AMES, Iowa - A recent study debunks the long-held belief in the scientific community that humans have an aging advantage over other primates.
By studying mortality models of human aging along with examining seven wild primate species, researchers have shown that human and non-human primate aging follows similar patterns.
Anne Bronikowski, associate professor of ecology, evolution and organismal biology at Iowa State University, was the demographer for the research team and thinks there are several important findings in the paper, which is published in the current issue of the journal Science.
Life span patterns are most affected by both early adult mortality rates of a species and also how quickly that species increases mortality with advancing adult age.
Humans had been believed to be different from other primates in the measure of how mortality increases with advancing adult age, but this research shows that is not the case.
"First, we found that the thing that makes humans exceptional - that gives them their long life - is that they have both low early adult mortality rate and a low rate of aging," said Bronikowski.
However, some primates in the study aged as slowly as humans, while others had low mortality rates similar to human mortality. So humans were not unique in either measure.
No primates, except for humans, had both. That is what makes us long-lived, she said.
Senescence patterns, or adult aging, can be affected by the environment. The right conditions can make for longer life and these leave their mark on mortality rates.
"Some of these aspects of aging can be molded by local hazards and medical intervention" she added. "Yet, what determines maximum life span for humans remains unknown."
That current maximum life span for humans is 125 years. Life expectancy for Westernized humans is 80-plus years for those who reach puberty, she said. That is an increase from around a 40 to 50-year life expectancy when humans lived as hunters and gatherers.
Since environment and medicine can impact lifespan and aging, the hope is that humans may be able to live healthy lives that are free from the physical deterioration associated with advancing age until close to age of death, Bronikowski said. Comparative studies of different primate species can help us understand where researchers might see evolutionary constraints in aging and where to apply resources for effective treatments.
Bronikowski also noted that females in all species but one lived longer than males. The species that did not have this sex difference in aging and life span, muriqui, is revealing to researchers because it is the only species in the study that does not have a male-male competition for female mates.
The researchers looked at sifaka, northern muriqui, capuchin, yellow baboons, blue monkeys, chimpanzees and gorillas in the study.
As demographer on the project, Bronikowski worked with long-term census data from each primatologist's field study to develop mortality tables and fit models of increasing mortality.
The research results were part of a three-year collaboration through the National Science Foundation's National Evolutionary Synthesis Center and National Center for Ecological Analysis and Synthesis.
Along with Bronikowski, other researchers included Susan Alberts, Anne Pusey and William Morris, all from Duke University, Durham, N.C.; Marina Cords, Columbia University, New York; Jeanne Altmann, Princeton University, N.J.; Dianne Brockman, University of North Carolina, Charlotte; Linda Fedigan, University of Calgary, Canada; Tara Stoinski, The Dian Fossey Gorilla Fund International; and Karen Strier, University of Wisconsin-Madison.