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Monday, August 21, 2023

Charles Babbage

From Wikipedia, the free encyclopedia
Charles Babbage

Babbage in 1860
Born26 December 1791
London, England
Died18 October 1871 (aged 79)
Marylebone, London, England
Alma materPeterhouse, Cambridge
Known forAnalytical engine
Difference engine
Spouse
Georgiana Whitmore
(m. 1814; died 1827)
Children8, including Benjamin Herschel Babbage
RelativesWilliam Wolryche-Whitmore (brother-in-law)
AwardsGold Medal of the Royal Astronomical Society (1824)
Scientific career
FieldsMathematics, engineering, political economy, computer science
InstitutionsTrinity College, Cambridge, Peterhouse, Cambridge
InfluencesRobert Woodhouse, Gaspard Monge, John Herschel
InfluencedKarl Marx, John Stuart Mill, Ada Lovelace

Charles Babbage KH FRS (/ˈbæbɪ/; 26 December 1791 – 18 October 1871) was an English polymath. A mathematician, philosopher, inventor and mechanical engineer, Babbage originated the concept of a digital programmable computer.

Babbage is considered by some to be "father of the computer". Babbage is credited with inventing the first mechanical computer, the Difference Engine, that eventually led to more complex electronic designs, though all the essential ideas of modern computers are to be found in Babbage's Analytical Engine, programmed using a principle openly borrowed from the Jacquard loom. Babbage had a broad range of interests in addition to his work on computers covered in his 1832 book Economy of Manufactures and Machinery. His varied work in other fields has led him to be described as "pre-eminent" among the many polymaths of his century.

Babbage, who died before the complete successful engineering of many of his designs, including his Difference Engine and Analytical Engine, remained a prominent figure in the ideating of computing. Parts of Babbage's incomplete mechanisms are on display in the Science Museum in London. In 1991, a functioning difference engine was constructed from Babbage's original plans. Built to tolerances achievable in the 19th century, the success of the finished engine indicated that Babbage's machine would have worked.

Early life

Portrait of Charles Babbage (c. 1820)

Babbage's birthplace is disputed, but according to the Oxford Dictionary of National Biography he was most likely born at 44 Crosby Row, Walworth Road, London, England. A blue plaque on the junction of Larcom Street and Walworth Road commemorates the event.

His date of birth was given in his obituary in The Times as 26 December 1792; but then a nephew wrote to say that Babbage was born one year earlier, in 1791. The parish register of St. Mary's, Newington, London, shows that Babbage was baptised on 6 January 1792, supporting a birth year of 1791.

Babbage c. 1850

Babbage was one of four children of Benjamin Babbage and Betsy Plumleigh Teape. His father was a banking partner of William Praed in founding Praed's & Co. of Fleet Street, London, in 1801. In 1808, the Babbage family moved into the old Rowdens house in East Teignmouth. Around the age of eight, Babbage was sent to a country school in Alphington near Exeter to recover from a life-threatening fever. For a short time, he attended King Edward VI Grammar School in Totnes, South Devon, but his health forced him back to private tutors for a time.

Babbage then joined the 30-student Holmwood Academy, in Baker Street, Enfield, Middlesex, under the Reverend Stephen Freeman. The academy had a library that prompted Babbage's love of mathematics. He studied with two more private tutors after leaving the academy. The first was a clergyman near Cambridge; through him Babbage encountered Charles Simeon and his evangelical followers, but the tuition was not what he needed. He was brought home, to study at the Totnes school: this was at age 16 or 17. The second was an Oxford tutor, under whom Babbage reached a level in Classics sufficient to be accepted by the University of Cambridge.

At the University of Cambridge

Babbage arrived at Trinity College, Cambridge, in October 1810. He was already self-taught in some parts of contemporary mathematics; he had read Robert Woodhouse, Joseph Louis Lagrange, and Marie Agnesi. As a result, he was disappointed in the standard mathematical instruction available at the university.

Babbage, John Herschel, George Peacock, and several other friends formed the Analytical Society in 1812; they were also close to Edward Ryan. As a student, Babbage was also a member of other societies such as The Ghost Club, concerned with investigating supernatural phenomena, and the Extractors Club, dedicated to liberating its members from the madhouse, should any be committed to one.

In 1812, Babbage transferred to Peterhouse, Cambridge. He was the top mathematician there, but did not graduate with honours. He instead received a degree without examination in 1814. He had defended a thesis that was considered blasphemous in the preliminary public disputation, but it is not known whether this fact is related to his not sitting the examination.

After Cambridge

Considering his reputation, Babbage quickly made progress. He lectured to the Royal Institution on astronomy in 1815, and was elected a Fellow of the Royal Society in 1816. After graduation, on the other hand, he applied for positions unsuccessfully, and had little in the way of a career. In 1816 he was a candidate for a teaching job at Haileybury College; he had recommendations from James Ivory and John Playfair, but lost out to Henry Walter. In 1819, Babbage and Herschel visited Paris and the Society of Arcueil, meeting leading French mathematicians and physicists. That year Babbage applied to be professor at the University of Edinburgh, with the recommendation of Pierre Simon Laplace; the post went to William Wallace.

With Herschel, Babbage worked on the electrodynamics of Arago's rotations, publishing in 1825. Their explanations were only transitional, being picked up and broadened by Michael Faraday. The phenomena are now part of the theory of eddy currents, and Babbage and Herschel missed some of the clues to unification of electromagnetic theory, staying close to Ampère's force law.

Babbage purchased the actuarial tables of George Barrett, who died in 1821 leaving unpublished work, and surveyed the field in 1826 in Comparative View of the Various Institutions for the Assurance of Lives. This interest followed a project to set up an insurance company, prompted by Francis Baily and mooted in 1824, but not carried out. Babbage did calculate actuarial tables for that scheme, using Equitable Society mortality data from 1762 onwards.

During this whole period, Babbage depended awkwardly on his father's support, given his father's attitude to his early marriage, of 1814: he and Edward Ryan wedded the Whitmore sisters. He made a home in Marylebone in London and established a large family. On his father's death in 1827, Babbage inherited a large estate (value around £100,000, equivalent to £9.21 million or $12.6 million today), making him independently wealthy. After his wife's death in the same year he spent time travelling. In Italy he met Leopold II, Grand Duke of Tuscany, foreshadowing a later visit to Piedmont. In April 1828 he was in Rome, and relying on Herschel to manage the difference engine project, when he heard that he had become a professor at Cambridge, a position he had three times failed to obtain (in 1820, 1823 and 1826).

Royal Astronomical Society

Babbage was instrumental in founding the Royal Astronomical Society in 1820, initially known as the Astronomical Society of London. Its original aims were to reduce astronomical calculations to a more standard form, and to circulate data. These directions were closely connected with Babbage's ideas on computation, and in 1824 he won its Gold Medal, cited "for his invention of an engine for calculating mathematical and astronomical tables".

Babbage's motivation to overcome errors in tables by mechanisation had been a commonplace since Dionysius Lardner wrote about it in 1834 in the Edinburgh Review (under Babbage's guidance). The context of these developments is still debated. Babbage's own account of the origin of the difference engine begins with the Astronomical Society's wish to improve The Nautical Almanac. Babbage and Herschel were asked to oversee a trial project, to recalculate some part of those tables. With the results to hand, discrepancies were found. This was in 1821 or 1822, and was the occasion on which Babbage formulated his idea for mechanical computation. The issue of the Nautical Almanac is now described as a legacy of a polarisation in British science caused by attitudes to Sir Joseph Banks, who had died in 1820.

A portion of the difference engine

Babbage studied the requirements to establish a modern postal system, with his friend Thomas Frederick Colby, concluding there should be a uniform rate that was put into effect with the introduction of the Uniform Fourpenny Post supplanted by the Uniform Penny Post in 1839 and 1840. Colby was another of the founding group of the Society. He was also in charge of the Survey of Ireland. Herschel and Babbage were present at a celebrated operation of that survey, the remeasuring of the Lough Foyle baseline.

British Lagrangian School

The Analytical Society had initially been no more than an undergraduate provocation. During this period it had some more substantial achievements. In 1816 Babbage, Herschel and Peacock published a translation from French of the lectures of Sylvestre Lacroix, which was then the state-of-the-art calculus textbook.

