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Sunday, February 22, 2015

Evolutionary neuroscience


From Wikipedia, the free encyclopedia

Evolutionary neuroscience is an interdisciplinary scientific research field that studies the evolution of nervous systems. Evolutionary neuroscientists attempt to understand the evolution and natural history of nervous system structure and function. The field draws on concepts and findings from both neuroscience and evolutionary biology. Historically, most empirical work has been in the area of comparative neuroanatomy, and modern studies often make use of phylogenetic comparative methods. Selective breeding and experimental evolution approaches are also being used more frequently.[1]

Various lines of research have linked specific neurotransmitter pathways to particular categories of behavior. For example, the brain chemical serotonin plays a role in the development of violent tendencies. Other research strongly implicates dopamine in the control of locomotor behavior through its influences on motivation and reward.[2]

Conceptually and theoretically, the field is related to fields as diverse as comparative psychology, neuroethology, developmental neurobiology, evo-devo, behavioral ecology, biological anthropology, sociobiology, cognitive neuroscience, sociocultural evolution and evolutionary psychology.

History

The field began after the publication of Darwin's On the Origin of Species, but brain evolution was largely viewed at the time in relation to the incorrect scala naturae. The 1936 book The Comparative Anatomy of the Nervous System of Vertebrates Including Man by the Dutch neurologist C.U. Ariëns Kappers (first published in German in 1921) was a landmark publication in the field. Following the Evolutionary Synthesis, the study of comparative neuroanatomy was conducted with an evolutionary view, and modern studies incorporate developmental genetics.[3][4]

Serotonin

Some amount of aggression is often adaptive behavior in the natural world. However, excessive aggression can be maladaptive. Hostility and anger turn into violence usually when they are misinterpreted or when the hostile or angry individual is expressing aggression in a way not typical for that species. Experiments using wild rats and mice have described under what circumstance aggression turns into violence. Aggressive behaviors tend to increase after the individual had prevailed in several aggressive encounters. Also, after multiple social conflicts involving aggressive behavior, individuals can start to display offensive aggression. In examining highly aggressive rats and mice it was shown that they changed their initial defensive aggressive behavior to a more violent method. What could cause such a change in these animal models? The focus has been particularly on the neuro-transmission of serotonin. Serotonin, more than any other neurotransmitter system, has been found to contribute to the development of aggressive behavior. Serotonin concentrations in the brain are strongly positively correlated with animals learning aggressive behavior when engaged in mating, territory, and hierarchical conflicts. Serotonin has an inverse relationship when those individual are displaying violence.[1] Boer et al. (2009) state that as aggression experiences increase there is a decrease in serotonin levels. Serotonin levels are lowered only after an individual has engaged in aggressive behaviors. This can be attributed to the changes in the release of serotonin by specific neurons called auto receptors. When exterminators exposed these auto receptors to agonist, chemicals that bind to the receptor to produce a desired reaction, aggressive behavior declined. This would indicate that increasing receptor function is normal when the brain of an aggressive animal is in a heightened state. When this function is increased too much, violent behavior may occur. [2]

Researchers


Paleoneurology



From Wikipedia, the free encyclopedia


Paleoneurology is the study of brain evolution by analysis of brain endocasts to determine endocranial traits and volumes. Considered a subdivision of neuroscience, paleoneurology combines techniques from other fields of study including paleontology and archaeology. It reveals specific insight concerning human evolution. The cranium is unique in that it grows in response to the growth of brain tissue rather than genetic guidance, as is the case with bones that support movement. Fossil skulls and their endocasts can be compared to each other, to the skulls and fossils of recently deceased individuals, and even compared to those of other species to make inferences about functional anatomy, physiology and phylogeny. Paleoneurology is in large part influenced by developments in neuroscience as a whole; without substantial knowledge about current functionality, it would be impossible to make inferences about the functionality of ancient brains.[1]

Hominid paleoneurology refers specifically to the study of brain evolution by directly examining the fossil record of humans and their closest hominid relatives (defined as species more closely related to humans than chimpanzees).[2] Paleoneurologists analyze endocasts that reproduce details of the external morphology of brains that have been imprinted on the internal surfaces of skulls.[3]

History


Primate skull series

Humans have had a long interest in the brain and its functions. The first recorded study of the brain and its functions was from a papyrus text written by the ancient Egyptians during the 17th century BCE. The document details 48 medical ailments and makes references to how to deal with head wounds. Much later in the 6th century BCE the ancient Greeks began to focus on studies of the brain and the relationship between the optic nerve and the brain. Studies of brain evolution, however, did not come about until much later in human history.[4]

Comparative anatomy began its emergence in the latter part of the 19th century. Two main views of life sprung forth; rationalism and transcendentalism. These formed the basis for the thought of scientists in this period. Georges Cuvier and Étienne Geoffroy St. Hilaire were leaders in the new field of comparative anatomy. Cuvier believed in the ability to create a functional morphology based simply on empirical evidence. He stressed function of the organ must coincide with its form. Geoffroy, in contrast, put a heavy emphasis on intuition as a method of understanding. His thought was based on two principles: the principle of connections and the principle of unity of plan. Geoffroy was one of the first to look for homologies in organs across species, though he believed that this was evidence of a universal plan rather than descent with modification.[4]

The late part of the 19th century in comparative anatomy was heavily influenced by the work of Charles Darwin in the On the Origin of Species in 1859. This work completely changed the views of comparative anatomists. Within 8 years of Darwin's release of the Origin of Species, his views on descent from a common ancestor were widely accepted. This led to a shift in trying to understand how different parts of the brain evolved.[4] The next major innovation that helped to bring about paleoneurology was the microscope. Although the microscope was invented in the 17th century, it was only used in biology in the beginning in the late 19th century. The techniques of observing brain cells under a microscope took a long time to refine. In 1873, with this tool in hand, Camillo Golgi began to cellularly detail the brain and employ techniques to perfect axonal microscoping. Ludwig Edinger took advantage of this and came up with a new branch of anatomy called comparative neuroanatomy. Edinger held that vertebrates evolved in a linear progressive series. He also thought that changes in the brain were based on a series of additions and differentiations and that the most highly, complex brains were those that were the most encephalized.[5] The period of 1885-1935 was an explosion of ideas in comparative neuroanatomy. This era culminated in the publication of "The Comparative Anatomy of the Nervous System" by Arienns, Kappers, Huber, and Cosby. This paper influenced Tilly Edinger and she later became to founder of Paleoneurology.[4]

