UMass Amherst Anthropologist Investigates Dental Development and Body Size in Primates

AMHERST, Mass. - University of Massachusetts anthropologist Laurie R. Godfrey is a member of a team of researchers that finds a number of species of living and recently extinct lemurs living on Madagascar share very accelerated development of their teeth and can chew leaves and other hard-to-process foods soon after birth. The findings are published in the April 30 issue of the Proceedings of the National Academy of Sciences.

Godfrey, along with Gary Schwartz of George Washington University, and Karen Samonds of Stony Brook University, examined the teeth of an extinct species of large chimpanzee-sized sloth lemurs, Palaeopropithecus, and found that like some existing lemurs, the indris and sifakas, they were born with highly developed teeth. "By weaning, they are, in effect, little chewing machines with mouths full of adult teeth," Godfrey says. "This would have helped them to survive in the precarious and unpredictable environment of Madagascar."

The findings are significant because ape-sized primates – chimpanzees, gorillas, orangutans, and humans – develop their teeth very slowly, Godfrey says. In chimpanzees, the young don’t see molars begin to erupt, or push through the gums, until about age 3, and dental eruption is not complete until age 13. In humans, the first permanent molars erupt at age 6 and it takes until past age 20 for molars to completely erupt, she says. The rapid development of teeth is probably a survival mechanism for the lemurs, Godfrey says, giving them the ability to chew solid food shortly after they are born. The study of the teeth of the extinct Palaeopropithecus was conducted by looking at the microstructure of its teeth to calculate how long it took for the animal’s tooth crowns to form, and how soon before birth tooth crown formation began, she says.

Godfrey has spent nearly three decades investigating fossils in Madagascar and has specialized in studying lemurs. Madagascar is a large island off the east coast of Africa which is believed to have separated from the main continent millions of years ago. Because it was isolated, its animals have evolved on parallel tracks with those in Africa.

Lemurs provide a good example of this isolated development because they are close relatives of species of animals that lived 50 million years ago, but today exist only on Madagascar in the wild, Godfrey says. Lemurs are primitive primates that resemble a cross between monkeys and ferrets and have thrived on Madagascar long after dying out elsewhere because of the island’s lack of competition and predators. Humans came to Madagascar from Africa and Southeast Asia about 2,000 years ago and have put the lemurs in great danger.

Godfrey has taught and conducted research at the University since 1977 and in 1998 received the University’s Distinguished Teaching Award.