muscadine: (Science/Teaching)
[personal profile] muscadine
I learned or was reminded of the following interesting things on Nova's special on "Becoming Human" last night:
* Humans are one of the few animals associated with more than one type of louse. Head lice are endemic human lice but pubic lice are actually evolved from gorilla lice. Draw your own conclusions. ;)
* Bipedalism (and resulting freeing up of hands for tool use) was not enough to spur increases in overall brain size/capacity, although there is some evidence of shifts in the way brain capacity was used. The latest scientific speculation suggests that the Homo genus (with an increased brain capacity, among other distinctive traits) and the Homo sapiens species are probably both the result of extreme climate change. Climate and fossil data suggest the growth of Homo brain capacity was an adaptation towards a cycle of drastic climate changes in Africa alternating between rainforest-like conditions and drought. Homo sapiens are probably the result of an extreme, prolonged drought on the African continent that isolated Homo populations and almost drove them to extinction. Interesting that now we're the cause, rather than the effect.
* However, bipedalism was one thing that allowed human ancestors to leave the forests and compete effectively in the food chain, since bipedalism is a much more energy efficient method of travel over ground. Apparently it takes chimpanzees 4x the energy to walk.
* Hair loss is thought to at least initially be an adaptation related to bipedalism and the evolving ability to do endurance running. Bipedalism plus hair loss allowed efficient travel and the ability to avoid overheating, which allowed humans to compete with other predators by practicing a different, rarely practiced form of hunting (chasing prey to exhaustion) and to be active during the day when most predators are less active.

BTW, the series is available online starting here:
http://www.pbs.org/wgbh/nova/evolution/becoming-human-part-1.html

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