Tilly Edinger

Ottilie "Tilly" Edinger was born in Frankfurt, Germany in 1897. Her father Ludwig Edinger, himself a pioneer in comparative neurology, provided Tilly with invaluable exposure to his field and the scientific community at large. Tilly had many private tutors before attending Schiller-Schule, the only secondary school for girls in Frankfurt at that time. Tilly Edinger continued her schooling with university studies in zoology, geology, and paleontology. While preparing her doctoral dissertation, Edinger encountered a natural brain endocast of Nothosaurus, a marine reptile from the Mesozoic era. Edinger's first paper, published in 1921, centered on the characteristics of the Nothosaurus specimen. Prior to the publication of her work, inferences about the evolution of the vertebrate brain were made exclusively through comparative anatomy of extant fish, amphibian, reptile, bird, and mammal brains. Tilly Edinger's background in neurology and paleontology paved the way for her to integrate comparative anatomy and stratigraphic sequence, thus introducing the concept of time to neurology and creating the field of paleoneurology. The field was formally defined with the publication of Die fossilen Gehirne (Fossil Brains) in 1929 which compiled knowledge on the subject that had previously been scattered in a wide variety of journals and treated as isolated events.[6]
While still in Germany, Edinger began studying extant species from a paleoneurological perspective by making inferences about evolutionary brain development in seacows using stratigraphic and comparative anatomical evidence. Edinger continued her research in Nazi Germany until the night of November 9, 1938 when thousands of Jews were killed or imprisoned in what became known as Kristallnacht. Although a visa was not immediately available for immigration to the United States, with the help of friends and colleagues who valued her work, Edinger was able to immigrate to London where she translated German medical texts into English. Eventually her visa quota number was called and she was able to immigrate to the United States where she took on a position as a research fellow at Harvard's Museum of Comparative Zoology.[6]

Her contributions to the field of paleoneurology include determining the extent to which endocasts reflect the anatomy of ancient brains, the adequacy of comparative anatomy to interpret brain evolution, the ability of brain endocasts to predict the lifestyles of extinct organisms, and if brain size has increased over geological time; topics which are still being explored today. In her later years, Edinger corresponded with the next generation of paleoneurologists, which insured that the work from her 50 year career continued into the future. The pinnacle accomplishment of her career was the compilation of an annotated bibliography of paleoneurological papers published between 1804 and 1966. The bibliography, Paleoneurology 1804-1966, was completed and published by colleagues posthumously in 1975 due to the untimely death of Edinger from injuries sustained during a traffic accident in 1967.[6]

Conflict between Holloway and Falk

Paleoneurologists Ralph L. Holloway and Dean Falk disagree about the interpretation of a depression on the Australopithecus afarensis AL 162-28 endocast. Holloway argues that the depression is a result of lipping at the lambdoid suture and that the sulcal patterns indicate cerebral organization moving toward a more human pattern, while Falk insists that the depression is the lunate sulcus in a position that is indicative of an ape-like sulcal pattern. The debate between these two scientists is not hinged solely on the AL 162-28 endocast, but rather extends to all australopithecine fossils, with Holloway insisting on the presence of hominid sulcal features, and Falk maintaining that the features are pongid in nature. The debate between Holloway and Falk is so intense that between 1983 and 1985, they published four papers on the identification of the medial end of the lunate sulcus of the Taung endocast (Australopithecus africanus), which only further strengthened the division between each scientist's respective opinion. Although there have been no definitive conclusions about the fossils in question, many techniques were created or critically analyzed and refined as a result of the conflict. These new techniques in endocast analysis included the use of stereoplotting to transfer sulci between differently shaped endocasts, measurement of indexes from photographs rather than directly from specimens, and confounding of measurements taken directly from specimens and those taken from photographs.[3]

Brain Endocasts


Normal human brain CT scan

A brain endocast is the imprintation of the inner features of a cranium that captures the details created from pressure exerted on the skull by the brain itself. Endocasts can be formed naturally by sedimentation through the cranial foramina which becomes rock-hard due to calcium deposition over time, or artificially by creating a mold from silicon or latex that is then filled with plaster-of-Paris while sitting in a water bath to equalize forces and retain the original shape. Natural endocasts are very rare; most of those that are studied are the result of artificial methods. Although the name implies that it is a copy of the once living brain, endocasts rarely exhibit convolutions due to buffering by the pia mater, arachnoid mater, and dura mater that once surrounded and protected the brain tissue. Furthermore, not all endocasts are created from a complete cranial fossil and subsequently, the missing parts are approximated based on similar fossils. In some cases, fragments from several fossils of the same species are used to construct a single endocast.[7]

More recently, computed tomography has played a large role in reconstructing endocasts. The procedure is non-invasive and has the advantage of being able to analyze a fossil in record time with little risk of damaging the fossil under review. CT imaging is achieved through the application of x-rays to produce tomographs, or sectional density images, which are similar to the images produced during MRI scans.[8] CT scans use slices approximately 1 mm thick to reconstruct a virtual model of the specimen.[9] This method is especially useful when a fossil cranium is occupied by a natural endocast that cannot be removed without destroying the skeletal portions of the fossil. Because the cranium and its contents are of different densities, the endocranial cavity and its unique traits can be reconstructed virtually.[8]

Radiographic technique such as computed tomographic imaging, or CT scans, coupled with computer programing have been used to analyze brain endocasts from as early as 1906.[10] Recent development of advanced computer graphics technology have allowed scientists to more accurately analyze of brain endocasts. M. Vannier and G. Conroy of Washington University School of Medicine have developed a system that images and analyzes surface morphologies in 3D. Scientists are able to encode surface landmarks that allows them to analyze sulcal length, cortical asymmetries and volume.[11] Radiologist, paleoanthropologists, computer scientists in both the United States and Europe have collaborated to study such fossils using virtual techniques.[10]

Methods of research


Sagittal view of a human brain through MRI

Paleoneurology revolves around the analysis of endocasts. Much of this analysis is focused on interpreting sulcal patterns, which is difficult because traces are often hardly recognizable, and there are no clear landmarks to use as reference points. Furthermore, the only clear reference plane is the sagittal plane one, which is marked by distinct cerebral asymmetries. Since the obtaining of clear data from fossil details is usually very difficult, much debate arises over interpretations. Experience is often an important factor in endocast analysis.[1] Therefore, a large portion of the field of paleoneurology arises out of developing more detailed procedures that increase the resolution and the reliability of interpretations.

Overall brain volume

Statistical analysis of brain endocasts gives information on the increases in overall brain volume ("endocranial volume"). Because endocasts are not exact replicas, or exact casts, of a once-living brain, computer algorithms and CT scans are needed to calculate endocranial volume. The calculated endocranial volume includes the meninges, cerebrospinal fluid, and cranial nerves. Therefore, these volumes end up larger than the once-living brain.[4] This information is useful for calculating relative brain size, RBS, and encephalization quotient, EQ. The corresponding body weight of the subject must also be known to calculated RBS. RBS is calculated by dividing the weight of the brain by body weight. EQ can be determined several different ways depending on the data set used. For example, Holloway and Post calculate EQ by the following equation:
EQ=Brainweight0.12Bodyweight0.66[4]
Brain volume is prominent in the scientific literature for discussing taxonomic identification, behavioral complexity, intelligence, and dissimilar rates of evolution. In modern humans, cranial capacity can vary by as much as 1000 cc, without any correlation to behavior. This degree of variation is almost equivalent to the total increase in volume from australopithecine fossils to modern humans, and brings into question the validity of relying on cranial capacity as a measurement of sophistication.[12]

Many paleoneurologists measure cranial capacity via the submersion method, in which displacement of water in a beaker is taken as the volume of the endocast. Scientists who believe that this method is not accurate enough will use a similar procedure in which a beaker with a spout is filled until it is full. The water displaced by the endocast is then weighed to determine the endocast volume. Although both of these techniques are significantly more precise than previous methods, scientists are optimistic that more advanced techniques such as computed tomography will provide greater accuracy of volume measurements.[7]

