This article By John Allen — Cox News Service

WACO, Texas -A new theory on aging seems to confirm what many of us already knew: Grandmas and grandpas are the best.

The theory, from a researcher at the University of California at Berkeley, proposes that doting grandparents are significant contributors to the longevity and long-term survival of the human race by nurturing not only their own offspring but grandchildren, as well.

Nature rewards humans and animals capable of devoting time and energy to offspring, thus ensuring the survival of the next generation, the theory suggests. Caregiving, in which an individual such as a grandparent shares personal resources, including food, time, money or wisdom, extends the usefulness of the caregiver beyond the fertile years, according to the theory:

New Theory

Ronald Lee, a professor of demography at Berkeley who used his own study to propose the new theory; said his findings extend the ” classic evolutionary theory on aging – that fertility is the determinant of a person’s life span.

“My theory says that reproductive fitness isn’t just about bearing offspring,” Lee said. “It’s about investing in each offspring. Mortality and deterioration with age are shaped by the amount of future investing that an average organism would do.”

Lee said the results of his study also suggest that nurturing behavior and human longevity evolved together over time. The study; which appeared in the Aug.l edition of the Proceedings of the National Academy of Sciences, appears to be supported by the fertility habits of animals, fish and insects.

After birth, all mammals including primates, all birds, many insects and some fish nurture their offspring, according to Lee’s study. Grandparents help out even though they

themselves are no longer fertile. For instance, post-reproduction bottlenose dolphins and pilot lot whales baby-sit, guard and even breast-feed their grandchildren, Lee’s study found.

Species that put all their effort into breeding and none into care giving, such as salmon, die shortly after reproduction. Species that perform minimal post-birth care, such as wasps, only live a brief time after breeding.

Intergenerational transfers

“The time and resources an individual puts into the next generation, what I call ‘intergenerational transfers,’ are important in determining the average life span of a species and the way it deteriorates with age,” Lee said.

Doris Reissue, 72, moved to Waco from California to be closer to her grandchildren. She helps take care of them when they are sick so her daughter does not miss work. She sees them several times a week.

“I missed seeing some of my other grandchildren grow up because we lived in California, so after I retired, I wanted to be close and enjoy the others while they are young,” she said of coming to Waco.

“I feel like I have something to contribute to their lives and enjoy spending so much time with them,” Reissue said.

Love and transference

Nine-year-old Savannah Reiske said she enjoys Grandma’s chocolate chip cookies, especially when she has to stay home sick from school. Savanna said she also likes history and hearing her grandmother tell stories about how things were when she was growing up.

Lee’s research looked back as far as 10,000 years ago, when humans were hunters and gatherers. He found that in certain primates, the gender that provides the primary care to offspring tends to have a higher life expectancy; a fact that may explain why women live longer than men, Lee said.

His “grandmother hypothesis” is that women experience menopause so they become free from their own childbearing to care for grandchildren.

Lee’s study was financed by the National Institute on Aging, and Richard Suzman, the NIA’s associate director, said the new theory on aging could be groundbreaking in its scope.

“This theory offers a fresh look at how longevity and nurturing behavior may have evolved and challenges pre-existing ideas about the nature of aging,” Suzman said.