Reference to Lagrange in calculus terms marks out the application of what are now called formal power series. British mathematicians had used them from about 1730 to 1760. As re-introduced, they were not simply applied as notations in differential calculus. They opened up the fields of functional equations (including the difference equations fundamental to the difference engine) and operator (D-module) methods for differential equations. The analogy of difference and differential equations was notationally changing Δ to D, as a "finite" difference becomes "infinitesimal". These symbolic directions became popular, as operational calculus, and pushed to the point of diminishing returns. The Cauchy concept of limit was kept at bay. Woodhouse had already founded this second "British Lagrangian School" with its treatment of Taylor series as formal.

In this context function composition is complicated to express, because the chain rule is not simply applied to second and higher derivatives. This matter was known to Woodhouse by 1803, who took from Louis François Antoine Arbogast what is now called Faà di Bruno's formula. In essence it was known to Abraham De Moivre (1697). Herschel found the method impressive, Babbage knew of it, and it was later noted by Ada Lovelace as compatible with the analytical engine. In the period to 1820 Babbage worked intensively on functional equations in general, and resisted both conventional finite differences and Arbogast's approach (in which Δ and D were related by the simple additive case of the exponential map). But via Herschel he was influenced by Arbogast's ideas in the matter of iteration, i.e. composing a function with itself, possibly many times. Writing in a major paper on functional equations in the Philosophical Transactions (1815/6), Babbage said his starting point was work of Gaspard Monge.

Academic

From 1828 to 1839, Babbage was Lucasian Professor of Mathematics at Cambridge. Not a conventional resident don, and inattentive to his teaching responsibilities, he wrote three topical books during this period of his life. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1832. Babbage was out of sympathy with colleagues: George Biddell Airy, his predecessor as Lucasian Professor of Mathematics at Trinity College, Cambridge, thought an issue should be made of his lack of interest in lecturing. Babbage planned to lecture in 1831 on political economy. Babbage's reforming direction looked to see university education more inclusive, universities doing more for research, a broader syllabus and more interest in applications; but William Whewell found the programme unacceptable. A controversy Babbage had with Richard Jones lasted for six years. He never did give a lecture.

It was during this period that Babbage tried to enter politics. Simon Schaffer writes that his views of the 1830s included disestablishment of the Church of England, a broader political franchise, and inclusion of manufacturers as stakeholders. He twice stood for Parliament as a candidate for the borough of Finsbury. In 1832 he came in third among five candidates, missing out by some 500 votes in the two-member constituency when two other reformist candidates, Thomas Wakley and Christopher Temple, split the vote. In his memoirs Babbage related how this election brought him the friendship of Samuel Rogers: his brother Henry Rogers wished to support Babbage again, but died within days. In 1834 Babbage finished last among four. In 1832, Babbage, Herschel and Ivory were appointed Knights of the Royal Guelphic Order, however they were not subsequently made knights bachelor to entitle them to the prefix Sir, which often came with appointments to that foreign order (though Herschel was later created a baronet).

"Declinarians", learned societies and the BAAS

Letter to Sir Humphry Davy, 1822

Babbage now emerged as a polemicist. One of his biographers notes that all his books contain a "campaigning element". His Reflections on the Decline of Science and some of its Causes (1830) stands out, however, for its sharp attacks. It aimed to improve British science, and more particularly to oust Davies Gilbert as President of the Royal Society, which Babbage wished to reform. It was written out of pique, when Babbage hoped to become the junior secretary of the Royal Society, as Herschel was the senior, but failed because of his antagonism to Humphry Davy. Michael Faraday had a reply written, by Gerrit Moll, as On the Alleged Decline of Science in England (1831). On the front of the Royal Society Babbage had no impact, with the bland election of the Duke of Sussex to succeed Gilbert the same year. As a broad manifesto, on the other hand, his Decline led promptly to the formation in 1831 of the British Association for the Advancement of Science (BAAS).

The Mechanics' Magazine in 1831 identified as Declinarians the followers of Babbage. In an unsympathetic tone it pointed out David Brewster writing in the Quarterly Review as another leader; with the barb that both Babbage and Brewster had received public money.

In the debate of the period on statistics (qua data collection) and what is now statistical inference, the BAAS in its Statistical Section (which owed something also to Whewell) opted for data collection. This Section was the sixth, established in 1833 with Babbage as chairman and John Elliot Drinkwater as secretary. The foundation of the Statistical Society followed. Babbage was its public face, backed by Richard Jones and Robert Malthus.

On the Economy of Machinery and Manufactures

On the Economy of Machinery and Manufactures, 1835
Babbage's notation for machine parts, explanation from On a method of expressing by signs the action of machinery (1827) of his "Mechanical Notation", invented for his own use in understanding the work on the difference engine, and an influence on the conception of the analytical engine

Babbage published On the Economy of Machinery and Manufactures (1832), on the organisation of industrial production. It was an influential early work of operational research. John Rennie the Younger in addressing the Institution of Civil Engineers on manufacturing in 1846 mentioned mostly surveys in encyclopaedias, and Babbage's book was first an article in the Encyclopædia Metropolitana, the form in which Rennie noted it, in the company of related works by John Farey Jr., Peter Barlow and Andrew Ure. From An essay on the general principles which regulate the application of machinery to manufactures and the mechanical arts (1827), which became the Encyclopædia Metropolitana article of 1829, Babbage developed the schematic classification of machines that, combined with discussion of factories, made up the first part of the book. The second part considered the "domestic and political economy" of manufactures.

The book sold well, and quickly went to a fourth edition (1836). Babbage represented his work as largely a result of actual observations in factories, British and abroad. It was not, in its first edition, intended to address deeper questions of political economy; the second (late 1832) did, with three further chapters including one on piece rate. The book also contained ideas on rational design in factories, and profit sharing.

"Babbage principle"

In Economy of Machinery was described what is now called the "Babbage principle". It pointed out commercial advantages available with more careful division of labour. As Babbage himself noted, it had already appeared in the work of Melchiorre Gioia in 1815. The term was introduced in 1974 by Harry Braverman. Related formulations are the "principle of multiples" of Philip Sargant Florence, and the "balance of processes".

What Babbage remarked is that skilled workers typically spend parts of their time performing tasks that are below their skill level. If the labour process can be divided among several workers, labour costs may be cut by assigning only high-skill tasks to high-cost workers, restricting other tasks to lower-paid workers. He also pointed out that training or apprenticeship can be taken as fixed costs; but that returns to scale are available by his approach of standardisation of tasks, therefore again favouring the factory system. His view of human capital was restricted to minimising the time period for recovery of training costs.

Publishing

Another aspect of the work was its detailed breakdown of the cost structure of book publishing. Babbage took the unpopular line, from the publishers' perspective, of exposing the trade's profitability. He went as far as to name the organisers of the trade's restrictive practices. Twenty years later he attended a meeting hosted by John Chapman to campaign against the Booksellers Association, still a cartel.

Influence

It has been written that "what Arthur Young was to agriculture, Charles Babbage was to the factory visit and machinery". Babbage's theories are said to have influenced the layout of the 1851 Great Exhibition, and his views had a strong effect on his contemporary George Julius Poulett Scrope. Karl Marx argued that the source of the productivity of the factory system was exactly the combination of the division of labour with machinery, building on Adam Smith, Babbage and Ure. Where Marx picked up on Babbage and disagreed with Smith was on the motivation for division of labour by the manufacturer: as Babbage did, he wrote that it was for the sake of profitability, rather than productivity, and identified an impact on the concept of a trade.

John Ruskin went further, to oppose completely what manufacturing in Babbage's sense stood for. Babbage also affected the economic thinking of John Stuart Mill. George Holyoake saw Babbage's detailed discussion of profit sharing as substantive, in the tradition of Robert Owen and Charles Fourier, if requiring the attentions of a benevolent captain of industry, and ignored at the time.

Works by Babbage and Ure were published in French translation in 1830; On the Economy of Machinery was translated in 1833 into French by Édouard Biot, and into German the same year by Gottfried Friedenberg.The French engineer and writer on industrial organisation Léon Lalanne was influenced by Babbage, but also by the economist Claude Lucien Bergery, in reducing the issues to "technology". William Jevons connected Babbage's "economy of labour" with his own labour experiments of 1870. The Babbage principle is an inherent assumption in Frederick Winslow Taylor's scientific management.