Morphometric analysis

Morphometric analysis relies on chord and arc measurements of the endocast surface. Length, width, bregma-basion, and height meausrements of an endocast are taken with spreading calipers.[7] Frontal lobe, parietal lobe, and occipital lobe chord length (the length of the lobe at its widest point along the midsagittal plane) are measured using a dioptograph in which landmarks are projected onto a two-dimensional surface. Measurements may be skewed if the orientation of the endocast has not been properly determined before the dioptograph is made. Geometric morphometrics (systems of coordinates superimposed over the measurements of the endocast) are often applied to allow comparison between specimens of varying size. Measurements may also be taken in reference to Broca's area, height of the endocast at 25% intervals of the maximum length, and the vault module (mean of maximum length, width, and middle height).[13] Although other measurements may be taken, the choice of landmarks are not always consistent between studies.[7][13]

Convolution pattern and cerebral organization

Convolutions, the individual gyri and sulci that compose the folds of the brain, are the most difficult aspect of an endocast to accurately assess. The surface of the brain is often referred to as smooth and fuzzy, due to the meninges and vasculature that cover the brain's surface. It is possible to observe underlying gyri and sulci patterns if an endocast is accuratly or preserved, but the uncertainty associated with these patterns often leads to controversy.[1] Because the robust australopithecine fossils show these details, convolutions are included in the study of endocasts whenever appropriate.[7]

Asymmetry

The degree of asymmetry between right and left hemispheres is a point of interest to most paleoneurologists because it could be linked to handedness or language development of the specimen. Asymmetries occur due to hemispherical specialization and are observed in both a qualitative and quantitative manner. The unevenness of the hemispheres, known as a petalia, is characterized by a lobe that is wider and/or protruding beyond the contralateral lobe. For example, a right-handed person typically has larger left occipital lobe and right frontal lobes than the contralateral lobes.
Petalias also occur due to specialization in the communication centers of the frontal cortex of the brain in modern humans. Petalias in the occipital lobe are easier to detect than those in the frontal lobe.[7] Certain asymmetries have been documented on Homo erectus specimens such as the Homo redolfensis specimen from 1.8 million years ago that resemble the same asymmetries from modern humans.[4] Some gorillas have shown strong petalias, but they are not found in combination with other petalias as is almost always the case in humans. Scientists use the presence of petalias to show sophistication, but they are not a definitive indicator of evolution toward a more human brain.[7]

Meningeal Patterns

Although the meninges have no link to behavior, they are still studied within the realm of paleoneurology due to the high degree of conservation of meningeal patterns within a species which may serve as a way to determine taxonomy and phylogeny.[7]

Endocranial Vasculature

Because meningeal blood vessels comprise part of the outermost layer of the brain, they often leave vascular grooves in the cranial cavity that are captured in endocasts. Endocranial vasculature originates around the foramina in the skull and in a living body would supply blood to the calvaria and dura mater. The vasculature is so well preserved in some fossils that terminal branches of the circulatory system can be observed. Analysis of cranial vasculature concentrates on the anterior meningeal system of the frontal region, the middle meningeal system of the parieto-temporal and part of the anterior occipital region, and the cerebellar fossa system of the cerebellar region. In the course of hominid evolution, the middle meningeal system has undergone the most change. Although cranial vasculature has been exhaustively studied in the last century, there has been no consensus on an identification scheme for the branches and patterns of the vascular system resulting from little overlap of results between studies. As such, endocranial vasculature is better suited for inferring the amount of blood delivered to different parts of the brain.[14]

Relative lobe size

It is impossible to determine accurate location of the central or precentral sulci from an endocast. Still it can provide a rough idea of lobe sizes.[4]

Significance

The study of paleoneurology allows researchers to examine the evolutionary nature of human encephalization. Traditionally, paleoneurologists have focused on determining the volume of the ancient brain and the patterns that emerged among related species. By finding these measurements, researchers have been able to predict the average body weight of species. Endocasts also reveal traits of the ancient brain including relative lobe size, blood supply, and other general insight into the anatomy of evolving species.[4]

Limitations

While paleoneurology is useful in the study of brain evolution, certain limitations to the information this study provides do exist. The limited scale and completeness of the fossil record inhibits the ability of paleoneurology to accurately document the course of brain evolution.[15] Further, fossil preservation is necessary to ensure accuracy of the endocasts studied.[16]Weathering, erosion, and overall gradual disfiguration may alter the naturally recovered endocasts or endocasts created from existing fossils.[17] The morphology of the brain can also be difficult to both quanitfy and describe, further complicating the observations made from the study of endocasts.[16] Additionally, paleoneurology provides very little insight into the actual anatomy within the brains of species studied; the study of endocasts is limited to the external anatomy only. The relationship among endocranial traits remains elusive. Comparative paleoeneurology reveals mostly only differences in endocranial size among related species, such as Gorilla gorilla. Since there is no proven direct relationship between brain size and intelligence, only inferences can be made regarding the developing behavior of ancient relatives of the Homo genus.

These limitations of paleoneurology are currently being dealt with by the development of more advanced tools to refine the study of endocasts.

Studies of interest

Brain shape, intelligence, and cognitive performance

Recent studies by Emiliano Bruner, Manuel Martin-Loechesb, Miguel Burgaletac, and Roberto Colomc have investigated the connection between midsagittal brain shape and mental speed. This study incorporated human subjects' cognitive testing in relationship to extinct humans. They used 2D from 102 MRI-scanned young adult human for comparison. Such correlations are small, suggesting that the influence of midsagittal brain geometry on individual cognitive performance is negligible but still provides useful information of evolutionary traits of the brain. Areas associated with the parietal cortex appear to be involved in relationships between brain geometry and mental speed.[18]

Degenerative diseases and functional disorder

Scientist J. Ghika believes use of paleoneurology is the best way to analyze several neurodegeneration leading to diseases such as Parkinson's disease, dyskinesias, gait disorders, Paget's disease of bone, dysautonomia and so on. A past study by S.I. Rapoport on Alzheimer's disease in Homo sapiens has shown the importance in using a darwinian perspective to better understand this disease itself and its symptoms.[19] The aim is to determine the genetic mechanisms that lead to focal or asymmetrical brain atrophy resulting in syndromic presentations that affect gait, hand movements (any sort of locomotion), language, cognition, mood and behavior disorders. Most risk-factors for neurodegenerative disease places highest priority on aging as causation. Scientists and physicians together can use clinical signs and symptoms to classify different diseases according to the changes taking place in specific brain areas in Homo sapiens leading to physical disease.[20]

Archaeology


From Wikipedia, the free encyclopedia


Roman ruins, Lausanne, Switzerland.

Archaeology, or archeology,[1] is the study of human activity in the past, primarily through the recovery and analysis of the material culture and environmental data that they have left behind, which includes artifacts, architecture, biofacts (also known as eco-facts) and cultural landscapes (the archaeological record). Because archaeology employs a wide range of different procedures, it can be considered to be both a social science and a humanity,[2] and in the United States, it is thought of as a branch of anthropology,[3] although in Europe, it is viewed as a separate discipline.

