
vocabulary of these writings and their style are the source from which
our own vocabulary and style have been derived."
The astronomer Aristarchus of Samos was the first known person to propose a heliocentric model of the solar system, while the geographer Eratosthenes accurately calculated the circumference of the Earth. Hipparchus (c. 190 – c. 120 BCE) produced the first systematic star catalog. The level of achievement in Hellenistic astronomy and engineering is impressively shown by the Antikythera mechanism (150–100 BCE), an analog computer
for calculating the position of planets. Technological artifacts of
similar complexity did not reappear until the 14th century, when
mechanical astronomical clocks appeared in Europe.
Hellenistic medicine
In medicine, Hippocrates (c. 460 BC – c. 370 BCE) and his followers were the first to describe many diseases and medical conditions and developed the Hippocratic Oath for physicians, still relevant and in use today. Herophilos (335–280 BCE) was the first to base his conclusions on dissection of the human body and to describe the nervous system. Galen (129 – c. 200 CE) performed many audacious operations—including brain and eye surgeries— that were not tried again for almost two millennia.
One of the oldest surviving fragments of Euclid's Elements, found at Oxyrhynchus and dated to c. 100 CE.
In Hellenistic Egypt, the mathematician Euclid laid down the foundations of mathematical rigor and introduced the concepts of definition, axiom, theorem and proof still in use today in his Elements, considered the most influential textbook ever written. Archimedes, considered one of the greatest mathematicians of all time, is credited with using the method of exhaustion to calculate the area under the arc of a parabola with the summation of an infinite series, and gave a remarkably accurate approximation of pi. He is also known in physics for laying the foundations of hydrostatics, statics, and the explanation of the principle of the lever.
Other developments
Theophrastus wrote some of the earliest descriptions of plants and animals, establishing the first taxonomy and looking at minerals in terms of their properties such as hardness. Pliny the Elder produced what is one of the largest encyclopedias
of the natural world in 77 CE, and must be regarded as the rightful
successor to Theophrastus. For example, he accurately describes the octahedral shape of the diamond, and proceeds to mention that diamond dust is used by engravers to cut and polish other gems owing to its great hardness. His recognition of the importance of crystal shape is a precursor to modern crystallography,
while mention of numerous other minerals presages mineralogy. He also
recognises that other minerals have characteristic crystal shapes, but
in one example, confuses the crystal habit with the work of lapidaries. He was also the first to recognise that amber was a fossilized resin from pine trees because he had seen samples with trapped insects within them.
The development of the field of archaeology has it roots with
history and with those who were interested in the past, such as kings
and queens who wanted to show past glories of their respective nations.
The 5th-century-BCE Greek historianHerodotus was the first scholar to systematically study the past and perhaps the first to examine artifacts.
Greek scholarship under Roman rule
During the rule of Rome, famous historians such as Polybius, Livy and Plutarch documented the rise of the Roman Republic, and the organization and histories of other nations, while statesmen like Julius Caesar,
Cicero, and others provided examples of the politics of the republic
and Rome's empire and wars. The study of politics during this age was
oriented toward understanding history, understanding methods of
governing, and describing the operation of governments.
The Roman conquest of Greece did not diminish learning and culture in the Greek provinces. On the contrary, the appreciation of Greek achievements in literature, philosophy, politics, and the arts by Rome's upper class coincided with the increased prosperity of the Roman Empire.
Greek settlements had existed in Italy for centuries and the ability to
read and speak Greek was not uncommon in Italian cities such as Rome.
Moreover, the settlement of Greek scholars in Rome, whether voluntarily
or as slaves, gave Romans access to teachers of Greek literature and
philosophy. Conversely, young Roman scholars also studied abroad in
Greece and upon their return to Rome, were able to convey Greek
achievements to their Latin leadership.
And despite the translation of a few Greek texts into Latin, Roman
scholars who aspired to the highest level did so using the Greek
language. The Roman statesman and philosopher Cicero (106 – 43 BCE) was a prime example. He had studied under Greek teachers in Rome and then in Athens and Rhodes.
He mastered considerable portions of Greek philosophy, wrote Latin
treatises on several topics, and even wrote Greek commentaries of
Plato's Timaeus as well as a Latin translation of it, which has not survived.
In the beginning, support for scholarship in Greek knowledge was almost entirely funded by the Roman upper class.
There were all sorts of arrangements, ranging from a talented scholar
being attached to a wealthy household to owning educated Greek-speaking
slaves.
In exchange, scholars who succeeded at the highest level had an
obligation to provide advice or intellectual companionship to their
Roman benefactors, or to even take care of their libraries. The less
fortunate or accomplished ones would teach their children or perform
menial tasks.
The level of detail and sophistication of Greek knowledge was adjusted
to suit the interests of their Roman patrons. That meant popularizing
Greek knowledge by presenting information that were of practical value
such as medicine or logic (for courts and politics) but excluding subtle
details of Greek metaphysics and epistemology. Beyond the basics, the
Romans did not value natural philosophy and considered it an amusement
for leisure time.
Commentaries and encyclopedias were the means by which Greek knowledge was popularized for Roman audiences. The Greek scholar Posidonius
(c. 135-c. 51 BCE), a native of Syria, wrote prolifically on history,
geography, moral philosophy, and natural philosophy. He greatly
influenced Latin writers such as Marcus Terentius Varro (116-27 BCE), who wrote the encyclopedia Nine Books of Disciplines,
which covered nine arts: grammar, rhetoric, logic, arithmetic,
geometry, astronomy, musical theory, medicine, and architecture. The Disciplines
became a model for subsequent Roman encyclopedias and Varro's nine
liberal arts were considered suitable education for a Roman gentleman.