Mary Everest Boole claimed that there was profound influence – via her uncle George Everest – of Indian thought in general and Indian logic, in particular, on Babbage and on her husband George Boole, as well as on Augustus De Morgan:

Think what must have been the effect of the intense Hinduizing of three such men as Babbage, De Morgan, and George Boole on the mathematical atmosphere of 1830–65. What share had it in generating the Vector Analysis and the mathematics by which investigations in physical science are now conducted?

Natural theology

In 1837, responding to the series of eight Bridgewater Treatises, Babbage published his Ninth Bridgewater Treatise, under the title On the Power, Wisdom and Goodness of God, as manifested in the Creation. In this work Babbage weighed in on the side of uniformitarianism in a current debate. He preferred the conception of creation in which a God-given natural law dominated, removing the need for continuous "contrivance".

The book is a work of natural theology, and incorporates extracts from related correspondence of Herschel with Charles Lyell. Babbage put forward the thesis that God had the omnipotence and foresight to create as a divine legislator. In this book, Babbage dealt with relating interpretations between science and religion; on the one hand, he insisted that "there exists no fatal collision between the words of Scripture and the facts of nature;" on the other hand, he wrote that the Book of Genesis was not meant to be read literally in relation to scientific terms. Against those who said these were in conflict, he wrote "that the contradiction they have imagined can have no real existence, and that whilst the testimony of Moses remains unimpeached, we may also be permitted to confide in the testimony of our senses."

The Ninth Bridgewater Treatise was quoted extensively in Vestiges of the Natural History of Creation. The parallel with Babbage's computing machines is made explicit, as allowing plausibility to the theory that transmutation of species could be pre-programmed.

Plate from the Ninth Bridgewater Treatise, showing a parametric family of algebraic curves acquiring isolated real points

Jonar Ganeri, author of Indian Logic, believes Babbage may have been influenced by Indian thought; one possible route would be through Henry Thomas Colebrooke. Mary Everest Boole argues that Babbage was introduced to Indian thought in the 1820s by her uncle George Everest:

Some time about 1825, [Everest] came to England for two or three years, and made a fast and lifelong friendship with Herschel and with Babbage, who was then quite young. I would ask any fair-minded mathematician to read Babbage's Ninth Bridgewater Treatise and compare it with the works of his contemporaries in England; and then ask himself whence came the peculiar conception of the nature of miracle which underlies Babbage's ideas of Singular Points on Curves (Chap, viii) – from European Theology or Hindu Metaphysic? Oh! how the English clergy of that day hated Babbage's book!

Religious views

Babbage was raised in the Protestant form of the Christian faith, his family having inculcated in him an orthodox form of worship. He explained:

My excellent mother taught me the usual forms of my daily and nightly prayer; and neither in my father nor my mother was there any mixture of bigotry and intolerance on the one hand, nor on the other of that unbecoming and familiar mode of addressing the Almighty which afterwards so much disgusted me in my youthful years.

Rejecting the Athanasian Creed as a "direct contradiction in terms", in his youth he looked to Samuel Clarke's works on religion, of which Being and Attributes of God (1704) exerted a particularly strong influence on him. Later in life, Babbage concluded that "the true value of the Christian religion rested, not on speculative [theology] … but … upon those doctrines of kindness and benevolence which that religion claims and enforces, not merely in favour of man himself but of every creature susceptible of pain or of happiness."

In his autobiography Passages from the Life of a Philosopher (1864), Babbage wrote a whole chapter on the topic of religion, where he identified three sources of divine knowledge:

  1. A priori or mystical experience
  2. From Revelation
  3. From the examination of the works of the Creator

He stated, on the basis of the design argument, that studying the works of nature had been the more appealing evidence, and the one which led him to actively profess the existence of God. Advocating for natural theology, he wrote:

In the works of the Creator ever open to our examination, we possess a firm basis on which to raise the superstructure of an enlightened creed. The more man inquires into the laws which regulate the material universe, the more he is convinced that all its varied forms arise from the action of a few simple principles ... The works of the Creator, ever present to our senses, give a living and perpetual testimony of his power and goodness far surpassing any evidence transmitted through human testimony. The testimony of man becomes fainter at every stage of transmission, whilst each new inquiry into the works of the Almighty gives to us more exalted views of his wisdom, his goodness, and his power.

Like Samuel Vince, Babbage also wrote a defence of the belief in divine miracles. Against objections previously posed by David Hume, Babbage advocated for the belief of divine agency, stating "we must not measure the credibility or incredibility of an event by the narrow sphere of our own experience, nor forget that there is a Divine energy which overrides what we familiarly call the laws of nature." He alluded to the limits of human experience, expressing: "all that we see in a miracle is an effect which is new to our observation, and whose cause is concealed. The cause may be beyond the sphere of our observation, and would be thus beyond the familiar sphere of nature; but this does not make the event a violation of any law of nature. The limits of man's observation lie within very narrow boundaries, and it would be arrogance to suppose that the reach of man's power is to form the limits of the natural world."

Later life

The Illustrated London News (4 November 1871)

The British Association was consciously modelled on the Deutsche Naturforscher-Versammlung, founded in 1822. It rejected romantic science as well as metaphysics, and started to entrench the divisions of science from literature, and professionals from amateurs. Belonging as he did to the "Wattite" faction in the BAAS, represented in particular by James Watt the younger, Babbage identified closely with industrialists. He wanted to go faster in the same directions, and had little time for the more gentlemanly component of its membership. Indeed, he subscribed to a version of conjectural history that placed industrial society as the culmination of human development (and shared this view with Herschel). A clash with Roderick Murchison led in 1838 to his withdrawal from further involvement. At the end of the same year he sent in his resignation as Lucasian professor, walking away also from the Cambridge struggle with Whewell. His interests became more focussed, on computation and metrology, and on international contacts.

Metrology programme

A project announced by Babbage was to tabulate all physical constants (referred to as "constants of nature", a phrase in itself a neologism), and then to compile an encyclopaedic work of numerical information. He was a pioneer in the field of "absolute measurement". His ideas followed on from those of Johann Christian Poggendorff, and were mentioned to Brewster in 1832. There were to be 19 categories of constants, and Ian Hacking sees these as reflecting in part Babbage's "eccentric enthusiasms". Babbage's paper On Tables of the Constants of Nature and Art was reprinted by the Smithsonian Institution in 1856, with an added note that the physical tables of Arnold Henry Guyot "will form a part of the important work proposed in this article".

Exact measurement was also key to the development of machine tools. Here again Babbage is considered a pioneer, with Henry Maudslay, William Sellers, and Joseph Whitworth.

Engineer and inventor

Through the Royal Society Babbage acquired the friendship of the engineer Marc Brunel. It was through Brunel that Babbage knew of Joseph Clement, and so came to encounter the artisans whom he observed in his work on manufactures. Babbage provided an introduction for Isambard Kingdom Brunel in 1830, for a contact with the proposed Bristol & Birmingham Railway. He carried out studies, around 1838, to show the superiority of the broad gauge for railways, used by Brunel's Great Western Railway.

In 1838, Babbage invented the pilot (also called a cow-catcher), the metal frame attached to the front of locomotives that clears the tracks of obstacles; he also constructed a dynamometer car. His eldest son, Benjamin Herschel Babbage, worked as an engineer for Brunel on the railways before emigrating to Australia in the 1850s.

Babbage also invented an ophthalmoscope, which he gave to Thomas Wharton Jones for testing. Jones, however, ignored it. The device only came into use after being independently invented by Hermann von Helmholtz.

Cryptography

Babbage achieved notable results in cryptography, though this was still not known a century after his death. Letter frequency was category 18 of Babbage's tabulation project. Joseph Henry later defended interest in it, in the absence of the facts, as relevant to the management of movable type.