Archaeology studies human prehistory and history from the development of the first stone tools in eastern Africa 4 million years ago up until recent decades.[4] (Archaeology does not include the discipline of paleontology). It is of most importance for learning about prehistoric societies, when there are no written records for historians to study, making up over 99% of total human history, from the Paleolithic until the advent of literacy in any given society.[2] Archaeology has various goals, which range from studying human evolution to cultural evolution and understanding culture history.[5]

The discipline involves surveying, excavation and eventually analysis of data collected to learn more about the past. In broad scope, archaeology relies on cross-disciplinary research. It draws upon anthropology, history, art history, classics, ethnology, geography,[6] geology,[7][8][9] linguistics, semiology, physics, information sciences, chemistry, statistics, paleoecology, paleontology, paleozoology, paleoethnobotany, and paleobotany.

Archaeology developed out of antiquarianism in Europe during the 19th century, and has since become a discipline practiced across the world. Since its early development, various specific sub-disciplines of archaeology have developed, including maritime archaeology, feminist archaeology and archaeoastronomy, and numerous different scientific techniques have been developed to aid archaeological investigation. Nonetheless, today, archaeologists face many problems, such as dealing with pseudoarchaeology, the looting of artifacts, a lack of public interest, and opposition to the excavation of human remains.

History

Antiquarians

The science of archaeology (from Greek ἀρχαιολογία, archaiologia from ἀρχαῖος, arkhaios, "ancient" and -λογία, -logia, "-logy")[10] grew out of the older multi-disciplinary study known as antiquarianism. Antiquarians studied history with particular attention to ancient artefacts and manuscripts, as well as historical sites. Antiquarianism focused on the empirical evidence that existed for the understanding of the past, encapsulated in the motto of the 18th-century antiquary, Sir Richard Colt Hoare, "We speak from facts not theory". Tentative steps towards the systematization of archaeology as a science took place during the Enlightenment era in Europe in the 17th and 18th centuries.[11]

In Europe, philosophical interest in the remains of Greco-Roman civilisation and the rediscovery of classical culture began in the late Middle Age. Flavio Biondo an Italian Renaissance humanist historian created a systematic guide to the ruins and topography of ancient Rome in the early 15th century for which he has been called an early founder of archeology. Antiquarians, including John Leland and William Camden, conducted surveys of the English countryside, drawing, describing and interpreting the monuments that they encountered.

First excavations


An early photograph of Stonehenge taken July 1877

One of the first sites to undergo archeological excavation was Stonehenge and other megalithic monuments in England. John Aubrey was a pioneer archaeologist who recorded numerous megalithic and other field monuments in southern England. He was also ahead of his time in the analysis of his findings. He attempted to chart the chronological stylistic evolution of handwriting, medieval architecture, costume, and shield-shapes.[12]

Excavations were also carried out in the ancient towns of Pompeii and Herculaneum, both of which had been covered by ash during the Eruption of Mount Vesuvius in AD 79. These excavations began in 1748 in Pompeii, while in Herculaneum they began in 1738. The discovery of entire towns, complete with utensils and even human shapes, as well the unearthing of ancient frescos, had a big impact throughout Europe.

However, prior to the development of modern techniques, excavations tended to be haphazard; the importance of concepts such as stratification and context were overlooked.[13]

Development of archaeological method


Artefacts discovered at the 1808 Bush Barrow excavation by Sir Richard Colt Hoare and William Cunnington.

The father of archaeological excavation was William Cunnington (1754–1810). He undertook excavations in Wiltshire from around 1798,[14] funded by Sir Richard Colt Hoare. Cunnington made meticulous recordings of neolithic and Bronze Age barrows, and the terms he used to categorise and describe them are still used by archaeologists today.[15]

One of the major achievements of 19th century archaeology was the development of stratigraphy. The idea of overlapping strata tracing back to successive periods was borrowed from the new geological and palaeontological work of scholars like William Smith, James Hutton and Charles Lyell. The application of stratigraphy to archaeology first took place with the excavations of prehistorical and Bronze Age sites. In the third and fourth decades of the 19th century, archaeologists like Jacques Boucher de Perthes and Christian Jürgensen Thomsen began to put the artifacts they had found in chronological order.

A major figure in the development of archaeology into a rigorous science was the army officer and ethnologist, Augustus Pitt Rivers,[16] who began excavations on his land in England in the 1880s. His approach was highly methodical by the standards of the time, and he is widely regarded as the first scientific archaeologist. He arranged his artefacts by type or "typologically, and within types by date or "chronologically". This style of arrangement, designed to highlight the evolutionary trends in human artefacts, was of enormous significance for the accurate dating of the objects. His most important methodological innovation was his insistence that all artefacts, not just beautiful or unique ones, be collected and catalogued.[17]

William Flinders Petrie is another man who may legitimately be called the Father of Archaeology. His painstaking recording and study of artefacts, both in Egypt and later in Palestine, laid down many of the ideas behind modern archaeological recording; he remarked that "I believe the true line of research lies in the noting and comparison of the smallest details." Petrie developed the system of dating layers based on pottery and ceramic findings, which revolutionized the chronological basis of Egyptology. Petrie was the first to scientifically investigate the Great Pyramid in Egypt during the 1880s.[18] He was also responsible for mentoring and training a whole generation of Egyptologists, including Howard Carter who went on to achieve fame with the discovery of the tomb of 14th-century BC pharaoh Tutankhamun.

Mortimer Wheeler pioneered systematic excavation in the early 20th century. Pictured, are his excavations at Maiden Castle, Dorset, in October 1937.

The first stratigraphic excavation to reach wide popularity with public was that of Hissarlik, on the site of ancient Troy, carried out by Heinrich Schliemann, Frank Calvert, Wilhelm Dörpfeld and Carl Blegen in the 1870s. These scholars individuated nine different cities that had overlapped with one another, from prehistory to the Hellenistic period.[19] Meanwhile, the work of Sir Arthur Evans at Knossos in Crete revealed the ancient existence of an equally advanced Minoan civilization.[20]

The next major figure in the development of archaeology was Sir Mortimer Wheeler, whose highly disciplined approach to excavation and systematic coverage in the 1920s and 1930s brought the science on swiftly. Wheeler developed the grid system of excavation, which was further improved by his student Kathleen Kenyon.

Archaeology became a professional activity in the first half of the 20th century, and it became possible to study archaeology as a subject in universities and even schools. By the end of the 20th century nearly all professional archaeologists, at least in developed countries, were graduates. Further adaptation and innovation in archaeology continued in this period, when maritime archaeology and urban archaeology became more prevalent and rescue archaeology was developed as a result of increasing commercial development.[21]

Purpose


Cast of the skull of the Taung child, uncovered in South Africa. The Child was an infant of the Australopithecus africanus species, an early form of hominin

The purpose of archaeology is to learn more about past societies and the development of the human race. Over 99% of the development of humanity has occurred within prehistoric cultures, who did not make use of writing, thereby not leaving written records of themselves that can be studied today. Without such written sources, the only way to learn about prehistoric societies is to use archaeology. Many important developments in human history occurred during prehistory, such as the evolution of humanity during the Paleolithic period, when the hominins developed from the australopithecines in Africa and eventually into modern Homo sapiens. Archaeology also sheds light on many of humanity's technological advances, for instance the ability to use fire, the development of stone tools, the discovery of metallurgy, the beginnings of religion and the creation of agriculture. Without archaeology, we would know little or nothing about the use of material culture by humanity that pre-dates writing.[22]