The first seven of Varro's nine arts would later define the seven liberal arts of medieval schools. The pinnacle of the popularization movement was the Roman scholar Pliny the Elder
(23/24–79 CE), a native of northern Italy, who wrote several books on
the history of Rome and grammar. His most famous work was his voluminous
Natural History.
After the death of the Roman Emperor Marcus Aurelius
in 180 CE, the favorable conditions for scholarship and learning in the
Roman Empire were upended by political unrest, civil war, urban decay,
and looming economic crisis. In around 250 CE, barbarians
began attacking and invading the Roman frontiers. These combined events
led to a general decline in political and economic conditions. The
living standards of the Roman upper class was severely impacted, and
their loss of leisure diminished scholarly pursuits. Moreover, during the 3rd and 4th centuries CE, the Roman Empire was administratively divided into two halves: Greek East and Latin West. These administrative divisions weakened the intellectual contact between the two regions. Eventually, both halves went their separate ways, with the Greek East becoming the Byzantine Empire. Christianity
was also steadily expanding during this time and soon became a major
patron of education in the Latin West. Initially, the Christian church
adopted some of the reasoning tools of Greek philosophy in the 2nd and
3rd centuries CE to defend its faith against sophisticated opponents. Nevertheless, Greek philosophy received a mixed reception from leaders and adherents of the Christian faith. Some such as Tertullian (c. 155-c. 230 CE) were vehemently opposed to philosophy, denouncing it as heretic. Others such as Augustine of Hippo
(354-430 CE) were ambivalent and defended Greek philosophy and science
as the best ways to understand the natural world and therefore treated
it as a handmaiden (or servant) of religion. Education in the West began its gradual decline, along with the rest of Western Roman Empire,
due to invasions by Germanic tribes, civil unrest, and economic
collapse. Contact with the classical tradition was lost in specific
regions such as Roman Britain and northern Gaul but continued to exist in Rome, northern Italy, southern Gaul, Spain, and North Africa.
Middle Ages
In
the Middle Ages, the classical learning continued in three major
linguistic cultures and civilizations: Greek (the Byzantine Empire),
Arabic (the Islamic world), and Latin (Western Europe).
Byzantine Empire
The frontispiece of the Vienna Dioscurides, which shows a set of seven famous physicians
While the Byzantine Empire still held learning centers such as Constantinople, Alexandria and Antioch, Western Europe's knowledge was concentrated in monasteries until the development of medieval universities
in the 12th centuries. The curriculum of monastic schools included the
study of the few available ancient texts and of new works on practical
subjects like medicine and timekeeping.
In the sixth century in the Byzantine Empire, Isidore of Miletus compiled Archimedes' mathematical works in the Archimedes Palimpsest, where all Archimedes' mathematical contributions were collected and studied.
John Philoponus, another Byzantine scholar, was the first to question Aristotle's teaching of physics, introducing the theory of impetus.
The theory of impetus was an auxiliary or secondary theory of
Aristotelian dynamics, put forth initially to explain projectile motion
against gravity. It is the intellectual precursor to the concepts of
inertia, momentum and acceleration in classical mechanics. The works of John Philoponus inspired Galileo Galilei ten centuries later.
The first record of separating conjoined twins took place in the Byzantine Empire
in the 900s when the surgeons tried to separate a dead body of a pair
of conjoined twins. The result was partly successful as the other twin
managed to live for three days. The next recorded case of separating
conjoined twins was several centuries later, in 1600s Germany.
Collapse
During the Fall of Constantinople in 1453, a number of Greek scholars fled to North Italy in which they fueled the era later commonly known as the "Renaissance"
as they brought with them a great deal of classical learning including
an understanding of botany, medicine, and zoology. Byzantium also gave
the West important inputs: John Philoponus' criticism of Aristotelian
physics, and the works of Dioscorides.
This was the period (8th–14th century CE) of the Islamic Golden Age where commerce thrived, and new ideas and technologies emerged such as the importation of papermaking from China, which made the copying of manuscripts inexpensive.
Translations and Hellenization
The
eastward transmission of Greek heritage to Western Asia was a slow and
gradual process that spanned over a thousand years, beginning with the
Asian conquests of Alexander the Great in 335 BCE to the founding of Islam in the 7th century CE. The birth and expansion of Islam during the 7th century was quickly followed by its Hellenization. Knowledge of Greek conceptions of the world
was preserved and absorbed into Islamic theology, law, culture, and
commerce, which was aided by the translations of traditional Greek texts
and some Syriac intermediary sources into Arabic during the 8th–9th century.
Education and scholarly pursuits
Higher education at a madrasa (or college) was focused on Islamic law and religious science and students had to engage in self-study for everything else.
And despite the occasional theological backlash, many Islamic scholars
of science were able to conduct their work in relatively tolerant urban
centers (e.g., Baghdad and Cairo) and were protected by powerful patrons. They could also travel freely and exchange ideas as there were no political barriers within the unified Islamic state.
Islamic science during this time was primarily focused on the
correction, extension, articulation, and application of Greek ideas to
new problems.
Advancements in mathematics
Most of the achievements by Islamic scholars during this period were in mathematics. Arabic mathematics was a direct descendant of Greek and Indian mathematics. For instance, what is now known as Arabic numerals
originally came from India, but Muslim mathematicians made several key
refinements to the number system, such as the introduction of decimal point notation. Mathematicians such as Muhammad ibn Musa al-Khwarizmi (c. 780–850) gave his name to the concept of the algorithm, while the term algebra is derived from al-jabr, the beginning of the title of one of his publications. Islamic trigonometry continued from the works of Ptolemy's Almagest and Indian Siddhanta, from which they added trigonometric functions,
drew up tables, and applied trignometry to spheres and planes. Many of
their engineers, instruments makers, and surveyors contributed books in
applied mathematics. It was in astronomy that Islamic mathematicians made their greatest contributions. Al-Battani (c. 858–929) improved the measurements of Hipparchus, preserved in the translation of Ptolemy's Hè Megalè Syntaxis (The great treatise) translated as Almagest. Al-Battani also improved the precision of the measurement of the precession of the Earth's axis. Corrections were made to Ptolemy's geocentric model by al-Battani, Ibn al-Haytham, Averroes and the Maragha astronomers such as Nasir al-Din al-Tusi, Mo'ayyeduddin Urdi and Ibn al-Shatir.