As early as 1845, Babbage had solved a cipher that had been posed as a challenge by his nephew Henry Hollier, and in the process, he made a discovery about ciphers that were based on Vigenère tables. Specifically, he realised that enciphering plain text with a keyword rendered the cipher text subject to modular arithmetic. During the Crimean War of the 1850s, Babbage broke Vigenère's autokey cipher as well as the much weaker cipher that is called Vigenère cipher today. His discovery was kept a military secret, and was not published. Credit for the result was instead given to Friedrich Kasiski, a Prussian infantry officer, who made the same discovery some years later. However, in 1854, Babbage published the solution of a Vigenère cipher, which had been published previously in the Journal of the Society of Arts. In 1855, Babbage also published a short letter, "Cypher Writing", in the same journal. Nevertheless, his priority was not established until 1985.

Babbage involved himself in well-publicised but unpopular campaigns against public nuisances. He once counted all the broken panes of glass of a factory, publishing in 1857 a "Table of the Relative Frequency of the Causes of Breakage of Plate Glass Windows": Of 464 broken panes, 14 were caused by "drunken men, women or boys".

Babbage's distaste for commoners (the Mob) included writing "Observations of Street Nuisances" in 1864, as well as tallying up 165 "nuisances" over a period of 80 days. He especially hated street music, and in particular the music of organ grinders, against whom he railed in various venues. The following quotation is typical:

It is difficult to estimate the misery inflicted upon thousands of persons, and the absolute pecuniary penalty imposed upon multitudes of intellectual workers by the loss of their time, destroyed by organ-grinders and other similar nuisances.

Babbage was not alone in his campaign. A convert to the cause was the MP Michael Thomas Bass.

In the 1860s, Babbage also took up the anti-hoop-rolling campaign. He blamed hoop-rolling boys for driving their iron hoops under horses' legs, with the result that the rider is thrown and very often the horse breaks a leg. Babbage achieved a certain notoriety in this matter, being denounced in debate in Commons in 1864 for "commencing a crusade against the popular game of tip-cat and the trundling of hoops."

Computing pioneer

Part of Charles Babbage's Difference Engine (#1), assembled after his death by his son, Henry Prevost Babbage (1824–1918), using parts found in Charles' laboratory. Whipple Museum of the History of Science, Cambridge, England.

Babbage's machines were among the first mechanical computers. That they were not actually completed was largely because of funding problems and clashes of personality, most notably with George Biddell Airy, the Astronomer Royal.

Babbage directed the building of some steam-powered machines that achieved some modest success, suggesting that calculations could be mechanised. For more than ten years he received government funding for his project, which amounted to £17,000, but eventually the Treasury lost confidence in him.

While Babbage's machines were mechanical and unwieldy, their basic architecture was similar to that of a modern computer. The data and program memory were separated, operation was instruction-based, the control unit could make conditional jumps, and the machine had a separate I/O unit.

Background on mathematical tables

In Babbage's time, printed mathematical tables were calculated by human computers; in other words, by hand. They were central to navigation, science and engineering, as well as mathematics. Mistakes were known to occur in transcription as well as calculation.

At Cambridge, Babbage saw the fallibility of this process, and the opportunity of adding mechanisation into its management. His own account of his path towards mechanical computation references a particular occasion:

In 1812 he was sitting in his rooms in the Analytical Society looking at a table of logarithms, which he knew to be full of mistakes, when the idea occurred to him of computing all tabular functions by machinery. The French government had produced several tables by a new method. Three or four of their mathematicians decided how to compute the tables, half a dozen more broke down the operations into simple stages, and the work itself, which was restricted to addition and subtraction, was done by eighty computers who knew only these two arithmetical processes. Here, for the first time, mass production was applied to arithmetic, and Babbage was seized by the idea that the labours of the unskilled computers [people] could be taken over completely by machinery which would be quicker and more reliable.

There was another period, seven years later, when his interest was aroused by the issues around computation of mathematical tables. The French official initiative by Gaspard de Prony, and its problems of implementation, were familiar to him. After the Napoleonic Wars came to a close, scientific contacts were renewed on the level of personal contact: in 1819 Charles Blagden was in Paris looking into the printing of the stalled de Prony project, and lobbying for the support of the Royal Society. In works of the 1820s and 1830s, Babbage referred in detail to de Prony's project.

Difference engine

The Science Museum's Difference Engine No. 2, built from Babbage's design
Portion of Babbage's difference engine

Babbage began in 1822 with what he called the difference engine, made to compute values of polynomial functions. It was created to calculate a series of values automatically. By using the method of finite differences, it was possible to avoid the need for multiplication and division.

For a prototype difference engine, Babbage brought in Joseph Clement to implement the design, in 1823. Clement worked to high standards, but his machine tools were particularly elaborate. Under the standard terms of business of the time, he could charge for their construction, and would also own them. He and Babbage fell out over costs around 1831.

Some parts of the prototype survive in the Museum of the History of Science, Oxford. This prototype evolved into the "first difference engine". It remained unfinished and the finished portion is located at the Science Museum in London. This first difference engine would have been composed of around 25,000 parts, weighed fifteen short tons (13,600 kg), and would have been 8 ft (2.4 m) tall. Although Babbage received ample funding for the project, it was never completed. He later (1847–1849) produced detailed drawings for an improved version,"Difference Engine No. 2", but did not receive funding from the British government. His design was finally constructed in 1989–1991, using his plans and 19th-century manufacturing tolerances. It performed its first calculation at the Science Museum, London, returning results to 31 digits.

Nine years later, in 2000, the Science Museum completed the printer Babbage had designed for the difference engine.

Completed models

The Science Museum has constructed two Difference Engines according to Babbage's plans for the Difference Engine No 2. One is owned by the museum. The other, owned by the technology multimillionaire Nathan Myhrvold, went on exhibition at the Computer History Museum in Mountain View, California on 10 May 2008. The two models that have been constructed are not replicas.

Analytical Engine

Portion of the mill with a printing mechanism of the Analytical Engine, built by Charles Babbage, as displayed at the Science Museum (London)

After the attempt at making the first difference engine fell through, Babbage worked to design a more complex machine called the Analytical Engine. He hired C. G. Jarvis, who had previously worked for Clement as a draughtsman. The Analytical Engine marks the transition from mechanised arithmetic to fully-fledged general purpose computation. It is largely on it that Babbage's standing as computer pioneer rests.

The major innovation was that the Analytical Engine was to be programmed using punched cards: the Engine was intended to use loops of Jacquard's punched cards to control a mechanical calculator, which could use as input the results of preceding computations. The machine was also intended to employ several features subsequently used in modern computers, including sequential control, branching and looping. It would have been the first mechanical device to be, in principle, Turing-complete. The Engine was not a single physical machine, but rather a succession of designs that Babbage tinkered with until his death in 1871.

Part of the Analytical Engine on display, in 1843, left of centre in this engraving of the King George III Museum in King's College, London

Ada Lovelace and Italian followers

Ada Lovelace, who corresponded with Babbage during his development of the Analytical Engine, is credited with developing an algorithm that would enable the Engine to calculate a sequence of Bernoulli numbers. Despite documentary evidence in Lovelace's own handwriting, some scholars dispute to what extent the ideas were Lovelace's own. For this achievement, she is often described as the first computer programmer; though no programming language had yet been invented.

Lovelace also translated and wrote literature supporting the project. Describing the engine's programming by punch cards, she wrote: "We may say most aptly that the Analytical Engine weaves algebraical patterns just as the Jacquard loom weaves flowers and leaves."

Babbage visited Turin in 1840 at the invitation of Giovanni Plana, who had developed in 1831 an analog computing machine that served as a perpetual calendar. Here in 1840 in Turin, Babbage gave the only public explanation and lectures about the Analytical Engine. In 1842 Charles Wheatstone approached Lovelace to translate a paper of Luigi Menabrea, who had taken notes of Babbage's Turin talks; and Babbage asked her to add something of her own. Fortunato Prandi who acted as interpreter in Turin was an Italian exile and follower of Giuseppe Mazzini.

Swedish followers

Per Georg Scheutz wrote about the difference engine in 1830, and experimented in automated computation. After 1834 and Lardner's Edinburgh Review article he set up a project of his own, doubting whether Babbage's initial plan could be carried out. This he pushed through with his son, Edvard Scheutz. Another Swedish engine was that of Martin Wiberg (1860).

Legacy

In 2011, researchers in Britain proposed a multimillion-pound project, "Plan 28", to construct Babbage's Analytical Engine. Since Babbage's plans were continually being refined and were never completed, they intended to engage the public in the project and crowd-source the analysis of what should be built. It would have the equivalent of 675 bytes of memory, and run at a clock speed of about 7 Hz. They hoped to complete it by the 150th anniversary of Babbage's death, in 2021.

