CHICAGO — Observed in the wild and tested in captivity, chimpanzees invite comparison with humans, their close relatives. They bear a family resemblance that fascinates people, and scientists see increasing evidence of similarities in chimp behavior and skills, making some of them think on the vagaries of evolution.
For some time, paleontologists and evolutionary biologists have known that chimp ancestors were the last line of today's apes to diverge from the branch that led to humans, probably six million, maybe four million years ago. More recent examination shows that despite profound
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