Scholars with geometric skills made significant improvements to
the earlier classical texts on light and sight by Euclid, Aristotle, and
Ptolemy. The earliest surviving Arabic treatises were written in the 9th century by Abū Ishāq al-Kindī, Qustā ibn Lūqā, and (in fragmentary form) Ahmad ibn Isā. Later in the 11th century, Ibn al-Haytham
(known as Alhazen in the West), a mathematician and astronomer,
synthesized a new theory of vision based on the works of his
predecessors. His new theory included a complete system of geometrical optics, which was set in great detail in his Book of Optics.
His book was translated into Latin and was relied upon as a principal
source on the science of optics in Europe until the 17th century.
Institutionalization of medicine
The medical sciences were prominently cultivated in the Islamic world.
The works of Greek medical theories, especially those of Galen, were
translated into Arabic and there was an outpouring of medical texts by
Islamic physicians, which were aimed at organizing, elaborating, and
disseminating classical medical knowledge. Medical specialties started to emerge, such as those involved in the treatment of eye diseases such as cataracts. Ibn Sina (known as Avicenna in the West, c. 980–1037) was a prolific Persian medical encyclopedist wrote extensively on medicine, with his two most notable works in medicine being the Kitāb al-shifāʾ ("Book of Healing") and The Canon of Medicine,
both of which were used as standard medicinal texts in both the Muslim
world and in Europe well into the 17th century. Amongst his many
contributions are the discovery of the contagious nature of infectious
diseases, and the introduction of clinical pharmacology.
Institutionalization of medicine was another important achievement in
the Islamic world. Although hospitals as an institution for the sick
emerged in the Byzantium empire, the model of institutionalized medicine
for all social classes was extensive in the Islamic empire and was
scattered throughout. In addition to treating patients, physicians could
teach apprentice physicians, as well write and do research. The
discovery of the pulmonary transit of blood in the human body by Ibn al-Nafis occurred in a hospital setting.
Decline
Islamic science began its decline in the 12th–13th century, before the Renaissance in Europe, due in part to the Christian reconquest of Spain and the Mongol conquests in the East in the 11th–13th century. The Mongols sacked Baghdad, capital of the Abbasid caliphate, in 1258, which ended the Abbasid empire. Nevertheless, many of the conquerors became patrons of the sciences. Hulagu Khan, for example, who led the siege of Baghdad, became a patron of the Maragheh observatory. Islamic astronomy continued to flourish into the 16th century.
By the eleventh century, most of Europe had become Christian;
stronger monarchies emerged; borders were restored; technological
developments and agricultural innovations were made, increasing the food
supply and population. Classical Greek texts were translated from
Arabic and Greek into Latin, stimulating scientific discussion in
Western Europe.
In classical antiquity,
Greek and Roman taboos had meant that dissection was usually banned,
but in the Middle Ages medical teachers and students at Bologna began to
open human bodies, and Mondino de Luzzi (c. 1275–1326) produced the first known anatomy textbook based on human dissection.
As a result of the Pax Mongolica, Europeans, such as Marco Polo,
began to venture further and further east. The written accounts of Polo
and his fellow travelers inspired other Western European maritime
explorers to search for a direct sea route to Asia, ultimately leading
to the Age of Discovery.
An intellectual revitalization of Western Europe started with the birth of medieval universities in the 12th century. These urban institutions grew from the informal scholarly activities of learned friars who visited monasteries, consulted libraries, and conversed with other fellow scholars. A friar who became well-known would attract a following of disciples, giving rise to a brotherhood of scholars (or collegium in Latin). A collegium might travel to a town or request a monastery to host them. However, if the number of scholars within a collegium grew too large, they would opt to settle in a town instead. As the number of collegia within a town grew, the collegia might request that their king grant them a charter that would convert them into a universitas. Many universities were chartered during this period, with the first in Bologna in 1088, followed by Paris in 1150, Oxford in 1167, and Cambridge in 1231. The granting of a charter meant that the medieval universities were partially sovereign and independent from local authorities.
Their independence allowed them to conduct themselves and judge their
own members based on their own rules. Furthermore, as initially
religious institutions, their faculties and students were protected from
capital punishment (e.g., gallows).
Such independence was a matter of custom, which could, in principle, be
revoked by their respective rulers if they felt threatened. Discussions
of various subjects or claims at these medieval institutions, no matter
how controversial, were done in a formalized way so as to declare such
discussions as being within the bounds of a university and therefore
protected by the privileges of that institution's sovereignty. A claim could be described as ex cathedra (literally "from the chair", used within the context of teaching) or ex hypothesi
(by hypothesis). This meant that the discussions were presented as
purely an intellectual exercise that did not require those involved to
commit themselves to the truth of a claim or to proselytize. Modern
academic concepts and practices such as academic freedom or freedom of inquiry are remnants of these medieval privileges that were tolerated in the past.
The curriculum of these medieval institutions centered on the seven liberal arts, which were aimed at providing beginning students with the skills for reasoning and scholarly language. Students would begin their studies starting with the first three liberal arts or Trivium (grammar, rhetoric, and logic) followed by the next four liberal arts or Quadrivium (arithmetic, geometry, astronomy, and music). Those who completed these requirements and received their baccalaureate (or Bachelor of Arts) had the option to join the higher faculty (law, medicine, or theology), which would confer an LLD for a lawyer, an MD for a physician, or ThD for a theologian.
