Chimp Study Contradicts Another Chimp Study

Speaking of one recent study possibly contradicting or greatly affecting another, "Chimps mature with human ancestor" (_Science News_ v. 166, 7/31/04, p. 77) may relate to the recent report claiming a study of Neandertal teeth show these people were distinct from our ancestors humans.

This new study "challenges the view that evolution proceeded gradually from a fast-growing chimplike ancestor around 8 million years ago to a slower-growing Homo erectus, which lived from about 1.6 million to 400,000 years ago, and then to an even slower-developing Homo sapiens.

This view had been fostered by studies of captive chimps, but this new study looked at wild chimps and found that "dental growth occurs much more slowly." It appears in the July 20, 2004, Proceedings of the National Academy of Sciences.

I think the real significance of this study is that you can't tell anything about growth rates in the past by studying teeth of living creatures alone. As mentioned in an earlier Comments, a study of hyraxes showed that different diets changed the proportions of their faces.

This study shows that tooth growth (and outgrowing infancy and reaching maturity) can be altered by living conditions. Studies that try to draw major conclusions about extinct organisms based on one or two fossil characteristics and assumptions based on similar organisms living today are stepping out of bounds.

Until Next Time,
David Bump