However, it is not only prehistoric, pre-literate cultures that can be studied using archaeology but historic, literate cultures as well, through the sub-discipline of historical archaeology. For many literate cultures, such as Ancient Greece and Mesopotamia, their surviving records are often incomplete and biased to some extent. In many societies, literacy was restricted to the elite classes, such as the clergy or the bureaucracy of court or temple. The literacy even of aristocrats has sometimes been restricted to deeds and contracts. The interests and world-view of elites are often quite different from the lives and interests of the populace. Writings that were produced by people more representative of the general population were unlikely to find their way into libraries and be preserved there for posterity. Thus, written records tend to reflect the biases, assumptions, cultural values and possibly deceptions of a limited range of individuals, usually a small fraction of the larger population. Hence, written records cannot be trusted as a sole source. The material record may be closer to a fair representation of society, though it is subject to its own biases, such as sampling bias and differential preservation.[23]

Theory


There is no one singular approach to archaeological theory that has been adhered to by all archaeologists. When archaeology developed in the late 19th century, the first approach to archaeological theory to be practiced was that of cultural-history archaeology, which held the goal of explaining why cultures changed and adapted rather than just highlighting the fact that they did, therefore emphasizing historical particularism.[24] In the early 20th century, many archaeologists who studied past societies with direct continuing links to existing ones (such as those of Native Americans, Siberians, Mesoamericans etc.) followed the direct historical approach, compared the continuity between the past and contemporary ethnic and cultural groups.[24] In the 1960s, an archaeological movement largely led by American archaeologists like Lewis Binford and Kent Flannery arose that rebelled against the established cultural-history archaeology.[25][26] They proposed a "New Archaeology", which would be more "scientific" and "anthropological", with hypothesis testing and the scientific method very important parts of what became known as processual archaeology.[24]

In the 1980s, a new postmodern movement arose led by the British archaeologists Michael Shanks,[27][28][29][30] Christopher Tilley,[31] Daniel Miller,[32][33] and Ian Hodder,[34][35][36][37][38][39] which has become known as post-processual archaeology. It questioned processualism's appeals to scientific positivism and impartiality, and emphasized the importance of a more self-critical theoretical reflexivity.[citation needed] However, this approach has been criticized by processualists as lacking scientific rigor, and the validity of both processualism and post-processualism is still under debate. Meanwhile, another theory, known as historical processualism has emerged seeking to incorporate a focus on process and post-processual archaeology's emphasis of reflexivity and history.[40]

Archaeological theory now borrows from a wide range of influences, including neo-Darwinian evolutionary thought, phenomenology, postmodernism, agency theory, cognitive science, Structural functionalism, gender-based and Feminist archaeology, and Systems theory.

Methods

An archaeological investigation usually involves several distinct phases, each of which employs its own variety of methods. Before any practical work can begin, however, a clear objective as to what the archaeologists are looking to achieve must be agreed upon. This done, a site is surveyed to find out as much as possible about it and the surrounding area. Second, an excavation may take place to uncover any archaeological features buried under the ground. And, third, the data collected from the excavation is studied and evaluated in an attempt to achieve the original research objectives of the archaeologists. It is then considered good practice for the information to be published so that it is available to other archaeologists and historians, although this is sometimes neglected.[41]

Remote sensing

Before actually starting to dig in a location, satellite imagery can be used to look where sites are located within a large area.[42]

Field survey

Monte Alban archaeological site

The archaeological project then continues (or alternatively, begins) with a field survey. Regional survey is the attempt to systematically locate previously unknown sites in a region. Site survey is the attempt to systematically locate features of interest, such as houses and middens, within a site. Each of these two goals may be accomplished with largely the same methods.

Survey was not widely practiced in the early days of archaeology. Cultural historians and prior researchers were usually content with discovering the locations of monumental sites from the local populace, and excavating only the plainly visible features there. Gordon Willey pioneered the technique of regional settlement pattern survey in 1949 in the Viru Valley of coastal Peru,[43][44] and survey of all levels became prominent with the rise of processual archaeology some years later.[45]

Survey work has many benefits if performed as a preliminary exercise to, or even in place of, excavation. It requires relatively little time and expense, because it does not require processing large volumes of soil to search out artifacts. (Nevertheless, surveying a large region or site can be expensive, so archaeologists often employ sampling methods.)[46] As with other forms of non-destructive archaeology, survey avoids ethical issues (of particular concern to descendant peoples) associated with destroying a site through excavation. It is the only way to gather some forms of information, such as settlement patterns and settlement structure. Survey data are commonly assembled into maps, which may show surface features and/or artifact distribution.

Inverted kite aerial photo of an excavation of a Roman building at Nesley near Tetbury in Gloucestershire.

The simplest survey technique is surface survey. It involves combing an area, usually on foot but sometimes with the use of mechanized transport, to search for features or artifacts visible on the surface. Surface survey cannot detect sites or features that are completely buried under earth, or overgrown with vegetation. Surface survey may also include mini-excavation techniques such as augers, corers, and shovel test pits. If no materials are found, the area surveyed is deemed sterile.

Aerial survey is conducted using cameras attached to airplanes, balloons, or even Kites.[47] A bird's-eye view is useful for quick mapping of large or complex sites. Aerial photographs are used to document the status of the archaeological dig. Aerial imaging can also detect many things not visible from the surface. Plants growing above a buried man made structure, such as a stone wall, will develop more slowly, while those above other types of features (such as middens) may develop more rapidly. Photographs of ripening grain, which changes colour rapidly at maturation, have revealed buried structures with great precision. Aerial photographs taken at different times of day will help show the outlines of structures by changes in shadows. Aerial survey also employs ultraviolet, infrared, ground-penetrating radar wavelengths, LiDAR and thermography.[48]

Geophysical survey can be the most effective way to see beneath the ground. Magnetometers detect minute deviations in the Earth's magnetic field caused by iron artifacts, kilns, some types of stone structures, and even ditches and middens. Devices that measure the electrical resistivity of the soil are also widely used. Archaeological features whose electrical resistivity contrasts with that of surrounding soils can be detected and mapped. Some archaeological features (such as those composed of stone or brick) have higher resistivity than typical soils, while others (such as organic deposits or unfired clay) tend to have lower resistivity.

Although some archaeologists consider the use of metal detectors to be tantamount to treasure hunting, others deem them an effective tool in archaeological surveying. Examples of formal archaeological use of metal detectors include musketball distribution analysis on English Civil War battlefields, metal distribution analysis prior to excavation of a 19th-century ship wreck, and service cable location during evaluation. Metal detectorists have also contributed to archaeology where they have made detailed records of their results and refrained from raising artifacts from their archaeological context. In the UK, metal detectorists have been solicited for involvement in the Portable Antiquities Scheme.

Regional survey in underwater archaeology uses geophysical or remote sensing devices such as marine magnetometer, side-scan sonar, or sub-bottom sonar.[49]

Excavation

Excavations at the 3800-year-old Edgewater Park Site, Iowa

Archaeological excavation that discovered prehistoric caves in Vill (Innsbruck), Austria

An archaeologist sifting for POW remains on Wake Island.

Archaeological excavation existed even when the field was still the domain of amateurs, and it remains the source of the majority of data recovered in most field projects. It can reveal several types of information usually not accessible to survey, such as stratigraphy, three-dimensional structure, and verifiably primary context.