Students who chose to remain in the lower faculty (arts) could work towards a Magister (or Master's) degree and would study three philosophies: metaphysics, ethics, and natural philosophy. Latin translations of Aristotle's works such as De Anima (On the Soul)
and the commentaries on them were required readings. As time passed,
the lower faculty was allowed to confer its own doctoral degree called
the PhD.
Many of the Masters were drawn to encyclopedias and had used them as
textbooks. But these scholars yearned for the complete original texts of
the Ancient Greek philosophers, mathematicians, and physicians such as Aristotle, Euclid, and Galen,
which were not available to them at the time. These Ancient Greek texts
were to be found in the Byzantine Empire and the Islamic World.
Translations of Greek and Arabic sources
Contact with the Byzantine Empire, and with the Islamic world during the Reconquista and the Crusades, allowed Latin Europe access to scientific Greek and Arabic texts, including the works of Aristotle, Ptolemy, Isidore of Miletus, John Philoponus, Jābir ibn Hayyān, al-Khwarizmi, Alhazen, Avicenna, and Averroes. European scholars had access to the translation programs of Raymond of Toledo, who sponsored the 12th century Toledo School of Translators from Arabic to Latin. Later translators like Michael Scotus would learn Arabic in order to study these texts directly. The European universities aided materially in the translation and propagation of these texts
and started a new infrastructure which was needed for scientific
communities. In fact, European university put many works about the
natural world and the study of nature at the center of its curriculum,
with the result that the "medieval university laid far greater emphasis
on science than does its modern counterpart and descendent."
At the beginning of the 13th century, there were reasonably
accurate Latin translations of the main works of almost all the
intellectually crucial ancient authors, allowing a sound transfer of
scientific ideas via both the universities and the monasteries. By then,
the natural philosophy in these texts began to be extended by scholastics such as Robert Grosseteste, Roger Bacon, Albertus Magnus and Duns Scotus.
Precursors of the modern scientific method, influenced by earlier
contributions of the Islamic world, can be seen already in Grosseteste's
emphasis on mathematics as a way to understand nature, and in the
empirical approach admired by Bacon, particularly in his Opus Majus. Pierre Duhem's thesis is that Stephen Tempier – the Bishop of Paris – Condemnation of 1277
led to the study of medieval science as a serious discipline, "but no
one in the field any longer endorses his view that modern science
started in 1277". However, many scholars agree with Duhem's view that the mid-late Middle Ages saw important scientific developments.
Medieval science
The first half of the 14th century saw much important scientific work, largely within the framework of scholastic commentaries on Aristotle's scientific writings. William of Ockham emphasised the principle of parsimony:
natural philosophers should not postulate unnecessary entities, so that
motion is not a distinct thing but is only the moving object and an intermediary "sensible species" is not needed to transmit an image of an object to the eye. Scholars such as Jean Buridan and Nicole Oresme
started to reinterpret elements of Aristotle's mechanics. In
particular, Buridan developed the theory that impetus was the cause of
the motion of projectiles, which was a first step towards the modern
concept of inertia. The Oxford Calculators began to mathematically analyze the kinematics of motion, making this analysis without considering the causes of motion.
In 1348, the Black Death
and other disasters sealed a sudden end to philosophic and scientific
development. Yet, the rediscovery of ancient texts was stimulated by the
Fall of Constantinople in 1453, when many Byzantine
scholars sought refuge in the West. Meanwhile, the introduction of
printing was to have great effect on European society. The facilitated
dissemination of the printed word democratized learning and allowed
ideas such as algebra to propagate more rapidly. These developments paved the way for the Scientific Revolution, where scientific inquiry, halted at the start of the Black Death, resumed.
Renaissance
Revival of learning
The renewal of learning in Europe began with 12th century Scholasticism. The Northern Renaissance
showed a decisive shift in focus from Aristotelian natural philosophy
to chemistry and the biological sciences (botany, anatomy, and
medicine). Thus modern science in Europe was resumed in a period of great upheaval: the Protestant Reformation and CatholicCounter-Reformation; the discovery of the Americas by Christopher Columbus; the Fall of Constantinople;
but also the re-discovery of Aristotle during the Scholastic period
presaged large social and political changes. Thus, a suitable
environment was created in which it became possible to question
scientific doctrine, in much the same way that Martin Luther and John Calvin questioned religious doctrine. The works of Ptolemy (astronomy) and Galen (medicine) were found not always to match everyday observations. Work by Vesalius on human cadavers found problems with the Galenic view of anatomy.
Theophrastus' work on rocks, Peri lithōn, remained authoritative for millennia: its interpretation of fossils was not overturned until after the Scientific Revolution.
The early modern period
is seen as a flowering of the European Renaissance. There was a
willingness to question previously held truths and search for new
answers resulted in a period of major scientific advancements, now known
as the Scientific Revolution, which led to the emergence of a New Science that was more mechanistic in its worldview, more integrated with mathematics, and more reliable and open as its knowledge was based on a newly defined scientific method.
The scientific revolution is a convenient boundary between ancient
thought and classical physics, and is traditionally held by most
historians to have begun in 1543, when the books De humani corporis fabrica (On the Workings of the Human Body) by Andreas Vesalius, and also De Revolutionibus, by the astronomer Nicolaus Copernicus, were first printed. The period culminated with the publication of the Philosophiæ Naturalis Principia Mathematica in 1687 by Isaac Newton, representative of the unprecedented growth of scientific publications throughout Europe.
The
scientific method was also better developed as the modern way of
thinking emphasized experimentation and reason over traditional
considerations. Galileo ("Father of Modern Physics") also made use of experiments to validate physical theories, a key element of the scientific method.
