Prehistoric Graves Reveal Americas' First Baby Boom
According to the theory, populations swell when societies shift from a nomadic hunter-gatherer lifestyle to one based on the more sedentary routine of farming.
Staying put allows women to have more babies, and a farming economy provides more food to support the growing population, explained Jean-Pierre Bocquet-Appel, a researcher at the National Center for Scientific Research in Paris.
North America's first baby boom is reflected in the number of skeletons of children ages 5 to 19 found in ancient cemeteries across the continent, he said.
"That doesn't mean the living condition was worsening," Bocquet-Appel said. "It means there were plenty of young people everywhere, and because there were plenty of young everywhere, there were plenty of young who died."
When populations are stagnant or decreasing, by contrast, graveyards are full of old people but few young, he added. According to the theory, a cemetery's population reflects the living population around it.