(April 9, 2012 at 7:09 am)Mosrhun Wrote: We share a common ancestor with modern apes... not lizards.
Technically, we shared a common ancestor with lizards also. That common ancestor lived about 320 million years. Of course we share a much more recent common ancestor with apes, possibly as recent as 6 million years ago.
As to when we lost our fur, and when we pushed into areas that required us to kill furred animals and don their skin, we actually know a great deal from DNA evidence. Not human DNA, but louse DNA.
Louse (the small, itch, icky kind, not the fat religious conservative kind) are very particular to the species they infest. Typically one species of louse infest one species of animals. We filthy unhygenic humans are somewhat unusual in that we are commonly host to to not one, but 3 different spieces of lice. One type of lice live in our head hair (Pediculus humans capitis), and another in our crotch hair (Pthirus pubis), and a third live in our clothing (Pediculus humans corporis). The body louse and head louse are similar, where as the head louse and crotch louse are noticeably different.
Interestingly, crotch lice are similar to a different type of louse that commonly live on chimps. But DNA evidence suggests crotch louse and head louse diverged and became separate speices about 800,000 years ago. This suggests that prior to about a million years ago, humans played host to only one species of louse, which we inherited from our ape ancestors and which coevolved with us. The fact that our ancestors prior to a million years hated only a single louse species suggests louse were free to travel all over our bodies and intermingle. This suggests as recently as a million years ago, long after the last Australopithecus dies out, our immediate ancestors still had quite a bit of hair all over their bodies to allow a louse to travel from head to foot.
Appearently sometime around 800,000 years ago, our ancestors had begun to acquire the unique pattern of hair that characterize modern humans - extensive head hair, considerable pubic hair, with very little hair in between. So louse that were in the head could no longer mingle with the ones in the crotch, and two different species of human louse (head louse and crotch louse) evolved.
So where does the their species, the body louse fit in? well body louse are very similar to head louse. Genetic evidence suggests they diverged about 70,000 years ago. Body louse live a life style different from either head or crotch louse. Head and crotch louse must live on the human body. Body louse can live on human clothing. This suggested that humans first started to wear close fitting, furry clothing about 70,000 years ago.
