Fertility gave early humans an edge

WASHINGTON U.-ST. LOUIS (US) — Increased fertility and/or reduced immature mortality—not longevity—is what gave early modern humans a demographic advantage over Neandertals.

In fact, life expectancy was probably the same for early modern and late archaic humans and did not factor in the extinction of Neandertals, according to a new study.

An examination of the fossil record to assess adult mortality for both groups, which co-existed in different regions for roughly 150,000 years, shows the proportions of 20 to 40-year-old adults versus adults older than 40, were about the same, says Erik Trinkaus, professor of anthropology at Washington University in St. Louis.

This similar age distribution reflects common patterns of adult mortality and treatment of the elderly in the context of highly mobile hunting-and-gathering human populations.

The study is reported in the Proceedings of the National Academy of Sciences.

Older individuals are rarely found among the remains of late archaic humans, which has prompted some researchers to propose that Neandertals had an inherently shorter life expectancy, contributing to their demise.

“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,” writes Trinkaus in the paper’s conclusion.

“Neither adult longevity nor proposed modest shifts in developmental rates are likely to have played a role in this demographic transition.”

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