Measuring living primates' teeth can reveal clues to behavior of early human ancestors

Washington, June 27 : A new research is measuring and testing the teeth of living primates to find clues to the behavior of the earliest human ancestors, based on their fossilized remains.

The research, funded by the National Science Foundation and led by University of Arkansas anthropologist Michael Plavcan, will take scientists one step closer to understanding the relationship between canine teeth, body size and the lives of primates.

Plavcan and colleague Christopher B. Ruff of Johns Hopkins School of Medicine report on an initial examination of the function of the shape of canine teeth in primates.

Understanding more about the function of canine teeth can lead to new models for understanding human evolution.

The researchers compared the size, shape and strength of canine teeth from 144 primates with similar measurements taken from 45 carnivores.

They examined the relationship of the size of primates' canines to body size and the relative strength of the teeth.

"The reason we wanted to use the carnivores is that we know carnivores use their canines for killing," said Plavcan. "If primates' canines are too weak to function as weapons, then they're all just for show," he added.

Among anthropoid primates, it is well known that the canine teeth of males are up to four times as long as those of females.

The researchers compared the canine teeth of male and female primates.

"If the male's canines are stronger than the female's canines, that would imply there is sexual selection for strength and that the tooth is actually used as a weapon," said Plavcan.

"Female's canines are short, and shorter, stubbier objects are harder to break. So, if the long, thin male canines are as strong or stronger than those of the female, that would also suggest they are capable of being used for fighting," he added.

"We found that the primate canines are generally as strong as or stronger than carnivore canines," said Plavcan. "But they are not associated with any sort of estimate of sexual selection," he added.

The difference in body size between male and female hominids has been the subject of study because it is an obvious and important trait.

A change in body size can impact many other aspects of life, including metabolism, feeding patterns and vulnerability to predators. Canine teeth, on the other hand, are a far simpler system.

"With canines, we can go in and effectively construct an experiment that allows us to control for all these other variables and look at only one thing," said Plavcan.

"The same phenomenon that works on the canines, we can translate into the body mass and then into behavioral models for the fossil record," he added.

ANI