Age of Enlightenment
Continuation of Scientific Revolution
The Scientific Revolution continued into the Age of Enlightenment, which accelerated the development of modern science.
Planets and orbits
The heliocentric model that was revived by Nicolaus Copernicus was followed by the first known model of planetary motion given by Johannes Kepler in the early 17th century, which proposed that the planets follow elliptical orbits, with the Sun at one focus of the ellipse.
William Harvey published De Motu Cordis
in 1628, which revealed his conclusions based on his extensive studies
of vertebrate circulatory systems. He identified the central role of
the heart, arteries, and veins in producing blood movement in a circuit,
and failed to find any confirmation of Galen's pre-existing notions of
heating and cooling functions. The history of early modern biology and medicine is often told through the search for the seat of the soul.
Galen in his descriptions of his foundational work in medicine presents
the distinctions between arteries, veins, and nerves using the
vocabulary of the soul.
Geology did not undergo systematic restructuring during the Scientific Revolution
but instead existed as a cloud of isolated, disconnected ideas about
rocks, minerals, and landforms long before it became a coherent science.
Robert Hooke formulated a theory of earthquakes, and Nicholas Steno developed the theory of superposition and argued that fossils were the remains of once-living creatures. Beginning with Thomas Burnet's Sacred Theory of the Earth
in 1681, natural philosophers began to explore the idea that the Earth
had changed over time. Burnet and his contemporaries interpreted Earth's
past in terms of events described in the Bible, but their work laid the
intellectual foundations for secular interpretations of Earth history.
Post-Scientific Revolution
Bioelectricity
During the late 18th century, the Italian physician Luigi Galvani
took an interest in the field of "medical electricity", which emerged
in the middle of the 18th century, following the electrical researches
and the discovery of the effects of electricity on the human body.
Galvani's experiments with bioelectricity has a popular legend which
says that Galvani was slowly skinning a frog at a table where he and his
wife had been conducting experiments with static electricity by rubbing
frog skin. Galvani's assistant touched an exposed sciatic nerve
of the frog with a metal scalpel that had picked up a charge. At that
moment, they saw sparks and the dead frog's leg kicked as if in life.
The observation provided the basis for the new understanding that the
impetus behind muscle movement was electrical energy carried by a liquid
(ions), and not air or fluid as in earlier balloonist theories. The Galvanis are credited with the discovery of bioelectricity.
Developments in geology
Modern geology, like modern chemistry, gradually evolved during the 18th and early 19th centuries. Benoît de Maillet and the Comte de Buffon saw the Earth as much older than the 6,000 years envisioned by biblical scholars. Jean-Étienne Guettard and Nicolas Desmarest
hiked central France and recorded their observations on some of the
first geological maps. Aided by chemical experimentation, naturalists
such as Scotland's John Walker, Sweden's Torbern Bergman, and Germany's Abraham Werner
created comprehensive classification systems for rocks and minerals—a
collective achievement that transformed geology into a cutting edge
field by the end of the eighteenth century. These early geologists also
proposed a generalized interpretations of Earth history that led James Hutton, Georges Cuvier and Alexandre Brongniart, following in the steps of Steno,
to argue that layers of rock could be dated by the fossils they
contained: a principle first applied to the geology of the Paris Basin.
The use of index fossils
became a powerful tool for making geological maps, because it allowed
geologists to correlate the rocks in one locality with those of similar
age in other, distant localities.
The basis for classical economics forms Adam Smith's An Inquiry into the Nature and Causes of the Wealth of Nations, published in 1776. Smith criticized mercantilism, advocating a system of free trade with division of labour. He postulated an "invisible hand"
that regulated economic systems made up of actors guided only by
self-interest. The "invisible hand" mentioned in a lost page in the
middle of a chapter in the middle of the "Wealth of Nations", 1776, advances as Smith's central message.
It is played down that this "invisible hand" acts only "frequently" and
that it is "no part of his [the individual's] intentions" because
competition leads to lower prices by imitating "his" invention. That
this "invisible hand" prefers "the support of domestic to foreign
industry" is cleansed—often without indication that part of the citation
is truncated.
The opening passage of the "Wealth" containing Smith's message is never
mentioned as it cannot be integrated into modern theory: "Wealth"
depends on the division of labour which changes with market volume and
on the proportion of productive to Unproductive labor.
Social science
Anthropology
can best be understood as an outgrowth of the Age of Enlightenment. It
was during this period that Europeans attempted systematically to study
human behavior. Traditions of jurisprudence, history, philology and
sociology developed during this time and informed the development of the
social sciences of which anthropology was a part.
19th century
The 19th century saw the birth of science as a profession. William Whewell had coined the term the term scientist in 1833, which soon replaced the older term natural philosopher.
In
astronomy, the planet Neptune was discovered. Advances in astronomy and
in optical systems in the 19th century resulted in the first
observation of an asteroid (1 Ceres) in 1801, and the discovery of Neptune in 1846. In 1925, Cecilia Payne-Gaposchkin determined that stars were composed mostly of hydrogen and helium. She was dissuaded by astronomer Henry Norris Russell
from publishing this finding in her PhD thesis because of the widely
held belief that stars had the same composition as the Earth. However, four years later, in 1929, Henry Norris Russell came to the same conclusion through different reasoning and the discovery was eventually accepted.
Developments in mathematics
In
mathematics, the notion of complex numbers finally matured and led to a
subsequent analytical theory; they also began the use of hypercomplex numbers. Karl Weierstrass and others carried out the arithmetization of analysis for functions of real and complex variables. It also saw rise to new progress in geometry
beyond those classical theories of Euclid, after a period of nearly two
thousand years. The mathematical science of logic likewise had
revolutionary breakthroughs after a similarly long period of stagnation.