Advances in MEMS and nanotechnology have led to recent high-tech experiments in mechanical computation. The benefits suggested include operation in high radiation or high temperature environments. These modern versions of mechanical computation were highlighted in The Economist in its special "end of the millennium" black cover issue in an article entitled "Babbage's Last Laugh".

Due to his association with the town Babbage was chosen in 2007 to appear on the 5 Totnes pound note. An image of Babbage features in the British cultural icons section of the newly designed British passport in 2015.

Family

A granite, horizontal, geometrically elaborate gravestone surrounded by other headstones
Babbage's grave at Kensal Green Cemetery, London, photographed in 2014

On 25 July 1814, Babbage married Georgiana Whitmore, sister of British parliamentarian William Wolryche-Whitmore, at St. Michael's Church in Teignmouth, Devon. The couple lived at Dudmaston Hall, Shropshire (where Babbage engineered the central heating system), before moving to 5 Devonshire Street, London in 1815.

Charles and Georgiana had eight children, but only four – Benjamin Herschel, Georgiana Whitmore, Dugald Bromhead and Henry Prevost – survived childhood. Charles' wife Georgiana died in Worcester on 1 September 1827, the same year as his father, their second son (also named Charles) and their newborn son Alexander.

  • Benjamin Herschel Babbage (1815–1878)
  • Charles Whitmore Babbage (1817–1827)
  • Georgiana Whitmore Babbage (1818 – 26 September 1834)
  • Edward Stewart Babbage (1819–1821)
  • Francis Moore Babbage (1821–????)
  • Dugald Bromhead (Bromheald?) Babbage (1823–1901)
  • (Maj-Gen) Henry Prevost Babbage (1824–1918)
  • Alexander Forbes Babbage (1827–1827)

His youngest surviving son, Henry Prevost Babbage (1824–1918), went on to create six small demonstration pieces for Difference Engine No. 1 based on his father's designs, one of which was sent to Harvard University where it was later discovered by Howard H. Aiken, pioneer of the Harvard Mark I. Henry Prevost's 1910 Analytical Engine Mill, previously on display at Dudmaston Hall, is now on display at the Science Museum.

Death

Charles Babbage's brain is on display at The Science Museum.

Babbage lived and worked for over 40 years at 1 Dorset Street, Marylebone, where he died, at the age of 79, on 18 October 1871; he was buried in London's Kensal Green Cemetery. According to Horsley, Babbage died "of renal inadequacy, secondary to cystitis." He had declined both a knighthood and baronetcy. He also argued against hereditary peerages, favouring life peerages instead.

Autopsy report

In 1983, the autopsy report for Charles Babbage was discovered and later published by his great-great-grandson. A copy of the original is also available. Half of Babbage's brain is preserved at the Hunterian Museum in the Royal College of Surgeons in London. The other half of Babbage's brain is on display in the Science Museum, London.

Memorials

Green plaque in London

There is a black plaque commemorating the 40 years Babbage spent at 1 Dorset Street, London. Locations, institutions and other things named after Babbage include:

In fiction and film

Babbage frequently appears in steampunk works; he has been called an iconic figure of the genre. Other works in which Babbage appears include:

Publications

Account of the repetition of M. Arago's experiments on the magnetism manifested by various substances during the act of rotation, 1825

ATP synthase

From Wikipedia, the free encyclopedia
 
ATP Synthase
Molecular model of ATP synthase determined by X-ray crystallography. Stator is not shown here.

ATP synthase is a protein that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). ATP synthase is a molecular machine. The overall reaction catalyzed by ATP synthase is:

  • ADP + Pi + 2H+out ⇌ ATP + H2O + 2H+in

ATP synthase lies across a cellular membrane and forms an aperture that protons can cross from areas of high concentration to areas of low concentration, imparting energy for the synthesis of ATP. This electrochemical gradient is generated by the electron transport chain and allows cells to store energy in ATP for later use. In prokaryotic cells ATP synthase lies across the plasma membrane, while in eukaryotic cells it lies across the inner mitochondrial membrane. Organisms capable of photosynthesis also have ATP synthase across the thylakoid membrane, which in plants is located in the chloroplast and in cyanobacteria is located in the cytoplasm.

Eukaryotic ATP synthases are F-ATPases, running "in reverse" for an ATPase. This article deals mainly with this type. An F-ATPase consists of two main subunits, FO and F1, which has a rotational motor mechanism allowing for ATP production.

Nomenclature

The F1 fraction derives its name from the term "Fraction 1" and FO (written as a subscript letter "o", not "zero") derives its name from being the binding fraction for oligomycin, a type of naturally derived antibiotic that is able to inhibit the FO unit of ATP synthase. These functional regions consist of different protein subunits — refer to tables. This enzyme is used in synthesis of ATP through aerobic respiration.

Structure and function

Bovine mitochondrial ATP synthase. The FO, F1, axle, and stator regions are color coded magenta, green, orange, and cyan respectively.
Simplified model of FOF1-ATPase alias ATP synthase of E. coli. Subunits of the enzyme are labeled accordingly.
Rotation engine of ATP synthase.

Located within the thylakoid membrane and the inner mitochondrial membrane, ATP synthase consists of two regions FO and F1. FO causes rotation of F1 and is made of c-ring and subunits a, two b, F6. F1 is made of α, β, γ, and δ subunits. F1 has a water-soluble part that can hydrolyze ATP. FO on the other hand has mainly hydrophobic regions. FO F1 creates a pathway for protons movement across the membrane.

F1 region

The F1 portion of ATP synthase is hydrophilic and responsible for hydrolyzing ATP. The F1 unit protrudes into the mitochondrial matrix space. Subunits α and β make a hexamer with 6 binding sites. Three of them are catalytically inactive and they bind ADP.

Three other subunits catalyze the ATP synthesis. The other F1 subunits γ, δ, and ε are a part of a rotational motor mechanism (rotor/axle). The γ subunit allows β to go through conformational changes (i.e., closed, half open, and open states) that allow for ATP to be bound and released once synthesized. The F1 particle is large and can be seen in the transmission electron microscope by negative staining.[8] These are particles of 9 nm diameter that pepper the inner mitochondrial membrane.

F1 – Subunits
Subunit Human Gene Note
alpha ATP5A1, ATPAF2
beta ATP5B, ATPAF1
gamma ATP5C1
delta ATP5D Mitochondrial "delta" is bacterial/chloroplastic epsilon.
epsilon ATP5E Unique to mitochondria.
OSCP ATP5O Called "delta" in bacterial and chloroplastic versions.

FO region

FO subunit F6 from the peripheral stalk region of ATP synthase.

FO is a water insoluble protein with eight subunits and a transmembrane ring. The ring has a tetrameric shape with a helix-loop-helix protein that goes through conformational changes when protonated and deprotonated, pushing neighboring subunits to rotate, causing the spinning of FO which then also affects conformation of F1, resulting in switching of states of alpha and beta subunits. The FO region of ATP synthase is a proton pore that is embedded in the mitochondrial membrane. It consists of three main subunits, a, b, and c. Six c subunits make up the rotor ring, and subunit b makes up a stalk connecting to F1 OSCP that prevents the αβ hexamer from rotating. Subunit a connects b to the c ring. Humans have six additional subunits, d, e, f, g, F6, and 8 (or A6L). This part of the enzyme is located in the mitochondrial inner membrane and couples proton translocation to the rotation that causes ATP synthesis in the F1 region.

In eukaryotes, mitochondrial FO forms membrane-bending dimers. These dimers self-arrange into long rows at the end of the cristae, possibly the first step of cristae formation. An atomic model for the dimeric yeast FO region was determined by cryo-EM at an overall resolution of 3.6 Å.

FO-Main subunits
Subunit Human Gene
a MT-ATP6
b ATP5F1
c ATP5G1, ATP5G2, ATP5G3

Binding model

Mechanism of ATP synthase. ADP and Pi (pink) shown being combined into ATP (red), while the rotating γ (gamma) subunit in black causes conformational change.
Depiction of ATP synthase using the chemiosmotic proton gradient to power ATP synthesis through oxidative phosphorylation.

