A theory of the origin of cerebral asymmetry: epigenetic variation superimposed on a fixed right-shift.
A theory of the genetic basis of cerebral asymmetry is outlined according to which (1) a single right-shift factor in all human individuals interacts with (2) epigenetic variation that is apparently random, transmissible between parent and child, but with a half-life extending over a small number of generations. The right-shift factor arose late (150 to 200 thousand years ago [KYA]) in hominid evolution as a mutation in the X copy of a gene pair (Protocadherin 11XY) in a region of homology between the X and Y chromosomes created by a duplication 6MYA at the chimpanzee hominid separation. The epigenetic imprint originates in the process now known as "meiotic suppression of unpaired chromosomes" (MSUC); it reflects random pairing of partly homologous X and Y chromosome regions in male meiosis, and confers species-specific diversity of cerebral structure on the human population.
Crow
T J
TJ
Sane POWIC, Warneford Hospital, Oxford, UK. tim.crow@psych.ox.ac.uk
D001921:Brain / Q000502:physiology*; D041321:Chromosomes, Human, X / Q000235:genetics; D041322:Chromosomes, Human, Y / Q000235:genetics; D003071:Cognition / Q000502:physiology; D044127:Epigenesis, Genetic / Q000235:genetics*; D005260:Female; D007839:Functional Laterality / Q000235:genetics*; D006801:Humans; D007206:Individuality; D007802:Language; D008297:Male; D008957:Models, Genetic