Editing Evolutionary neuroscience (section)

== History ==
Studies of the brain began during ancient Egyptian times but studies in the field of evolutionary neuroscience began after the publication of Darwin's [[On the Origin of Species]] in 1859. At that time, brain evolution was largely viewed at the time in relation to the incorrect [[scala naturae]]. Phylogeny and the evolution of the brain were still viewed as linear. During the early 20th century, there were several prevailing theories about evolution. [[Darwinism]] was based on the principles of natural selection and variation, [[Lamarckism]] was based on the passing down of acquired traits, [[Orthogenesis]] was based on the assumption that tendency towards perfection steers evolution, and [[Saltation (biology)|Saltationism]] argued that discontinuous variation creates new species. Darwin's became the most accepted and allowed for people to starting thinking about the way animals and their brains evolve.<ref name=Northcutt-2001><br/>{{cite journal |last=Northcutt |first=R.G. |author-link=Glenn Northcutt |date=August 2001 |title=Changing views of brain evolution |journal=[[Brain Research Bulletin]] |volume=55 |issue=6 |pages=663–674 |doi=10.1016/S0361-9230(01)00560-3 |issn=0361-9230 |pmid=11595351 |s2cid=39709902 |lang=en }}</ref>

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 [[Modern synthesis (20th century)|Evolutionary Synthesis]], the study of comparative neuroanatomy was conducted with an evolutionary view, and modern studies incorporate developmental genetics.<ref name=Northcutt-2001/><ref>{{cite book |last=Striedter |first=G.F. |author-link=Georg F. Striedter |year=2009 |chapter=History of ideas on brain evolution |editor-first=Jon H. |editor-last=Kaas |editor-link=Jon Kaas |title=Evolutionary Neuroscience |publisher=Academic Press |isbn=978-0-12-375080-8 |chapter-url=https://books.google.com/books?id=dTEtZTg_fi4C&pg=PA3 |via=Google }}</ref> It is now accepted that phylogenetic changes occur independently between species over time and can not be linear. It is also believed that an increase with brain size correlates with an increase in neural centers and behavior complexity.<ref name=Northcutt-2001/>

=== Major arguments ===
Over time, there are several arguments that would come to define the history of evolutionary neuroscience. The first is the argument between [[Étienne Geoffroy Saint-Hilaire|E.G. St.&nbsp;Hilaire]] and [[Georges Cuvier|G. Cuvier]] over the topic of "common plan versus diversity".<ref name=Kaas-2007/> St.&nbsp;Hilaire argued that all animals are built based on a single plan or [[archetype]] and he stressed the importance of [[Homology (biology)|homologies]] between organisms, while Cuvier believed that the structure of organs was determined by their function and that knowledge of the function of one organ could help discover the functions of other organs.<ref name=Kaas-2007/><ref name=Northcutt-2001/> He argued that there were at least four different archetypes. After Darwin, the idea of evolution was more accepted and St.&nbsp;Hilaire's idea of homologous structures was more accepted. The second major argument is that of Aristotle's [[Aristotle's biology|''scala naturae'']] (scale of nature) and the [[great chain of being]] versus the phylogenetic bush. The ''scala naturae'', later also called the phylogenetic scale, was based on the premise that phylogenies are linear or like a scale while the phylogenetic bush argument was based on the idea that phylogenies were not linear, and more resembled a bush – the currently accepted view. A third major argument dealt with the size of the brain and whether relative size or absolute size was more relevant in determining function. In the late 18th&nbsp;century, it was determined that brain to body ratio reduces as body size increases. However more recently, there is more focus on absolute [[brain size]] as this scales with internal structures and functions, with the degree of structural complexity, and with the amount of [[white matter]] in the brain, all suggesting that absolute size is much better predictor of brain function. Finally, a fourth argument is that of natural selection ([[Darwinism]]) versus developmental constraints (concerted evolution). It is now accepted that the evolution of development is what causes adult species to show differences and evolutionary neuroscientists maintain that many aspects of brain function and structure are conserved across species.<ref name=Kaas-2007/>

=== Techniques ===
Throughout history, we see how evolutionary neuroscience has been dependent on developments in biological theory and techniques.<ref name=Northcutt-2001/> The field of evolutionary neuroscience has been shaped by the development of new techniques that allow for the discovery and examination of parts of the nervous system. In 1873, [[Camillo Golgi|C. Golgi]] devised the silver nitrate method which allowed for the description of the brain at the cellular level as opposed to simply the gross level. [[Santiago Ramón y Cajal|Santiago]] and Pedro Ramon used this method to analyze numerous parts of brains, broadening the field of comparative neuroanatomy. In the second half of the 19th century, new techniques allowed scientists to identify neuronal cell groups and fiber bundles in brains. In 1885, [[Vittorio Marchi]] discovered a staining technique that let scientists see induced axonal degeneration in myelinated axons, in 1950, the "original ''nauta'' procedure" allowed for more accurate identification of degenerating fibers, and in the 1970s, there were several discoveries of multiple molecular tracers which would be used for experiments even today. In the last 20&nbsp;years, [[cladistics]] has also become a useful tool for looking at variation in the brain.<ref name=Northcutt-2001/>