A Math Equation May Help Solve the Neanderthal Extinction Mystery

For decades, Neanderthals were considered secondary characters in our evolutionary history. They thrived throughout Ice Age Europe and Western Asia for hundreds of thousands of years until the arrival of modern humans. Soon after, the Neanderthals were extinct. Has climate chaos doomed them? Has our species surpassed them? Or have they simply been swallowed up by history?

A new mathematical model, published in Scientific reportsoffers a new answer.

“On a small scale Homo sapiens Immigrations into Neanderthal populations, causing recurrent mixing of genes, could have led to almost complete genetic substitution over 10,000 to 30,000 years,” the study authors said.

In other words, Neanderthals may not be extinct. Instead, they became We.

Learn more: The fascinating path of Neanderthal evolution: where did Neanderthals come from?

When Homo sapiens met the Neanderthals

Neanderthals originated in Eurasia around 400,000 years ago and adapted impressively to glacial extremes. They were the predominant hominids of the region, making sophisticated tools and hunting animals long before H. sapiens introduced himself.

Genetic and archaeological evidence suggests that “modern humans may have migrated from Africa to the Levant and then spread throughout Eurasia at the end of the Middle Paleolithic, approximately 45,000 years ago.”

These migrations did not occur in one giant wave, but rather in a long series of arrivals over thousands of years. Each wave created new opportunities for interaction, trade, competition, alliances and reproduction.

Today, most people living outside of Africa still carry a small percentage of Neanderthal DNA. This genetic inheritance suggests that the Neanderthal story was not one of extinction, but of absorption.

How does mathematics help tell the Neanderthal story?

The new study takes this idea of ​​genetic absorption and puts the math behind it. The mathematical model is based on species-neutral drift – a term meaning that no population needs a biological advantage to succeed. Instead, all they needed was a broader demographic and plenty of time.

Neanderthal groups were small, with only a few thousand individuals spread across a wide geographic area. In the meantime, H. sapiens the populations were much larger.

As described in the study, Neanderthal groups were like “islands”, whereas H. sapiens these groups constituted the “continent”. Each new wave of H. sapiens the immigrants brought somewhat more modern human DNA to the Neanderthal groups. Genetically, the effects worsen exponentially over time. A little genetic dilution in each generation results in dramatic changes over a few thousand years.

“Rather than sudden extinction, our model suggests that repeated cycles of H. sapiens Immigration leading to dilution of the Neanderthal gene could explain the disappearance of Neanderthals and the observed patterns of Neanderthal ancestry in modern human populations,” the research team explained.

Changing Neanderthal History

While perhaps a less exciting story of what happened to Neanderthals, this study aligns with genetic evidence of interbreeding between H. sapiens and the Neanderthals. This also implies that by the time Neanderthals became extinct, their genetic identity would have already been largely integrated into the modern human gene pool.

This mathematical model suggests that it is not necessary to resort to a dramatic Hollywood-inspired event – ​​such as a plague or a sudden climatic catastrophe – to explain the genetic disappearance of Neanderthals. Instead, a steady influx of modern human genes into the smaller Neanderthal pool could easily have done the job.

Learn more: Neanderthal vs Homo Sapiens: how are Neanderthals different from humans?

Article sources

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This article references information from a recent study published in the journal Scientific reports: A simple analytical model for Neanderthal extinction due to genetic dilution from recurrent small-scale immigrations of modern humans