>Think of it this way: why has evolution designed us to get wisdom
>teeth that won't fit in our mouths (if all the other teeth are still
>there) at 18? Wisdom teeth are big suckers; you have to figure that
>modal human experience during the deep time in which mouth evolution
>takes place had us losing *8* adult teeth by the time we were 20...
Brad, here is some more on teeth by John Maynard Smith; while not speaking to the point here, it is quite interesting:
"A diagnostic feature of mammals is that they posess double rooted molar teeth, but a far more striking feature of their dentition is that the teeth in different parts of the jaws differ in shape and function. For example cats have small incisors, large stabbing canines, and scissor like molars, whereas horses have cropping incisors, no canines, and high ridged grinding molars. In contrast to this variation in the structure of the teeth from species to species, and from one part of the jaws to another in mammals, reptiles tend to have relatively simple teeth whose shape varies little from the front to the back of the jaw. One feature of the development of mammals which may have favoured the evolution of their highly specialzed teeth is that teeth are replaced only once during a lifetime, whereas in reptiles there is continuous tooth replacement throughout life. If teeth are continually falling out and being replaced by others, it is difficult to maintain the accurate fit between the teeth in the upper and lower jaws which is necessary if the specialized teeth of mammals are to work efficiently; for example, the carpassial teeth of carnivorous mammals, like the scissors they resemble, will cut only if there is a proper relationship between the two blades. In other words, a pattern of tooth development common to all mammals has favoured the evolution of enormous variation in detailed structure between them. This example helps to show that, whereas differences between animals may be transmitted in sexual reproduction by differences between chromosomes, these chromosomal differences produce their effects during individual development."
Theory of Evolution. Cambridge, 1993, p. 65-6
rb