HOT FLASH: GORILLAS, TOO, EXPERIENCE MENOPAUSE

No hot flashes, no mood swings, no migraines. This is not your typical menopause. In fact, the only evidence of moodiness is watching her toss hay at her uninterested mate.

This is gorilla menopause - the subject of a national study led by Brookfield Zoo and funded by the U.S. National Institutes of Health (NIH) National Institute on Aging, in hopes of learning more about the human female reproductive cycle.

Its cause is timely. By 2025 there will be an estimated 825 million women over age 65 - the largest-ever population of women simultaneously in menopause. The population of gorillas, which share many physical traits with humans, is mirroring these demographics in U.S. zoos, according to Brookfield Zoo research scientist and primatology specialist Dr. Sylvia Atsalis, who developed the study with Dr. Sue Margulis, former Brookfield Zoo behavioral research manager and now curator of primates at Lincoln Park Zoo. Like humans, gorillas in zoos are living longer than ever because of advances in scientific knowledge, nutrition and health care.

"The NIH was interested in our study because there's a great deal of concern about maintaining the well-being of an aging human population," says Dr. Atsalis. "As primates, humans and gorillas share many important physical traits. Our findings underscore those similarities and the parallel between humans and gorillas, our evolutionary cousins, who may be good models for an improved understanding of menopause."

Mysteries of Menopause
In addition to supplementing our understanding of physiological changes at menopause and how we might help human women and gorillas prevent osteoporosis, heart disease and other maladies linked to the onset of menopause, the gorilla research may help probe the numerous questions surrounding human menopause. Menopause is an issue of fervent and long-standing debate among anthropologists, according to Dr. Atsalis.

Along with humans, gorillas and a handful of other primates, there is only one other species that is known to have a lifespan that continues well past its reproductive years - the short-finned pilot whale. Why? Why have some animals evolved to live past their generative years but not others? What is the biological purpose of menopause? Why is there no equal point for men, at which their reproductive capacity unquestionably ceases?

Theories are rife, including the societal roles that both mothers and grandmothers can play long past their reproductive years, in terms of nurturing healthy offspring. There is also evidence of the valuable, social function of older individuals, as carriers of wisdom gained through experience.

"A zoo is a perfect setting for exploring these questions. Researchers are able to non-invasively extract data from consistent, documented social groups without making special arrangements," says Dr. Atsalis. "All of the major health organizations would like to learn what they can about female aging because they are preparing to serve the health care needs of what will soon be the largest-ever concentration of menopausal women." What's more, she adds, the study's result will better position zoos to provide even more informed care for aging gorillas