But the most important step in science at this time were the ideas
formulated by the creators of electrical science. Their work changed the
face of physics and made possible for new technology to come about such
as electric power, electrical telegraphy, the telephone, and radio.
In chemistry, Dmitri Mendeleev, following the atomic theory of John Dalton, created the first periodic table of elements.
Other highlights include the discoveries unveiling the nature of atomic
structure and matter, simultaneously with chemistry – and of new kinds
of radiation. The theory that all matter is made of atoms, which are the
smallest constituents of matter that cannot be broken down without
losing the basic chemical and physical properties of that matter, was
provided by John Dalton
in 1803, although the question took a hundred years to settle as
proven. Dalton also formulated the law of mass relationships. In 1869, Dmitri Mendeleev composed his periodic table of elements on the basis of Dalton's discoveries. The synthesis of urea by Friedrich Wöhler opened a new research field, organic chemistry,
and by the end of the 19th century, scientists were able to synthesize
hundreds of organic compounds. The later part of the 19th century saw
the exploitation of the Earth's petrochemicals, after the exhaustion of
the oil supply from whaling.
By the 20th century, systematic production of refined materials
provided a ready supply of products which provided not only energy, but
also synthetic materials for clothing, medicine, and everyday disposable
resources. Application of the techniques of organic chemistry to living
organisms resulted in physiological chemistry, the precursor to biochemistry.
Age of the Earth
Over the first half of the 19th century, geologists such as Charles Lyell, Adam Sedgwick, and Roderick Murchison
applied the new technique to rocks throughout Europe and eastern North
America, setting the stage for more detailed, government-funded mapping
projects in later decades. Midway through the 19th century, the focus of
geology shifted from description and classification to attempts to
understand how the surface of the Earth had changed. The first
comprehensive theories of mountain building were proposed during this
period, as were the first modern theories of earthquakes and volcanoes. Louis Agassiz and others established the reality of continent-covering ice ages, and "fluvialists" like Andrew Crombie Ramsay argued that river valleys were formed, over millions of years by the rivers that flow through them. After the discovery of radioactivity, radiometric dating methods were developed, starting in the 20th century. Alfred Wegener's
theory of "continental drift" was widely dismissed when he proposed it
in the 1910s, but new data gathered in the 1950s and 1960s led to the
theory of plate tectonics,
which provided a plausible mechanism for it. Plate tectonics also
provided a unified explanation for a wide range of seemingly unrelated
geological phenomena. Since 1970 it has served as the unifying principle
in geology.
Evolution and inheritance
In mid-July 1837 Darwin started his "B" notebook on Transmutation of Species, and on page 36 wrote "I think" above his first evolutionary tree.
Perhaps the most prominent, controversial, and far-reaching theory in all of science has been the theory of evolution by natural selection, which was independently formulated by Charles Darwin and Alfred Wallace. It was described in detail in Darwin's book The Origin of Species,
which was published in 1859. In it, Darwin proposed that the features
of all living things, including humans, were shaped by natural processes
over long periods of time. The theory of evolution in its current form
affects almost all areas of biology. Implications of evolution on fields outside of pure science have led to both opposition and support
from different parts of society, and profoundly influenced the popular
understanding of "man's place in the universe". Separately, Gregor Mendel formulated in the principles of inheritance in 1866, which became the basis of modern genetics.
Germ theory
Another important landmark in medicine and biology were the successful efforts to prove the germ theory of disease. Following this, Louis Pasteur made the first vaccine against rabies, and also made many discoveries in the field of chemistry, including the asymmetry of crystals. In 1847, Hungarian physician Ignác Fülöp Semmelweis dramatically reduced the occurrency of puerperal fever by simply requiring physicians to wash their hands before attending to women in childbirth. This discovery predated the germ theory of disease.
However, Semmelweis' findings were not appreciated by his
contemporaries and handwashing came into use only with discoveries by
British surgeon Joseph Lister, who in 1865 proved the principles of antisepsis. Lister's work was based on the important findings by French biologist Louis Pasteur.
Pasteur was able to link microorganisms with disease, revolutionizing
medicine. He also devised one of the most important methods in preventive medicine, when in 1880 he produced a vaccine against rabies. Pasteur invented the process of pasteurization, to help prevent the spread of disease through milk and other foods.
Schools of economics
Karl Marx developed an alternative economic theory, called Marxian economics. Marxian economics is based on the labor theory of value and assumes the value of good to be based on the amount of labor required to produce it. Under this axiom, capitalism was based on employers not paying the full value of workers labor to create profit. The Austrian School responded to Marxian economics by viewing entrepreneurship as driving force of economic development. This replaced the labor theory of value by a system of supply and demand.
Founding of psychology
Psychology as a scientific enterprise that was independent from philosophy began in 1879 when Wilhelm Wundt founded the first laboratory dedicated exclusively to psychological research (in Leipzig). Other important early contributors to the field include Hermann Ebbinghaus (a pioneer in memory studies), Ivan Pavlov (who discovered classical conditioning), William James, and Sigmund Freud. Freud's influence has been enormous, though more as cultural icon than a force in scientific psychology.
Modern sociology
Modern
sociology emerged in the early 19th century as the academic response to
the modernization of the world. Among many early sociologists (e.g., Émile Durkheim), the aim of sociology was in structuralism, understanding the cohesion of social groups, and developing an "antidote" to social disintegration. Max Weber was concerned with the modernization of society through the concept of rationalization, which he believed would trap individuals in an "iron cage" of rational thought. Some sociologists, including Georg Simmel and W. E. B. Du Bois, utilized more microsociological, qualitative analyses. This microlevel approach played an important role in American sociology, with the theories of George Herbert Mead and his student Herbert Blumer resulting in the creation of the symbolic interactionism
approach to sociology. In particular, just Auguste Comte, illustrated
with his work the transition from a theological to a metaphysical stage
and, from this, to a positive stage. Comte took care of the
classification of the sciences as well as a transit of humanity towards a
situation of progress attributable to a re-examination of nature
according to the affirmation of 'sociality' as the basis of the
scientifically interpreted society.
