Although many human characters, in comparison to a chimpanzee, are neotenous, head growth is not. In the fetus of both species, brain and head growth start at approximately the same developmental stage and pro-gress at the same rate
Soon after birth, chimpanzee brain and head growth stops. Human brain and head growth continues for sever-al years after birth. Thus, relative to head growth, reproduction is occurring at a later stage. Assuming that chimpanzees represent the ancestral condition, explain what type of heterochrony humans have in brain de-velopment.
What will be an ideal response?
ANS:
Humans are demonstrating hypermorphosis, in that development is continuing beyond the ancestral point. The appearance of reproductive traits is thus retarded as in recapitulation via hypermorphosis.
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