Tooth Development and Weaning in Chimpanzees Not as Closely Related as Once Thought

Jan. 28, 2013 — For more than two decades, scientists have relied on studies that linked juvenile primate tooth development with their weaning as a rough proxy for understanding similar developmental landmarks in the evolution of early humans. New research from Harvard, however, is challenging those conclusions by showing that tooth development and weaning aren't as closely related as previously thought.

Using a first-of-its-kind method, a team of researchers led by professors Tanya Smith and Richard Wrangham and Postdoctoral Fellow Zarin Machanda of Harvard's Department of Human Evolutionary Biology used high-resolution digital photographs of chimps in the wild to show that after the eruption of their first molar tooth, many juvenile chimps continue to nurse as much, if not more, than they had in the past. Their study is described in a January 28 paper in the Proceedings of the National Academy of Sciences.

"When these earlier studies were published about 20 years ago, they found a very tight relationship between the eruption of the first molar and certain developmental milestones, particularly weaning," Smith explained. "A number of researchers have tried to extrapolate that relationship to the human fossil record, but it now appears that our closest living relative doesn't fit that pattern. That suggests we should be more cautious if we want to infer what juvenile hominins were like."

Read more:  http://www.sciencedaily.com/releases/2013/01/130128151926.htm