Romanticism
The Romantic Movement
of the early 19th century reshaped science by opening up new pursuits
unexpected in the classical approaches of the Enlightenment. The decline
of Romanticism occurred because a new movement, Positivism,
began to take hold of the ideals of the intellectuals after 1840 and
lasted until about 1880. At the same time, the romantic reaction to the
Enlightenment produced thinkers such as Johann Gottfried Herder and later Wilhelm Dilthey whose work formed the basis for the culture concept which is central to the discipline. Traditionally, much of the history of the subject was based on colonial encounters between Western Europe and the rest of the world, and much of 18th- and 19th-century anthropology is now classed as scientific racism.
During the late 19th century, battles over the "study of man" took
place between those of an "anthropological" persuasion (relying on anthropometrical techniques) and those of an "ethnological" persuasion (looking at cultures and traditions), and these distinctions became part of the later divide between physical anthropology and cultural anthropology, the latter ushered in by the students of Franz Boas.
20th century
Science advanced dramatically during the 20th century. There were new and radical developments in the physical and life sciences, building on the progress from the 19th century.
Theory of relativity and quantum mechanics
Einstein's official portrait after receiving the 1921 Nobel Prize in Physics
The beginning of the 20th century brought the start of a revolution
in physics. The long-held theories of Newton were shown not to be
correct in all circumstances. Beginning in 1900, Max Planck, Albert Einstein, Niels Bohr
and others developed quantum theories to explain various anomalous
experimental results, by introducing discrete energy levels. Not only
did quantum mechanics show that the laws of motion did not hold on small scales, but the theory of general relativity, proposed by Einstein in 1915, showed that the fixed background of spacetime, on which both Newtonian mechanics and special relativity depended, could not exist. In 1925, Werner Heisenberg and Erwin Schrödinger formulated quantum mechanics, which explained the preceding quantum theories. The observation by Edwin Hubble
in 1929 that the speed at which galaxies recede positively correlates
with their distance, led to the understanding that the universe is
expanding, and the formulation of the Big Bang theory by Georges Lemaître.
Currently, general relativity and quantum mechanics are inconsistent
with each other, and efforts are underway to unify the two.
In 1938 Otto Hahn and Fritz Strassmanndiscovered nuclear fission with radiochemical methods, and in 1939 Lise Meitner and Otto Robert Frisch wrote the first theoretical interpretation of the fission process, which was later improved by Niels Bohr and John A. Wheeler. Further developments took place during World War II, which led to the practical application of radar and the development and use of the atomic bomb. Around this time, Chien-Shiung Wu was recruited by the Manhattan Project to help develop a process for separating uranium metal into U-235 and U-238 isotopes by Gaseous diffusion. She was an expert experimentalist in beta decay and weak interaction physics. Wu designed an experiment that enabled theoretical physicists Tsung-Dao Lee and Chen-Ning Yang to disprove the law of parity experimentally, winning them a Nobel Prize in 1957.
Though the process had begun with the invention of the cyclotron by Ernest O. Lawrence in the 1930s, physics in the postwar period entered into a phase of what historians have called "Big Science",
requiring massive machines, budgets, and laboratories in order to test
their theories and move into new frontiers. The primary patron of
physics became state governments, who recognized that the support of
"basic" research could often lead to technologies useful to both
military and industrial applications.
Watson and Crick used many aluminium templates like this one, which is the single base Adenine (A), to build a physical model of DNA in 1953.
In the early 20th century, the study of heredity became a major
investigation after the rediscovery in 1900 of the laws of inheritance
developed by Mendel.
The 20th century also saw the integration of physics and chemistry,
with chemical properties explained as the result of the electronic
structure of the atom. Linus Pauling's book on The Nature of the Chemical Bond used the principles of quantum mechanics to deduce bond angles in ever-more complicated molecules. Pauling's work culminated in the physical modelling of DNA, the secret of life (in the words of Francis Crick, 1953). In the same year, the Miller–Urey experiment demonstrated in a simulation of primordial processes, that basic constituents of proteins, simple amino acids, could themselves be built up from simpler molecules, kickstarting decades of research into the chemical origins of life. By 1953, James D. Watson and Francis Crick clarified the basic structure of DNA, the genetic material for expressing life in all its forms, building on the work of Maurice Wilkins and Rosalind Franklin, suggested that the structure of DNA was a double helix. In their famous paper "Molecular structure of Nucleic Acids" In the late 20th century, the possibilities of genetic engineering became practical for the first time, and a massive international effort began in 1990 to map out an entire human genome (the Human Genome Project). The discipline of ecology typically traces its origin to the synthesis of Darwinian evolution and Humboldtianbiogeography, in the late 19th and early 20th centuries. Equally important in the rise of ecology, however, were microbiology and soil science—particularly the cycle of life concept, prominent in the work Louis Pasteur and Ferdinand Cohn. The word ecology was coined by Ernst Haeckel,
whose particularly holistic view of nature in general (and Darwin's
theory in particular) was important in the spread of ecological
thinking. In the 1930s, Arthur Tansley and others began developing the field of ecosystem ecology, which combined experimental soil science with physiological concepts of energy and the techniques of field biology.
