Magazine article Science News

Living Long in the Tooth: Grandparents May Have Rocked Late Stone Age

Magazine article Science News

Living Long in the Tooth: Grandparents May Have Rocked Late Stone Age

Article excerpt

A memorable senior moment may have occurred toward the end of the Stone Age. Around 30,000 years ago, the number of people surviving long enough to become grandparents dramatically increased, altering the social landscape and provoking major cultural innovations, according to two anthropologists.

Their analysis of fossil teeth from human ancestors indicates that Homo sapiens from the late Stone Age--but not Neandertals or other members of our evolutionary family--exhibited a sharp rise in the population of individuals older than 30 years. Data from hunter-gatherer groups today suggest that among prehistoric H. sapiens, women first bore children at about age 15 and would have become grandmothers at around age 30, say Rachel Caspari of the University of Michigan in Ann Arbor and Sang-Hee Lee of the University of California, Riverside.

Caspari and Lee theorize that prehistoric grandparents sparked growth among Stone Age populations by caring for grandkids. The resulting larger populations developed complex social systems, the researchers suspect, which fostered the explosion of artwork and ornamentation, such as that discovered previously by archaeologists.

"Increased longevity came late in human evolution and may explain the big time lag between the origins of modern human biology [at least 200,000 years ago] and modern human behavior," Caspari says.

The new report appears in an upcoming Proceedings of the National Academy of Sciences.

Caspari and Lee studied the fossil teeth of 768 adults from four groups in the human evolutionary family: australopithecines that lived from 3 million to 1. …

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