Caspari analyzed a trove of 120,000-year-old Neandertal fossils from the site of Krapina in Croatia. Excavated more than 100 years ago, the assemblage contains bones of 75 to 83 individuals, which apparently accumulated within 10,000 to 20,000 years. Caspari estimated their age at death from the teeth; in young people, teeth are generally pristine, while the enamel is worn away in older people. And over time, a tooth's pulp cavity shrinks as additional dentine is deposited into it. In a new method, Caspari used nondestructive micro CT scans to measure pulp cavities.
The increase in elders could have had profound consequences for behavior and culture, such as the magnificent cave paintings in France. "Could this increase in adult survivorship account for the Upper Paleolithic explosion of art?" Caspari asked.
Older adults can care for and transmit culture to the young, and more adults means a larger population, which most researchers agree spurs cultural innovation. "I think this helped drive modern human behavior," Caspari said. She notes that modern humans from the same time period as Krapina also seemed to have died young. "It's not necessarily a species thing," she said.
It's risky to base big conclusions on a single assemblage, warned Alan Mann of Princeton. But Caspari's presentation was thought-provoking, said Leslie Aiello, president of the Wenner Gren Foundation for Anthropological Research. "Think of all those little orphan Neandertals," she said. "They must have been living on a knife edge."