Modern excavation techniques require that the precise locations of objects and features, known as their provenance or provenience, be recorded. This always involves determining their horizontal locations, and sometimes vertical position as well (also see Primary Laws of Archaeology). Likewise, their association, or relationship with nearby objects and features, needs to be recorded for later analysis. This allows the archaeologist to deduce which artifacts and features were likely used together and which may be from different phases of activity. For example, excavation of a site reveals its stratigraphy; if a site was occupied by a succession of distinct cultures, artifacts from more recent cultures will lie above those from more ancient cultures.

Excavation is the most expensive phase of archaeological research, in relative terms. Also, as a destructive process, it carries ethical concerns. As a result, very few sites are excavated in their entirety. Again the percentage of a site excavated depends greatly on the country and "method statement" issued. In places 90% excavation is common. Sampling is even more important in excavation than in survey. It is common for large mechanical equipment, such as backhoes (JCBs), to be used in excavation, especially to remove the topsoil (overburden), though this method is increasingly used with great caution. Following this rather dramatic step, the exposed area is usually hand-cleaned with trowels or hoes to ensure that all features are apparent.

The next task is to form a site plan and then use it to help decide the method of excavation. Features dug into the natural subsoil are normally excavated in portions to produce a visible archaeological section for recording. A feature, for example a pit or a ditch, consists of two parts: the cut and the fill. The cut describes the edge of the feature, where the feature meets the natural soil. It is the feature's boundary. The fill is what the feature is filled with, and will often appear quite distinct from the natural soil. The cut and fill are given consecutive numbers for recording purposes. Scaled plans and sections of individual features are all drawn on site, black and white and colour photographs of them are taken, and recording sheets are filled in describing the context of each. All this information serves as a permanent record of the now-destroyed archaeology and is used in describing and interpreting the site.

Analysis

Once artifacts and structures have been excavated, or collected from surface surveys, it is necessary to properly study them, to gain as much data as possible. This process is known as post-excavation analysis, and is usually the most time-consuming part of the archaeological investigation. It is not uncommon for the final excavation reports on major sites to take years to be published.
At its most basic, the artifacts found are cleaned, cataloged and compared to published collections, to classify them typologically and to identify other sites with similar artifact assemblages. However, a much more comprehensive range of analytical techniques are available through archaeological science, meaning that artifacts can be dated and their compositions examined. The bones, plants and pollen collected from a site can all be analyzed (using the techniques of zooarchaeology, paleoethnobotany, and palynology), while any texts can usually be deciphered.

These techniques frequently provide information that would not otherwise be known and therefore contribute greatly to the understanding of a site.

Virtual archaeology

Some time around 1995 archaeologists started using computer graphics to build virtual 3D models of sites such as the throne room of an ancient Assyrian palace or ancient Rome.[50] This is done by collecting normal photographs and using computer graphics to build the virtual 3D model.[50] In more general terms, computers can be used to recreate the environment and conditions of the past, such as objects, buildings, landscapes and even ancient battles.[50] Computer simulation can be used to simulate the living conditions of an ancient community and to see how it would have reacted to various scenarios (such as how much food to grow, how many animals to slaughter, etc.)[50] 
Computer-built topographical models have been combined with astronomical calculations to verify whether or not certain structures (such as pillars) were aligned with astronomical events such as the sun's position at a solstice.[50]

Drones

In Peru archaeologists use drones to speed up survey work and protect sites from squatters, builders and miners. Small drones helped researchers produce three-dimensional models of Peruvian sites instead of the usual flat maps – and in days and weeks instead of months and years.[51]
Drones have replaced expensive and clumsy small planes, kites and helium balloons. Drones costing as little as £650 have proven useful. In 2013 drones have flown over at least six Peruvian archaeological sites, including the colonial Andean town Machu Llacta 4,000 metres (13,000 ft) above sea level. The drones continue to have altitude problems in the Andes, leading to plans to make a drone blimp, employing open source software.[51]

Jeffrey Quilter, an archaeologist with Harvard University said, "You can go up three metres and photograph a room, 300 metres and photograph a site, or you can go up 3,000 metres and photograph the entire valley."[51]

In September 2014 drones weighing about 5 kg (11 lb) were used for 3D mapping of the above-ground ruins of the Greek city of Aphrodisias. The data is being analysed by the Austrian Archaeological Institute in Vienna.[52]

Academic sub-disciplines

As with most academic disciplines, there are a very large number of archaeological sub-disciplines characterised by a specific method or type of material (e.g., lithic analysis, music, archaeobotany), geographical or chronological focus (e.g. Near Eastern archaeology, Islamic archaeology, Medieval archaeology), other thematic concern (e.g. maritime archaeology, landscape archaeology, battlefield archaeology), or a specific archaeological culture or civilization (e.g. Egyptology, Indology, Sinology).

Historical archaeology

Historical archaeology is the study of cultures with some form of writing.

In England, archaeologists have uncovered the long-lost layouts of medieval villages abandoned after crises of the 14th century (such as the Black Death) and the equally lost layouts of 17th-century parterre gardens swept away by a change in fashion.[citation needed] In downtown New York City archaeologists have exhumed the 18th century remains of the African burial ground.

Ethnoarchaeology

Ethnoarchaeology is the archaeological study of living people.[53][54][55][56][57][58] The approach gained notoriety during the emphasis on middle range theory that was a feature of the processual movement of the 1960s. Early ethnoarchaeological research focused on hunting and gathering or foraging societies. Ethnoarchaeology continues to be a vibrant component of post-processual and other current archaeological approaches.[59][60][61][62] Ethnoarchaeology is the use of ethnography to increase and improve analogs, which are then used as analogies to interpret the archaeological record. In short, ethnoarchaeology is the application of ethnography to archaeology.[63]

Experimental archaeology

Experimental archaeology represents the application of the experimental method to develop more highly controlled observations of processes that create and impact the archaeological record.[64][65][66][67][68] In the context of the logical positivism of processualism with its goals of improving the scientific rigor of archaeological epistemologies the experimental method gained importance. 
Experimental techniques remain a crucial component to improving the inferential frameworks for interpreting the archaeological record.

Archaeometry

Archaeometry is a field of study that aims to systematize archaeological measurement. It emphasizes the application of analytical techniques from physics, chemistry, and engineering. It is a field of research that frequently focuses on the definition of the chemical composition of archaeological remains for source analysis.[69] Archaeometry also investigates different spatial characteristics of features, employing methods such as space syntax techniques and geodesy as well as computer-based tools such as geographic information system technology.[70] Rare earth elements patterns may also be used.[71] A relatively nascent subfield is that of archaeological materials, designed to enhance understanding of prehistoric and non-industrial culture through scientific analysis of the structure and properties of materials associated with human activity.[72]

Cultural resources management

While archaeology can be done as a pure science, it can also be an applied science, namely the study of archaeological sites that are threatened by development. In such cases, archaeology is a subsidiary activity within Cultural resources management (CRM), also called heritage management in the United Kingdom.[73] Today, CRM accounts for most of the archaeological research done in the United States and much of that in western Europe as well. In the US, CRM archaeology has been a growing concern since the passage of the National Historic Preservation Act (NHPA) of 1966, and most taxpayers, scholars, and politicians believe that CRM has helped preserve much of that nation's history and prehistory that would have otherwise been lost in the expansion of cities, dams, and highways. Along with other statutes, the NHPA mandates that projects on federal land or involving federal funds or permits consider the effects of the project on each archaeological site.

