Researchers from several universities have been working on a study that compares the young adult mortality rate and the rate of aging between eight different primates.

Young adult mortality rates are the rates of death in the younger portion of the population. The rate of aging is the proportion of a population that dies as age increases. Those primates in the study are humans, gorillas, muriquis, blue monkeys, chimpanzees, baboons, sifakas and capuchin monkeys.

According to Susan Alberts, professor of biology at Duke University, the study found that for humans, females were not much different than other species.

“We found that for females, humans are not different than some other primates in terms of their rate of aging or in their young adult mortality rates,” said Anne Bronikowski, associate professor of ecology, evolution and organismal biology at Iowa State.

For males, however, the study showed that human males had a lower young adult mortality rate and a lower rate of aging.

“When we compared male primates among each other, human males actually do have a lower mortality at the beginning of adulthood and a slower increase in mortality across the adult lifespan in comparison to other males,” said Bronikowski.

However, the study also found that muriquis were the only other primates to not follow the normal pattern for males. Bronikowski said muriquis do not have male-male competition for females, which may contribute to the lower young adult rates and rate of aging.

The study indicates that between males and females, there is not much of a difference despite the fact that on average, females live four years longer than males.

Bronikowski said all causes of death for humans were taken into account as the cause of death in primates cannot always be determined. Additionally, the study chose a life table that was meant to give the most difference between humans and primates.

“We chose a life table that we thought would give us a pretty high likelihood of showing differences between humans and wild primates,” Bronikowski said. “The fact that we still found similar patterns for humans in the U.S. was an interesting result.”

The study shows little difference between human males and females when they are compared, despite the fact females live an average of four years longer than males. Overall though, the study shows that females fit the female pattern, while males do not.

“For me what it really highlights is the value of comparative approach. It really helps us understand, what … the landscape looks like,” Bronikowski said.

“Research like this sheds light on how humans fit in a comparative landscape of aging,” Alberts said. “It provides insight into our evolutionary history.”