Diet, brains, murder at the hands of a certain species called Homo sapiens, life expectancy: These and more have been floated as reasons to explain the vexing question: Why did Neanderthals die out about 30,000 years ago while our ancestors persisted? In a study in this week's Proceedings of the National Academy of Sciences, Erik Trinkaus argues that we should scratch the last one—life expectancy—off the list. His wide-ranging survey of Neanderthal and early human remains shows that our ancestors had no particular advantage over the Neanderthals in living into old age.
Dr. Trinkaus studied fossil records of humans from across Eurasia and of Neanderthals from the western half of Eurasia to estimate adult mortality in the two groups. He found that there was approximately the same number of adults in the 20-to-40 age range and over-40 age range in both groups. [The New York Times]
That era was no time for old men. Only about a quarter of Neanderthals and early humans that Trinkaus found lived into their 40s. He notes that it's possible both the Homo sapiens and Neanderthals had more elderly folks than the study would suggest, but that the demands of chasing food meant leaving the older members of the societies behind if they couldn't go on. If those remains were scattered, they are less like to be discovered and entered into the fossil
record.
"All the samples have a dearth of older individuals, which should reflect a complex combination of low life expectancy for adults, demographic instability, and the demands of mobility," he said. "If indeed there was a demographic advantage for early modern humans, at least during transitional phases of Late Pleistocene human evolution, it must have been the result of increased fertility and/or reduced immature mortality." [AFP]
Whatever the true reasons that Neanderthals disappeared, they are, of course, still lurking in our genes
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Image: flickr / Ryan Somma
