g-rh@cca.CCA.COM (Richard Harter) (01/21/88)
Note: I changed the title from the reproductive advantages of rape to one suiting the contents of this article. My apologies for violating net usage. I also removed soc.men and soc.women from the followup list. In article <1413@sugar.UUCP> peter@sugar.UUCP (Peter da Silva) writes: > >There just aren't that many qualitative differences between humans and other >species... most of the differences are in degree rather than kind. This isn't true. It is true that humans are mammals and retain many of the body plan features of mammals. However humans are quite unusual. They have unique characteristics and others that are very rare. Many differences are so marked that they constitute a difference of kind rather than merely degree. Here is a partial list. (1) Upright posture. There are, and have been many bipeds. However all other bipeds keep the spine at right angles to the body and balance the body over the legs. Humans rotate the spine so that it is vertical over the legs. Some animals can assume the upright posture for limited periods of time, but none are built for it. There are a remarkable number of adjustments that have to be made in the skeleton to do this. Upright posture seems to be the key evolutionary innovation in the hominid line. (2) Lack of estrus. In almost all animals the females have an estrus cycle, i.e. they only copulate at certain specific times. [In some species the estral cycle is weak, but this is rare.] Human sexual behaviour has many unusual features. (3) Long life. Interestingly enough, almost all mammals have the same lifespan -- if you count lifespan in heartbeats. Humans are the notable exception; they live four times longer than they ought to, if they fit the general pattern. (4) Big brains. Humans have much bigger brains (particularly cerebral cortex) for their body weight than any other animal. The difference is so marked as to be a difference in kind rather than one in quantity. (5) Complex non-instinctual social behaviour. Again the difference is so large as to be a difference in kind rather one of quantity. (6) A true opposable thumb. I think that this is unique to humans among vertebrates. The Panda does have an opposable "thumb" which is actually an enlarged wrist bone. (7) An advanced tool user. Other animals do use tools upon occasion. However they lack the structural modifications needed for tool using. Again, a difference in kind. (8) Cursorial hunter adaptations. Not unique, but rare. Cursorial hunters kill game by chasing it until it gives up. Example -- a human being (in good condition) can capture a horse by chasing it until it collapses. The horse can run faster, but the human has more endurance. There are a host of modifications needed for this, effecient sweating is an example. Wolves are cursorial hunters. (9) Premature birth. If humans followed the patterns of other mammals human gestation would take about 18 months. Human infants are born semi-foetal. Much of the development that is completed in the womb in other placental mammals is completed after birth in humans. In particular, brain growth is not completed until well after birth. [This is necessary -- if the head finished development the foetus couldn't get out through the birth canal. As it is, it's a tight squeeze; birth in humans is unusually traumatic.] -- In the fields of Hell where the grass grows high Are the graves of dreams allowed to die. Richard Harter, SMDS Inc.