The application of CRM in the United Kingdom is not limited to government-funded projects. Since 1990 PPG 16[74] has required planners to consider archaeology as a material consideration in determining applications for new development. As a result, numerous archaeological organisations undertake mitigation work in advance of (or during) construction work in archaeologically sensitive areas, at the developer's expense.

In England, ultimate responsibility of care for the historic environment rests with the Department for Culture, Media and Sport[75] in association with English Heritage.[76] In Scotland, Wales and Northern Ireland, the same responsibilities lie with Historic Scotland,[77] Cadw[78] and the Northern Ireland Environment Agency[79] respectively.

Among the goals of CRM are the identification, preservation, and maintenance of cultural sites on public and private lands, and the removal of culturally valuable materials from areas where they would otherwise be destroyed by human activity, such as proposed construction. This study involves at least a cursory examination to determine whether or not any significant archaeological sites are present in the area affected by the proposed construction. If these do exist, time and money must be allotted for their excavation. If initial survey and/or test excavation indicates the presence of an extraordinarily valuable site, the construction may be prohibited entirely. CRM is a thriving entity, especially in the United States and Europe where archaeologists from private companies and all levels of government engage in the practice of their discipline.

Cultural resources management has, however, been criticized. CRM is conducted by private companies that bid for projects by submitting proposals outlining the work to be done and an expected budget. It is not unheard-of for the agency responsible for the construction to simply choose the proposal that asks for the least funding. CRM archaeologists face considerable time pressure, often being forced to complete their work in a fraction of the time that might be allotted for a purely scholarly endeavor. Compounding the time pressure is the vetting process of site reports that are required (in the US) to be submitted by CRM firms to the appropriate State Historic Preservation Office (SHPO). From the SHPO's perspective there is to be no difference between a report submitted by a CRM firm operating under a deadline, and a multi-year academic project. The end result is that for a Cultural Resource Management archaeologist to be successful, they must be able to produce academic quality documents at a corporate world pace.

The annual ratio of open academic archaeology positions (inclusive of Post-Doc, temporary, and non tenure track appointments) to the annual number of archaeology MA/MSc and PhD students is grossly disproportionate. This dearth of academic positions causes a predictable excess of well educated individuals who join the ranks of the following year's crop of non-academically employed archaeologists. Cultural Resource Management, once considered an intellectual backwater for individuals with "strong backs and weak minds"[80] has reaped the benefit of this massive pool of well educated professionals. This results in CRM offices increasingly staffed by advance degreed individuals with a track record of producing scholarly articles but who have the notches on their trowels to show they have been in the trenches as a shovelbum.

Popular views of archaeology


Extensive excavations at Beit She'an, Israel

Permanent exhibition in a German multi-storey car park, explaining the archaeological discoveries made during the construction of this building

Early archaeology was largely an attempt to uncover spectacular artifacts and features, or to explore vast and mysterious abandoned cities. Early archaeology was mostly done by upper class, scholarly men. This generalization laid the foundation for the modern popular view of archaeology and archaeologists. This generalization has been with western culture for a long time. Another popular thought that dates back to this era is that archaeology is monetarily lucrative. A large majority of the general public is under the impression that excavations are undertaken for money and not historical data.[citation needed] It is easy for the general public to hold this notion for that is what is presented to them through general media, and has been for many decades.

The majority of the public view archaeology as being something only available to a narrow demographic. The job of archaeologist is depicted as a "romantic adventurist occupation".[81] To generalize, the public views archaeology as a fantasized hobby more than a job in the scientific community. The audience may not take away scientific methods from popular cinema but they do form a notion of "who archaeologists are, why they do what they do, and how relationships to the past are constituted".[81] The modern depiction of archaeology is sensationalized so much that it has incorrectly formed the public's perception of what archaeology is. The public is often under the impression that all archaeology takes place in a distant and foreign land, only to collect monetarily or spiritually priceless artifacts.

Such pursuits continue to fascinate the public. Books, films, and video games, such as Indiana Jones, King Solomon's Mines, The City of Brass, Relic Hunter, The Mummy, Stargate, and Tomb Raider all testify to the public's interest in the discovery aspect of archaeology.

Indeed it is a widely held belief that the general public takes many of their stereotypical ideals of archaeologists and archaeology from these films. The Indiana Jones movies have put forth the image of the able-bodied white western male who is comfortable in both the classroom and holding his own against baddies, and while Indiana Jones scholars like to point to this real life archaeologist and that one as the prototype for the character it is likely that coming up with a character who is a rugged, sexually appealing male that is smart enough to have a doctorate and can still save your life while under extreme peril could not have been difficult for screenwriters.[82] While the Lara Croft: Tomb Raider movies and video games stereotype female archaeologists as needing to be wealthy and fit and have a parent who carried weight in their field to be successful, as she is not considered herself to be an archaeologist so much as she is a treasure hunter. From the original 1932 Mummy film with Boris Karloff the viewing public is first shown the idea of archaeology taking place in a distant land on film, an idea which continued throughout all of the above films. There are subsequently numerous movies which all take place in warm and exotic locales, including all four Indiana Jones movies both Tomb Raider movies and three more mummy films after the franchise was re-imagined.

So while it is clear that film makers are at the very least drawing attention to archaeology in a way that other sciences cannot boast,there is certainly a very real disconnect between where archaeology is actually practiced (all over the world, often in mud or snow as often as in the sandy deserts) and by whom it is done these days (primarily young women seems to be the answer). Archaeology in popular culture is arguably thriving, and will likely continue to do so in the form of highly exaggerated films as that is what the public want. It therefor remains the job of the everyday archaeology to inform their students about the grand tradition of these films and to show them the parallels that will ultimately draw new scientists into the field of archaeology.

Much thorough and productive research has indeed been conducted in dramatic locales such as Copán and the Valley of the Kings, but the bulk of activities and finds of modern archaeology are not so sensational. Archaeological adventure stories tend to ignore the painstaking work involved in carrying out modern surveys, excavations, and data processing. Some archaeologists refer to such off-the-mark portrayals as "pseudoarchaeology".[83]

Archaeology has been portrayed in the mainstream media in sensational ways. This has its advantages and disadvantages. Many practitioners point to the childhood excitement of Indiana Jones films as their inspiration to enter the field.[84][85] Archaeologists are also very much reliant on public support; the question of exactly who they are doing their work for is often discussed.[86]

Current issues and controversy

Public archaeology


Excavations at the site of Gran Dolina, in the Atapuerca Mountains, Spain, 2008

Motivated by a desire to halt looting, curb pseudoarchaeology, and to help preserve archaeological sites through education and fostering public appreciation for the importance of archaeological heritage, archaeologists are mounting public-outreach campaigns.[87] They seek to stop looting by combatting people who illegally take artifacts from protected sites, and by alerting people who live near archaeological sites of the threat of looting. Common methods of public outreach include press releases, and the encouragement of school field trips to sites under excavation by professional archaeologists.[citation needed] Public appreciation of the significance of archaeology and archaeological sites often leads to improved protection from encroaching development or other threats.