In the 1960s through the 1970s, Paul Boyer, a UCLA Professor, developed the binding change, or flip-flop, mechanism theory, which postulated that ATP synthesis is dependent on a conformational change in ATP synthase generated by rotation of the gamma subunit. The research group of John E. Walker, then at the MRC Laboratory of Molecular Biology in Cambridge, crystallized the F1 catalytic-domain of ATP synthase. The structure, at the time the largest asymmetric protein structure known, indicated that Boyer's rotary-catalysis model was, in essence, correct. For elucidating this, Boyer and Walker shared half of the 1997 Nobel Prize in Chemistry.

The crystal structure of the F1 showed alternating alpha and beta subunits (3 of each), arranged like segments of an orange around a rotating asymmetrical gamma subunit. According to the current model of ATP synthesis (known as the alternating catalytic model), the transmembrane potential created by (H+) proton cations supplied by the electron transport chain, drives the (H+) proton cations from the intermembrane space through the membrane via the FO region of ATP synthase. A portion of the FO (the ring of c-subunits) rotates as the protons pass through the membrane. The c-ring is tightly attached to the asymmetric central stalk (consisting primarily of the gamma subunit), causing it to rotate within the alpha3beta3 of F1 causing the 3 catalytic nucleotide binding sites to go through a series of conformational changes that lead to ATP synthesis. The major F1 subunits are prevented from rotating in sympathy with the central stalk rotor by a peripheral stalk that joins the alpha3beta3 to the non-rotating portion of FO. The structure of the intact ATP synthase is currently known at low-resolution from electron cryo-microscopy (cryo-EM) studies of the complex. The cryo-EM model of ATP synthase suggests that the peripheral stalk is a flexible structure that wraps around the complex as it joins F1 to FO. Under the right conditions, the enzyme reaction can also be carried out in reverse, with ATP hydrolysis driving proton pumping across the membrane.

The binding change mechanism involves the active site of a β subunit's cycling between three states. In the "loose" state, ADP and phosphate enter the active site; in the adjacent diagram, this is shown in pink. The enzyme then undergoes a change in shape and forces these molecules together, with the active site in the resulting "tight" state (shown in red) binding the newly produced ATP molecule with very high affinity. Finally, the active site cycles back to the open state (orange), releasing ATP and binding more ADP and phosphate, ready for the next cycle of ATP production.

Physiological role

Like other enzymes, the activity of F1FO ATP synthase is reversible. Large-enough quantities of ATP cause it to create a transmembrane proton gradient, this is used by fermenting bacteria that do not have an electron transport chain, but rather hydrolyze ATP to make a proton gradient, which they use to drive flagella and the transport of nutrients into the cell.

In respiring bacteria under physiological conditions, ATP synthase, in general, runs in the opposite direction, creating ATP while using the proton motive force created by the electron transport chain as a source of energy. The overall process of creating energy in this fashion is termed oxidative phosphorylation. The same process takes place in the mitochondria, where ATP synthase is located in the inner mitochondrial membrane and the F1-part projects into the mitochondrial matrix. By pumping proton cations into the matrix, the ATP-synthase converts ADP into ATP.

Evolution

The evolution of ATP synthase is thought to have been modular whereby two functionally independent subunits became associated and gained new functionality. This association appears to have occurred early in evolutionary history, because essentially the same structure and activity of ATP synthase enzymes are present in all kingdoms of life. The F-ATP synthase displays high functional and mechanistic similarity to the V-ATPase. However, whereas the F-ATP synthase generates ATP by utilising a proton gradient, the V-ATPase generates a proton gradient at the expense of ATP, generating pH values of as low as 1.

The F1 region also shows significant similarity to hexameric DNA helicases (especially the Rho factor), and the entire enzyme region shows some similarity to H+
-powered T3SS or flagellar motor complexes. The α3β3 hexamer of the F1 region shows significant structural similarity to hexameric DNA helicases; both form a ring with 3-fold rotational symmetry with a central pore. Both have roles dependent on the relative rotation of a macromolecule within the pore; the DNA helicases use the helical shape of DNA to drive their motion along the DNA molecule and to detect supercoiling, whereas the α3β3 hexamer uses the conformational changes through the rotation of the γ subunit to drive an enzymatic reaction.

The H+
motor of the FO particle shows great functional similarity to the H+
motors that drive flagella. Both feature a ring of many small alpha-helical proteins that rotate relative to nearby stationary proteins, using a H+
potential gradient as an energy source. This link is tenuous, however, as the overall structure of flagellar motors is far more complex than that of the FO particle and the ring with about 30 rotating proteins is far larger than the 10, 11, or 14 helical proteins in the FO complex. More recent structural data do however show that the ring and the stalk are structurally similar to the F1 particle.

Conformation changes of ATP synthase during synthesis

The modular evolution theory for the origin of ATP synthase suggests that two subunits with independent function, a DNA helicase with ATPase activity and a H+
motor, were able to bind, and the rotation of the motor drove the ATPase activity of the helicase in reverse. This complex then evolved greater efficiency and eventually developed into today's intricate ATP synthases. Alternatively, the DNA helicase/H+
motor complex may have had H+
pump activity with the ATPase activity of the helicase driving the H+
motor in reverse. This may have evolved to carry out the reverse reaction and act as an ATP synthase.

Inhibitors

A variety of natural and synthetic inhibitors of ATP synthase have been discovered. These have been used to probe the structure and mechanism of ATP synthase. Some may be of therapeutic use. There are several classes of ATP synthase inhibitors, including peptide inhibitors, polyphenolic phytochemicals, polyketides, organotin compounds, polyenic α-pyrone derivatives, cationic inhibitors, substrate analogs, amino acid modifiers, and other miscellaneous chemicals. Some of the most commonly used ATP synthase inhibitors are oligomycin and DCCD.

In different organisms

Bacteria

E. coli ATP synthase is the simplest known form of ATP synthase, with 8 different subunit types.

Bacterial F-ATPases can occasionally operate in reverse, turning them into an ATPase. Some bacteria have no F-ATPase, using an A/V-type ATPase bidirectionally.

Yeast

Yeast ATP synthase is one of the best-studied eukaryotic ATP synthases; and five F1, eight FO subunits, and seven associated proteins have been identified. Most of these proteins have homologues in other eukaryotes.

Plant

In plants, ATP synthase is also present in chloroplasts (CF1FO-ATP synthase). The enzyme is integrated into thylakoid membrane; the CF1-part sticks into stroma, where dark reactions of photosynthesis (also called the light-independent reactions or the Calvin cycle) and ATP synthesis take place. The overall structure and the catalytic mechanism of the chloroplast ATP synthase are almost the same as those of the bacterial enzyme. However, in chloroplasts, the proton motive force is generated not by respiratory electron transport chain but by primary photosynthetic proteins. The synthase has a 40-aa insert in the gamma-subunit to inhibit wasteful activity when dark.

Mammal

The ATP synthase isolated from bovine (Bos taurus) heart mitochondria is, in terms of biochemistry and structure, the best-characterized ATP synthase. Beef heart is used as a source for the enzyme because of the high concentration of mitochondria in cardiac muscle. Their genes have close homology to human ATP synthases.[32][33][34]

Human genes that encode components of ATP synthases:

Other eukaryotes

Eukaryotes belonging to some divergent lineages have very special organizations of the ATP synthase. A euglenozoa ATP synthase forms a dimer with a boomerang-shaped F1 head like other mitochondrial ATP synthases, but the FO subcomplex has many unique subunits. It uses cardiolipin. The inhibitory IF1 also binds differently, in a way shared with trypanosomatida.[35]

Archaea

Archaea do not generally have an F-ATPase. Instead, they synthesize ATP using the A-ATPase/synthase, a rotary machine structurally similar to the V-ATPase but mainly functioning as an ATP synthase.[26] Like the bacteria F-ATPase, it is believed to also function as an ATPase.[9]

LUCA and earlier

F-ATPase gene linkage and gene order are widely conserved across ancient prokaryote lineages, implying that this system already existed at a date before the last universal common ancestor, the LUCA.

