Editing Optic chiasm (section)

=== Mammals ===

{{Main|Contralateral brain}}
{{See also|Axial twist theory}}

Since all vertebrates, even the earliest fossils<ref name="Janvier1996">{{cite book|title=Early vertebrates|last=Janvier|first=P.|publisher=Clarendon Press, Oxford University Press|year=1996|isbn=978-0198540472|location=New York}}</ref> and modern jawless ones,<ref name="Nieuwenhuys1998" /> possess an optic chiasm, it is not known how it evolved.<ref name="Lussanet2012">{{cite journal|last1=de Lussanet|first1=M.H.E.|last2=Osse|first2=J.W.M.|year=2012|title=An ancestral axial twist explains the contralateral forebain and the optic chiasm in vertebrates|journal=Animal Biology|volume=62|issue=2|pages=193–216|arxiv=1003.1872|doi=10.1163/157075611X617102|s2cid=7399128 }}</ref> A number of theories have been proposed for the function of the optic chiasm in vertebrates (see [[Contralateral brain#Theories|theories]]). According to the [[Axial Twist theory]] the optic chiasm develops as a consequence of a twist in the early [[embryo]].<ref name="lussanet2019">{{cite journal|last=de Lussanet|first=M.H.E.|year=2019|title=Opposite asymmetries of face and trunk and of kissing and hugging, as predicted by the axial twist hypothesis|journal=PeerJ|volume=7|pages=e7096|doi=10.7717/peerj.7096|pmid=31211022|pmc=6557252 |doi-access=free }}</ref>

In [[Siamese (cat)|Siamese cat]]s with certain [[genotypes]] of the [[albino]] gene, the wiring is disrupted, with more of the nerve-crossing than normal.<ref>{{cite journal|vauthors=Schmolesky MT, Wang Y, Creel DJ, Leventhal AG|year=2000|title=Abnormal retinotopic organization of the dorsal lateral geniculate nucleus of the tyrosinase-negative albino cat.|journal=J Comp Neurol|volume=427|issue=2|pages=209–19|doi=10.1002/1096-9861(20001113)427:2<209::aid-cne4>3.0.co;2-3|pmid=11054689|s2cid=32536933 |doi-access=free}}</ref> Since siamese cats, like [[albino]] [[tigers]], also tend to cross their eyes ([[strabismus]]), it has been proposed that this behavior might compensate the abnormal amount of [[decussation]].<ref>{{cite journal|last1=Guillery|first1=RW|last2=Kaas|first2=JH|date=June 1973|title=Genetic abnormality of the visual pathways in a "white" tiger|journal=Science|volume=180|issue=4092|pages=1287–9|bibcode=1973Sci...180.1287G|doi=10.1126/science.180.4092.1287|pmid=4707916|s2cid=28568341 }}</ref><ref>{{cite journal|author=Guillery RW|author-link=Rainer Guillery|date=May 1974|title=Visual pathways in albinos|journal=Sci. Am.|volume=230|issue=5|pages=44–54|bibcode=1974SciAm.230e..44G|doi=10.1038/scientificamerican0574-44|pmid=4822986}}</ref>