TEMPE, Ariz. The timing of molar emergence and its relation to growth and reproduction in apes is being reported by two scientists at Arizona State University's Institute of Human Origins in the Dec. 28 online early edition of the Proceedings of the National Academy of Sciences (PNAS).
From the smallest South American monkeys to the largest African apes, the timing of molar development and eruption is closely attuned to many fundamental aspects of a primate's biology, according to Gary Schwartz, a researcher at the Institute of Human Origins and an associate professor in the School of Human Evolution and Social Change in ASU's College of Liberal Arts and Sciences.
"Knowing the age when the first molar appears in the mouths of most primates allows researchers to predict a host of life history attributes, such as gestation length, age at sexual maturity, birth spacing, and overall lifespan. Humans are unique among primates because our life histories are so slow and thus our molars emerge relatively late. Given that apes are our closest living relatives, understanding the broader context of when the characteristic slower development of humans evolved is of great interest," Schwartz explains.
"We've known quite a bit about the timing of molar development in chimpanzees, which is important because they are our closest living relative. However, we've known virtually nothing about when this important event occurs in other wild-living ape species until now," says lead author Jay Kelley, a research affiliate at ASU's Institute of Human Origins and an associate professor in the Department of Oral Biology at the University of Illinois, Chicago.
Because of the difficulties in obtaining tooth emergence ages from animals in the wild, Kelley opted for other means; he searched for specimens in museums. At the Zoologische Staatssammlung in Munich he found skulls of a wild-shot orangutan (Pongo pygmaeus pygmaeus) and gorilla (G
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Arizona State University