 

Sunday, August 20, 2023

Plant-based diet

From Wikipedia, the free encyclopedia
Food from plants

A plant-based diet is a diet consisting mostly or entirely of plant-based foods. Plant-based diets encompass a wide range of dietary patterns that contain low amounts of animal products and high amounts of plant products such as vegetables, fruits, whole grains, legumes, nuts and seeds. They do not need to be vegan or vegetarian but are defined in terms of low frequency of animal food consumption.

Terminology

Origin of the term "plant-based diet" is attributed to Cornell University nutritional biochemist T. Colin Campbell who presented his diet research at the US National Institutes of Health in 1980. Campbell's research about a plant-based diet extended from The China Project, a decade-long study of dietary practices in rural China, giving evidence that a diet low in animal protein and fat, and high in plant foods, could reduce the incidence of several diseases. In 2005, Campbell and his son published The China Study, a best-selling book emphasizing the potential health benefits of a plant-based diet.Campbell also used the plant-based concept to educate consumers about how eating meat had significant environmental consequences.

Some authors draw a distinction between diets that are "plant-based" or "plant-only". A plant-based diet may be defined as consuming plant-sourced foods that are minimally processed.

A review analyzing the use of the term plant-based diet in medical literature found that 50% of clinical trials use the term interchangeably with vegan, meaning that the interventional diet did not include foods of animal origin. 30% of studies included dairy products and 20% meat.

In 2021, the World Health Organization (WHO) stated that "plant-based diets constitute a diverse range of dietary patterns that emphasize foods derived from plant sources coupled with lower consumption or exclusion of animal products. Vegetarian diets form a subset of plant-based diets, which may exclude the consumption of some or all forms of animal foods." The WHO lists flexitarian, lacto-vegetarian, lacto-ovo vegetarian, ovo-vegetarian, pescatarian and vegan diets as plant-based.

A 2023 review paper defined plant-based as "a dietary pattern in which foods of animal origin are totally or mostly excluded".

Motivation and prevalence

As of the early 21st century, some 4 billion people are estimated to live primarily on a plant-based diet, some by choice and some because of limits caused by shortages of crops, fresh water, and energy resources. Main motivations to follow a plant-based diet appear to be health aspirations, taste, animal welfare, environmental concern, and weight loss.

Health research

Plant-based diets are of interest in preventing and managing chronic diseases. The British Dietetic Association have stated that a plant-based diet "can support healthy living at every age and life stage", but as with any diet it should be properly planned.

Diet quality

Not all plant-based foods are equally healthy. Rather, plant-based diets including whole grains as the main form of carbohydrate, unsaturated fats as the main form of dietary fat, an abundance of fruit and vegetables, and adequate n-3 fatty acids can be considered healthy.

With processed plant-based foods, such as vegan burger patties or chicken nuggets, becoming more available, there is also concern that plant-based diets incorporating these foods may become less healthy.

In practice lacto-ovo vegetarians or vegans seem to have a higher overall diet quality compared with nonvegetarians. The reason for this is the closer adherence to health organisation recommendations on consumption of fruits, whole grains, seafood and plant protein and sodium. The higher diet quality in vegetarians and vegans may explain some of the positive health outcomes compared with nonvegetarians.

Weight

Observational studies show that vegetarian diets are lower in energy intake than non-vegetarian diets and that, on average, vegetarians have a lower body mass index than non-vegetarians.

Two reviews of preliminary research found that vegetarian diets practiced over 18 weeks or longer reduced body weight in the range of 2–3 kilograms (4.4–6.6 lb), with vegan diets used for 12 weeks or longer reducing body weight by 4 kg.

In obese people, a 2022 review found that plant-based diets improved weight control, LDL and total cholesterol, blood pressure, insulin resistance, and fasting glucose.

Diabetes

Some reviews indicate that plant-based diets including fruits, vegetables, whole grains, legumes, and nuts are associated with a lower risk of diabetes.

Therefor vegetarian and vegan diets are under clinical research to identify potential effects on type 2 diabetes, with preliminary results showing improvements in body weight and biomarkers of metabolic syndrome.

When the focus was whole foods, an improvement of diabetes biomarkers occurred, including reduced obesity. In diabetic people, plant-based diets were also associated with improved emotional and physical well-being, relief of depression, higher quality of life, and better general health.

The American College of Lifestyle Medicine stated that diet can achieve remission in many adults with type 2 diabetes when used as a primary intervention of whole, plant-based foods with minimal consumption of meat and other animal products. There remains a need for more randomized controlled trials "to assess sustainable plant-based dietary interventions with whole or minimally processed foods, as a primary means of treating diabetes with the goal of remission."

Cancer

Plant-based diets are associated with a decreased risk of colorectal and prostate cancer. Vegetarian diets are associated with a lower incidence from total cancer (-8%). A vegan diet seems to reduced risk of incidence from total cancer by -15%. However, there was no improvement in cancer mortality.

Microbiome

Preliminary studies indicate that a plant-based diet may improve the gut microbiome.

Cardiovascular diseases

Prospective cohort studies show that vegetarian diets are associated with reduced risk of CVD and Ischemic Heart Disease, but not stroke. For vegan diets only a reduced risk in IHD was found.

Clinical trials show that plant-based diets, including vegan and vegetarian diets, may lower blood pressure, and blood cholesterol levels.

People on a long-term vegan diet show improvements in cardiometabolic risk factors. Clinical trials also show that the changes in blood pressure associated with a vegan diet without caloric restrictions are comparable to those of dietary practices recommended by medical societies and use of portion-controlled diets.

Bone health

The effect of plant-based diets on bone health is inconclusive. Preliminary research indicates that consuming a plant-based diet may be associated with lower bone density, a risk factor for fractures.

Inflammation

Plant-based diets are under study for their potential to reduce inflammation. C-reactive protein – a biomarker for inflammation – may be reduced by consuming a plant-based diet, particularly in obese people.

Mortality

A 2020 review stated that dietary patterns based on consuming vegetables, fruits, legumes, nuts, whole grains, unsaturated vegetable oils, fish, lean meat or poultry, and are low in processed meat, high-fat dairy and refined carbohydrates or sweets, are associated with a decreased risk of all-cause mortality.

Sustainability

Biomass of mammals on Earth

  Livestock, mostly cattle and pigs (60%)
  Humans (36%)
  Wild mammals (4%)

There is scientific consensus that plant-based diets offer lower greenhouse gas emissions, land use and biodiversity loss. In addition, dietary patterns that reduce diet-related mortality also promote environmental sustainablity.

As a significant percentage of crops around the world are used to feed livestock rather than humans, eating less animal products helps to limit climate change (such as through low-carbon diets) and biodiversity loss. Especially beef, lamb and cheese have a very high carbon footprint. While soy cultivation is a "major driver of deforestation in the Amazon basin", the vast majority of soy crops are used for livestock consumption rather than human consumption. Adopting plant-based diets could also reduce the number of animals raised and killed for food on factory farms.

European respondents to a climate survey conducted in 2021–2022 by the European Investment Bank say that most people will switch to a plant-based diet within 20 years to help the environment

Research from 2019 on six diets found the plant-based diets more environmentally friendly than the diets higher in animal-sourced foods. Of the six mutually-exclusive diets; individuals eating vegan, vegetarian and pescetarian diets had lower dietary-carbon footprints than typical omnivorous diets, while those who ate 'paleolithic' and ketogenic diets had higher dietary-carbon emissions due to their animal sourced foods.

A 2020 study found that the climate change mitigation effects of shifting worldwide food production and consumption to plant-based diets, which are mainly composed of foods that require only a small fraction of the land and CO2 emissions required for meat and dairy, could offset CO2 emissions equal to those of past 9 to 16 years of fossil fuel emissions in nations that they grouped into 4 types. The researchers also provided a map of approximate regional opportunities.

According to a 2021 Chatham House report, supported by the United Nations Environment Programme, a shift to "predominantly plant-based diets" will be needed to reduce biodiversity loss and human impact on the environment. The report said that livestock has the largest environmental impact, with some 80% of all global farmland used to rear cattle, sheep and other animals used by humans for food. Moving towards plant-based diets would free up the land to allow for the restoration of ecosystems and the flourishing of biodiversity.