Neuroscience as a distinct discipline
The
understanding of neurons and the nervous system became increasingly
precise and molecular during the 20th century. For example, in 1952, Alan Lloyd Hodgkin and Andrew Huxley
presented a mathematical model for transmission of electrical signals
in neurons of the giant axon of a squid, which they called "action potentials", and how they are initiated and propagated, known as the Hodgkin–Huxley model. In 1961–1962, Richard FitzHugh and J. Nagumo simplified Hodgkin–Huxley, in what is called the FitzHugh–Nagumo model. In 1962, Bernard Katz modeled neurotransmission across the space between neurons known as synapses.
Beginning in 1966, Eric Kandel and collaborators examined biochemical
changes in neurons associated with learning and memory storage in Aplysia. In 1981 Catherine Morris and Harold Lecar combined these models in the Morris–Lecar model. Such increasingly quantitative work gave rise to numerous biological neuron models and models of neural computation. Neuroscience began to be recognized as a distinct academic discipline in its own right. Eric Kandel and collaborators have cited David Rioch, Francis O. Schmitt, and Stephen Kuffler as having played critical roles in establishing the field.
Plate tectonics
Alfred Wegener in Greenland in the winter of 1912–13. He is most remembered as the originator of continental drift hypothesis by suggesting in 1912 that the continents are slowly drifting around the Earth.
Geologists' embrace of plate tectonics
became part of a broadening of the field from a study of rocks into a
study of the Earth as a planet. Other elements of this transformation
include: geophysical studies of the interior of the Earth, the grouping of geology with meteorology and oceanography as one of the "earth sciences", and comparisons of Earth and the solar system's other rocky planets.
Applications
In terms of applications, a massive amount of new technologies were developed in the 20th century. Technologies such as electricity, the incandescent light bulb, the automobile and the phonograph, first developed at the end of the 19th century, were perfected and universally deployed. The first airplane flight occurred in 1903, and by the end of the century large airplanes such as the Boeing 777 and Airbus A330 flew thousands of miles in a matter of hours. The development of the television and computers
caused massive changes in the dissemination of information. Advances in
biology also led to large increases in food production, as well as the
elimination of diseases such as polio. Computer science, built upon a foundation of theoretical linguistics, discrete mathematics, and electrical engineering, studies the nature and limits of computation. Subfields include computability, computational complexity, database design, computer networking, artificial intelligence, and the design of computer hardware.
One area in which advances in computing have contributed to more
general scientific development is by facilitating large-scale archiving of scientific data.
Contemporary computer science typically distinguishes itself by
emphasising mathematical 'theory' in contrast to the practical emphasis
of software engineering.
In economics, John Maynard Keynes prompted a division between microeconomics and macroeconomics in the 1920s. Under Keynesian economics macroeconomic trends can overwhelm economic choices made by individuals. Governments should promote aggregate demand for goods as a means to encourage economic expansion. Following World War II, Milton Friedman created the concept of monetarism.
Monetarism focuses on using the supply and demand of money as a method
for controlling economic activity. In the 1970s, monetarism has adapted
into supply-side economics
which advocates reducing taxes as a means to increase the amount of
money available for economic expansion. Other modern schools of economic
thought are New Classical economics and New Keynesian economics.
New Classical economics was developed in the 1970s, emphasizing solid
microeconomics as the basis for macroeconomic growth. New Keynesian
economics was created partially in response to New Classical economics,
and deals with how inefficiencies in the market create a need for
control by a central bank or government.
Developments in psychology, sociology, and anthropology
Psychology in the 20th century saw a rejection of Freud's theories as being too unscientific, and a reaction against Edward Titchener's atomistic approach of the mind. This led to the formulation of behaviorism by John B. Watson, which was popularized by B.F. Skinner. Behaviorism proposed epistemologically
limiting psychological study to overt behavior, since that could be
reliably measured. Scientific knowledge of the "mind" was considered too
metaphysical, hence impossible to achieve. The final decades of the
20th century have seen the rise of cognitive science, which considers the mind as once again a subject for investigation, using the tools of psychology, linguistics, computer science, philosophy, and neurobiology. New methods of visualizing the activity of the brain, such as PET scans and CAT scans,
began to exert their influence as well, leading some researchers to
investigate the mind by investigating the brain, rather than cognition.
These new forms of investigation assume that a wide understanding of the
human mind is possible, and that such an understanding may be applied
to other research domains, such as artificial intelligence. Evolutionary theory was applied to behavior and introduced to anthropology and psychology through the works of cultural anthropologistNapoleon Chagnon and E.O. Wilson. Wilson's book Sociobiology: The New Synthesis discussed how evolutionary mechanisms shaped the behaviors of all living organisms, including humans. Decades later, John Tooby and Leda Cosmides would develop the discipline of evolutionary psychology.
American sociology in the 1940s and 1950s was dominated largely by Talcott Parsons,
who argued that aspects of society that promoted structural integration
were therefore "functional". This structural functionalism approach was
questioned in the 1960s, when sociologists came to see this approach as
merely a justification for inequalities present in the status quo. In
reaction, conflict theory
was developed, which was based in part on the philosophies of Karl
Marx. Conflict theorists saw society as an arena in which different
groups compete for control over resources. Symbolic interactionism also
came to be regarded as central to sociological thinking. Erving Goffman
saw social interactions as a stage performance, with individuals
preparing "backstage" and attempting to control their audience through impression management. While these theories are currently prominent in sociological thought, other approaches exist, including feminist theory, post-structuralism, rational choice theory, and postmodernism.
In the mid-20th century, much of the methodologies of earlier
anthropological and ethnographical study were reevaluated with an eye
towards research ethics, while at the same time the scope of
investigation has broadened far beyond the traditional study of
"primitive cultures".
21st century
Higgs boson
One possible signature of a Higgs boson from a simulated proton–proton collision. It decays almost immediately into two jets of hadrons and two electrons, visible as lines.