New Scientist is carrying this article summarizing a new study on hominid fossils. By doing a survey of dental fossils, a pair of scientists has found evidence of an explosion of people surviving into old age may have been fundamental to the success of our species, and perhaps the failure of other hominids.

The use of teeth is clever, and has a reason. Hominids, up until about fifteen thousand years ago, were quite rare and therefore their fossils are few and far between. Much of the hominid fossil record is only teeth, because teeth are the most likely things to fossilize. In fact, teeth are probably the only hominid fossils common enough over a long enough period of time to make a statistical analysis like this meaningful.

Just goes to show there's no such thing as "old, useless" evidence.