A 2022 study published in Nature Food found that if high-income nations switched to a plant-based diet, vast swaths of land used for animal agriculture could be allowed to return to their natural state, which in turn has the potential to pull 100 billion tons of CO2 out of the atmosphere by the end of the century. Around 35% of all habitable land around the world is used to rear animals used by humans in food production.

A 2023 study published in Nature Food found that a vegan diet vastly decreases the impact on the environment from food production, such as reducing emissions, water pollution and land use by 75%, reducing the destruction of wildlife by 66% and the usage of water by 54%.

Politics

A reduction in meat consumption and a shift to more plant-based diets is needed to reach climate targets, addressing public health problems, and protecting animal welfare. Research has been done on how to best promote such a change in consumer behaviour.

Some public health organisations advocate a plant-based diet due to its low ecological footprint. These include the Swedish Food Agency in its dietary guideline and a group of Lancet researchers who propose a planetary health diet. Vegan climate activist Greta Thunberg also called for more plant-based food production and consumption worldwide. A 2022 report by the Stockholm Environment Institute and the Council On Energy, Environment and Water included protecting animal welfare and adopting plant based diets on a list of recommendations to help mitigate the ecological and social crises bringing the world to a "boiling point".

Insect cognition

From Wikipedia, the free encyclopedia
A neuron (green and white) in an insect brain (blue)

Insect cognition describes the mental capacities and study of those capacities in insects. The field developed from comparative psychology where early studies focused more on animal behavior. Researchers have examined insect cognition in bees, fruit flies, and wasps.

Research questions consist of experiments aimed to evaluate insects abilities such as perception, emotions attention, memory (wasp multiple nest), spatial cognition, tools use, problem solving, and concepts. Unlike in animal behavior the concept of group cognition plays a big part in insect studies. It is hypothesized some insect classes like ants and bees think with a group cognition to function within their societies; more recent studies show that individual cognition exists and plays a role in overall group cognitive task.

Insect cognition experiments have been more prevalent in the past decade than prior. It is logical for the understanding of cognitive capacities as adaptations to differing ecological niches under the Cognitive faculty by species when analyzing behaviors, this means viewing behaviors as adaptations to an individual's environment and not weighing them more advanced when compared to other different individuals.

Insect foraging cognition

Insects foraging on a yellow flower

Insects inhabit many diverse and complex environments within which they must find food. Cognition shapes how an insect comes to find its food. The particular cognitive abilities used by insects in finding food has been the focus of much scientific inquiry. The social insects are often study subjects and much has been discovered about the intelligence of insects by investigating the abilities of bee species. Fruit flies are also common study subjects.

Learning and memory

Learning biases

Through learning, insects can increase their foraging efficiency, decreasing the time spent searching for food which allows for more time and energy to invest in other fitness related activities, such as searching for mates. Depending on the ecology of the insect certain cues may be used to learn to quickly identify food sources. Over evolutionary time insects may develop evolved learning biases that reflect the food source they feed on.

Biases in learning allow insects to quickly associate relevant features of the environment that are related to food. For example, bees have an unlearned preference for radiating and symmetric patterns — features of natural flowers bees forage on. Bees that have no foraging experience tend to have an unlearned preference for the colours that an experienced forager would learn faster. These colours tend to be those of highly rewarding flowers in that particular environment.

Time-place learning

In addition to more typical cues like color and odor, insects are able to use time as a foraging cue. Time is a particularly important cue for pollinators. Pollinators forage on flowers which tend to vary predictably in time and space, depending on the flower species, pollinators can learn the timing of blooming of flower species to develop more efficient foraging routes. Bees learn at which times and in which areas sites are rewarding and change their preference for particular sites based on the time of day.

These time-based preferences have been shown to be tied to a circadian clock in some insects. In the absence of external cues honeybees will still show a shift in preference for a reward depending on time strongly implicating an internal time-keeping mechanism, i.e. the circadian clock, in modulating the learned preference.

Moreover, not only can bees remember when a particular site is rewarding but they can also remember at what times multiple different sites are profitable. Certain butterfly species also show evidence for time-place learning due to their trap-line foraging behaviour. This is when an animal consistently visits the same foraging sites in a sequential manner across multiple days and is thought to be suggestive of a time-place learning ability.

Innovation capacity

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A bumblebee with experience in the string-pulling task pulls the string to reach an artificial blue flower filled with sugar solution

Insects are also capable of behavioral innovations. Innovation is defined as the creation of a new or modified learned behavior not previously found in the population. Innovative abilities can be experimentally studied in insects through the use of problem solving tasks. When presented with a string-pulling task, many bumblebees cannot solve the task, but a few can innovate the solution.

Those that initially could not solve the task can learn to solve it by observing an innovator bee solving the task. These learned behaviors can then spread culturally through bee populations. More recent studies in insects have begun to look at what traits (e.g. exploratory tendency) predict the propensity for an individual insect to be an innovator.

Social aspects of insect foraging

Social learning of foraging sites

Insects can learn about foraging sites through observation or interaction with other individuals, termed social learning. This has been demonstrated in bumblebees. Bumblebees become attracted to rewarding flowers more quickly if they are occupied by other bumblebees and more quickly learn to associate that flower species with reward. Seeing a conspecific on a flower enhances preferences for flowers of that type. Additionally, bumblebees will rely more on social cues when a task is difficult compared to when a task is simple.

Ants will show conspecifics food sites they have discovered in a process called tandem running. This is considered to be a rare instance of teaching, a specialized form of social learning, in the animal kingdom. Teaching involves consistent interactions between a tutor and a pupil and the tutor typically incurs some sort of cost in order to transmit the relevant information to the pupil. In the case of tandem running the ant is temporarily decreasing its own foraging efficiency in order to demonstrate to the pupil the location of a foraging site.

Evidence for Cumulative culture

Studies in bumblebees have provided evidence that some insects show the beginnings of cumulative culture through the act of refining existing behaviours into more efficient forms. Bumblebees are able to improve upon a task where they must pull a ball to a particular location, a previously socially learned behaviour, by using a more optimal route compared to the route that their demonstrator used. This demonstration of refinement of a previously observed existing behaviour could be considered a rudimentary form of cumulative culture, although this a highly controversial idea. It is important to say that true cumulative culture has been difficult to show in insects and indeed, in all species. This would require culture accumulating over generations to the point where no single individual could independently generate the entire behaviour.

Neural basis of insect foraging

Role of mushroom bodies

A diagram of a fruit fly mushroom body

One important and highly studied brain region involved in insect foraging are the mushroom bodies, a structure implicated in insect learning and memory abilities. The mushroom body consists of two large stalks called peduncles which have cup-shaped projections on their ends called calyces. The role of the mushroom bodies is in sensory integration and associative learning. They allow the insect to pair sensory information and reward.

Experiments where the function of the mushroom bodies are impaired through ablation find that organisms are behaviourally normal but have impaired learning. Flies with impaired mushroom bodies cannot form an odour association and cockroaches with impaired mushroom bodies cannot make use of spatial information to form memories about locations. Electrophysiological underpinnings of the cognition in different parts of the insect brain can be studied by various techniques including in vivo recordings from these parts of the insect brain.

Mushroom body plasticity

Mushroom bodies can change in size throughout the lifespan of an insect. There is evidence these changes are related to the onset of foraging as well as the experience of foraging. In some Hymenoptera mushroom bodies increase in size when nurses become foragers and begin to forage for the colony.

Young bees begin as nurses tending to the feeding and sanitation of the hive’s larvae. As a bee ages it undergoes a shift in tasks from nurse to forager, leaving the hive to collect pollen. This shift in job leads to changes in gene expression within the brain which are associated with an increase in mushroom body size.

Some butterflies have also been shown to undergo an experience-dependent increase in mushroom body size. The period of greatest increase in brain size typically is associated with a period of learning through experiences with foraging demonstrating the importance of this structure in insect foraging cognition.

Mushroom body evolution

Multiple insect taxa have independently evolved larger mushroom bodies. The spatial cognition demands of foraging has been implicated in cases where more sophisticated mushroom bodies have evolved. Cockroaches and bees, which are in different orders, both forage over a large area and make use of spatial information to return to foraging sites and central places which likely explains their larger mushroom bodies. Contrast this with a dipteran such as the fruit fly Drosophila melanogaster, which has relatively small mushroom bodies and less complex spatial learning demands.

Introduction to entropy

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