One audience for archaeologists' work is the public. They increasingly realize that their work can benefit non-academic and non-archaeological audiences, and that they have a responsibility to educate and inform the public about archaeology. Local heritage awareness is aimed at increasing civic and individual pride through projects such as community excavation projects, and better public presentations of archaeological sites and knowledge.[citation needed] The U.S.Dept. of Agriculture, Forest Service (USFS) operates a volunteer archaeology and historic preservation program called the Passport in Time (PIT). Volunteers work with professional USFS archaeologists and historians on national forests throughout the U.S. Volunteers are involved in all aspects of professional archaeology under expert supervision.[88]

In the UK, popular archaeology programs such as Time Team and Meet the Ancestors have resulted in a huge upsurge in public interest.[citation needed] Where possible, archaeologists now make more provisions for public involvement and outreach in larger projects than they once did, and many local archaeological organizations operate within the Community archaeology framework to expand public involvement in smaller-scale, more local projects. Archaeological excavation, however, is best undertaken by well-trained staff that can work quickly and accurately. Often this requires observing the necessary health and safety and indemnity insurance issues involved in working on a modern building site with tight deadlines. Certain charities and local government bodies sometimes offer places on research projects either as part of academic work or as a defined community project.[citation needed] There is also a flourishing industry selling places on commercial training excavations and archaeological holiday tours.[citation needed]

Archaeologists prize local knowledge and often liaise with local historical and archaeological societies, which is one reason why Community archaeology projects are starting to become more common. Often archaeologists are assisted by the public in the locating of archaeological sites, which professional archaeologists have neither the funding, nor the time to do.

The Archaeological Legacy Institute (ALI), self-described as "an independent, nonprofit, tax-exempt (501[c][3])", is a research and education corporation registered in Oregon in 1999. The ALI founded an online Archaeology Channel to support the organization's mission "to develop ways to make archaeology more effective both in gathering important information about past human lifeways and in delivering that information to the public and the profession."[89]

Pseudoarchaeology

Pseudoarchaeology is an umbrella term for all activities that falsely claim to be archaeological but in fact violate commonly accepted and scientific archaeological practices. It includes much fictional archaeological work (discussed above), as well as some actual activity. Many non-fiction authors have ignored the scientific methods of processual archaeology, or the specific critiques of it contained in post-processualism.
An example of this type is the writing of Erich von Däniken. His 1968 book, Chariots of the Gods?, together with many subsequent lesser-known works, expounds a theory of ancient contacts between human civilisation on Earth and more technologically advanced extraterrestrial civilisations. This theory, known as palaeocontact theory, or Ancient astronaut theory, is not exclusively Däniken's, nor did the idea originate with him. Works of this nature are usually marked by the renunciation of well-established theories on the basis of limited evidence, and the interpretation of evidence with a preconceived theory in mind.

Looting


A looter's pit on the morning following its excavation, taken at Rontoy, Huaura Valley, Peru in June 2007. Several small holes left by looters' prospecting probes can be seen, as well as their footprints.

Stela of a king named Adad-Nirari. Object stolen from the Iraq National Museum in the looting in connection with the Iraq war of 2003.

Looting of archaeological sites is an ancient problem. For instance, many of the tombs of the Egyptian pharaohs were looted during antiquity.[90] Archaeology stimulates interest in ancient objects, and people in search of artifacts or treasure cause damage to archaeological sites. The commercial and academic demand for artifacts unfortunately contributes directly to the illicit antiquities trade. Smuggling of antiquities abroad to private collectors has caused great cultural and economic damage in many countries whose governments lack the resources and or the will to deter it. Looters damage and destroy archaeological sites, denying future generations information about their ethnic and cultural heritage. Indigenous peoples especially lose access to and control over their 'cultural resources', ultimately denying them the opportunity to know their past.[91]

In 1937 W. F. Hodge the Director of the Southwest Museum released a statement that the museum would no longer purchase or accept collections from looted contexts.[92] The first conviction of the transport of artifacts illegally removed from private property under the Archaeological Resources Protection Act (ARPA; Public Law 96-95; 93 Statute 721; 16 U.S.C. § 470aamm) was in 1992 in the State of Indiana.[93]

Descendant peoples

In the United States, examples such as the case of Kennewick Man have illustrated the tensions between Native Americans and archaeologists, which can be summarized as a conflict between a need to remain respectful toward sacred burial sites and the academic benefit from studying them.
For years, American archaeologists dug on Indian burial grounds and other places considered sacred, removing artifacts and human remains to storage facilities for further study. In some cases human remains were not even thoroughly studied but instead archived rather than reburied. Furthermore, Western archaeologists' views of the past often differ from those of tribal peoples. The West views time as linear; for many natives, it is cyclic. From a Western perspective, the past is long-gone; from a native perspective, disturbing the past can have dire consequences in the present.

As a consequence of this, American Indians attempted to prevent archaeological excavation of sites inhabited by their ancestors, while American archaeologists believed that the advancement of scientific knowledge was a valid reason to continue their studies. This contradictory situation was addressed by the Native American Graves Protection and Repatriation Act (NAGPRA, 1990), which sought to reach a compromise by limiting the right of research institutions to possess human remains. Due in part to the spirit of postprocessualism, some archaeologists have begun to actively enlist the assistance of indigenous peoples likely to be descended from those under study.

Archaeologists have also been obliged to re-examine what constitutes an archaeological site in view of what native peoples believe to constitute sacred space. To many native peoples, natural features such as lakes, mountains or even individual trees have cultural significance. Australian archaeologists especially have explored this issue and attempted to survey these sites to give them some protection from being developed. Such work requires close links and trust between archaeologists and the people they are trying to help and at the same time study.

While this cooperation presents a new set of challenges and hurdles to fieldwork, it has benefits for all parties involved. Tribal elders cooperating with archaeologists can prevent the excavation of areas of sites that they consider sacred, while the archaeologists gain the elders' aid in interpreting their finds. There have also been active efforts to recruit aboriginal peoples directly into the archaeological profession.

Repatriation

A new trend in the heated controversy between First Nations groups and scientists is the repatriation of native artifacts to the original descendants. An example of this occurred June 21, 2005, when community members and elders from a number of the 10 Algonquian nations in the Ottawa area convened on the Kitigan Zibi reservation near Maniwaki, Quebec, to inter ancestral human remains and burial goods — some dating back 6,000 years. It was not determined, however, if the remains were directly related to the Algonquin people who now inhabit the region. The remains may be of Iroquoian ancestry, since Iroquoian people inhabited the area before the Algonquin. Moreover, the oldest of these remains might have no relation at all to the Algonquin or Iroquois, and belong to an earlier culture who previously inhabited the area.

The remains and artifacts, including jewelry, tools and weapons, were originally excavated from various sites in the Ottawa Valley, including Morrison and the Allumette Islands. They had been part of the Canadian Museum of Civilization's research collection for decades, some since the late 19th century. Elders from various Algonquin communities conferred on an appropriate reburial, eventually deciding on traditional redcedar and birchbark boxes lined with redcedar chips, muskrat and beaver pelts.

Now, an inconspicuous rock mound marks the reburial site where close to 80 boxes of various sizes are buried, no further scientific study is possible. Although negotiations were at times tense between the Kitigan Zibi community and museum, they were able to reach agreement.[94]

Kennewick Man is another repatriation candidate that has been the source of heated debate.

Operator (computer programming)

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