Editing Encephalization quotient (section)

==History==
The concept of encephalization has been a key evolutionary trend throughout human evolution, and consequently an important area of study. Over the course of hominin evolution, brain size has seen an overall increase from 400&nbsp;cm<sup>3</sup> to 1400&nbsp;cm<sup>3</sup>.<ref name=pmid16505378/> Furthermore, the genus ''Homo'' is specifically defined by a significant increase in brain size.<ref name=Cairo2011/> The earliest ''Homo'' species were larger in brain size as compared to contemporary ''[[Australopithecus]]'' counterparts, with which they co-inhabited parts of Eastern and Southern Africa.

Throughout modern history, humans have been fascinated by the large relative size of our brains, trying to connect brain sizes to overall levels of intelligence. Early brain studies were focused in the field of phrenology, which was pioneered by [[Franz Joseph Gall]] in 1796 and remained a prevalent discipline throughout the early 19th century.<ref name=Cairo2011/> Specifically, phrenologists paid attention to the external morphology of the skull, trying to relate certain lumps to corresponding aspects of personality. They further measured physical brain size in order to equate larger brain sizes to greater levels of intelligence. Today, however, [[phrenology]] is considered a [[pseudoscience]].<ref>{{cite book |last=Graham |first=Patrick |title=Phrenology: [revealing the mysteries of the mind |year=2001 |publisher=Distributed by American Home Treasures |language=en|isbn=9780779251353 |oclc=51477257}}</ref>

Among ancient Greek philosophers, [[Aristotle]] in particular believed that after the heart, the brain was the second most important organ of the body. He also focused on the size of the human brain, writing in 335&nbsp;BCE that "of all the animals, man has the brain largest in proportion to his size."<ref name="RussellNorvigAI">{{cite book |author1=Russell, Stuart |author2=Norvig, Peter |title=Artificial Intelligence: A modern approach |year=2003 |place=Upper Saddle River, N.J. |publisher=Prentice Hall/Pearson Education |isbn=978-0-13-790395-5}}</ref> In 1861, French neurologist [[Paul Broca]] tried to make a connection between brain size and intelligence.<ref name=Cairo2011/> Through observational studies, he noticed that people working in what he deemed to be more complex fields had larger brains than people working in less complex fields. Also, in 1871, [[Charles Darwin]] wrote in his book ''[[The Descent of Man]]'': "No one, I presume, doubts that the large proportion which the size of man's brain bears to his body, compared to the same proportion in the gorilla or orang, is closely connected with his mental powers."<ref name="Darwin1871reprintp145">{{cite book |author=Darwin, Charles |title=The Descent of Man, and Selection in Relation to Sex |page=[https://archive.org/details/descentofmans00darw/page/145 145] |place=Princeton, New Jersey |publisher=Princeton University Press |isbn=978-0-691-02369-4 |edition=reprint |orig-year=1871 |year=1981 |url=https://archive.org/details/descentofmans00darw|url-access=registration }}</ref>{{refn|See also {{cite web |author=Darwin, Charles |title=The Descent of Man, and Selection in Relation to Sex |year=1874 |edition=reprint |url=https://archive.org/stream/descentofmansele00darwiala#page/60/mode/2up |page=60}} same quote as Darwin (1871)<ref name="Darwin1871reprintp145"/> cited above, on p.&nbsp;60 in online text of earlier reprint of second (1874) edition.}} The concept of quantifying encephalization is also not a recent phenomenon. In 1889, [[Francis Galton|Sir Francis Galton]], through a study on college students, attempted to quantify the relationship between brain size and intelligence.<ref name=Cairo2011/>

Due to the [[Nazi]]'s racial policies before and during [[World War II]], studies on brain size and intelligence temporarily gained a negative reputation, as they resemble the "Ubermensch" school of thought that enable the Holocaust.<ref name=Cairo2011/> However, with the rise of neofascism and the advent of imaging techniques such as the [[Functional magnetic resonance imaging|fMRI]] and [[PET scan]], several scientific studies were launched to suggest a relationship between encephalization and advanced cognitive abilities. Harry J. Jerison, who invented the formula for encephalization quotient, believed that brain size was proportional to the ability of humans to process information.<ref>{{Cite journal|last1=Jerison H. J.|last2=Barlow Horace Basil|last3=Weiskrantz Lawrence|date=13 February 1985|title=Animal intelligence as encephalization|journal= Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences|volume=308|issue=1135|pages=21–35|doi=10.1098/rstb.1985.0007|pmid=2858875|bibcode=1985RSPTB.308...21J|doi-access=free}}</ref> With this belief, a higher level of encephalization equated to a higher ability to process information. A larger brain could mean a number of different things, including a larger cerebral cortex, a greater number of neuronal associations, or a greater number of neurons overall.<ref name=Cairo2011/>