When and why did Neanderthals go extinct? Explaining the loss of humanity's ancient siblings

Still, extensive academic debate among archaeologists persists on this topic. And, in regard to the question of why – and when – Neanderthals were driven to extinction, an uncertainty lingers.

When did Neanderthals go extinct?

Neanderthal extinction is thought to have occurred within an approximate window of 40,000 years ago, but the definitive date will always be elusive.

Archaeologists have settled on this timeframe by using radiocarbon dating on various Neanderthal tools and remains.

These are in locations scattered across Europe and Asia including Shanidar cave in Iraq, Vindija cave in Croatia, Simanya cave in Spain, and Gorham’s cave in Gibraltar, where physical evidence of Neanderthal life has been dated to as recently as 42,000 years ago.

Out of all the evidence that has been radiocarbon dated, almost none is proven to be more recent than this 40,000-year age (while plenty predates it).

This suggests that, with our current understanding, the period was a point of significant and serious population decline, if not outright extinction.

One caveat to this conclusion is that archaeologists may yet find evidence of Neanderthal populations existing more recently than 40 millennia ago – perhaps in small, isolated pockets and communities, which would reshape our understanding of their extinction. But, despite extensive searching for such evidence, none has yet been found.

• On the podcast | The Neanderthals: everything you wanted to know

Another caveat is whether it’s correct to consider Neanderthals extinct at all. British palaeolithic archaeologist Dr Rebecca Wragg Sykes argues that due to Neanderthal/Homo sapiens interbreeding, “most living people have a Neanderthal genetic legacy.” By extension, she draws the conclusion that Neanderthals are still with us today.

How and why did Neanderthals go extinct?

While archaeologists haven’t agreed conclusively on the definitive reason for Neanderthals’ extinction, current research supports the idea that it was due to a range of factors.

• Read more | 5 key facts about prehistoric cave art

These fit into two categories that may have played a significant role: competition with modern humans, and changes in the environment.

Did Neanderthals go extinct because of competition with Homo sapiens?

The belief that Neanderthals were in part made extinct due to contact with modern humans lacks direct evidence, but is firmly held by many archaeologists.

A crucial piece of the puzzle is that the apparent extinction of Neanderthals 40,000 years ago aligns with the movement of Homo sapiens into areas of Neanderthal inhabitation.

The idea of Homo sapiens – modern humans – and Neanderthals interacting is not just a supposition: we know that such interactions did occur, because the presence of Neanderthal DNA in our genome today proves that interbreeding between the populations took place.

• Read more | 8 little-known prehistoric sites in Britain

As Homo sapiens moved into formerly Neanderthal territory, did these interactions turn violent, and did the modern humans win these fights, ultimately leading to Neanderthal extinction? The answer to this question isn’t clear, as there is no unequivocal evidence of physical conflict between them.

Still, as Homo sapiens populations expanded into Neanderthal areas, it isn’t too difficult to imagine friction arising between groups, stemming from competition for vital resources like food and shelter.

One theory suggests that Homo sapiens killed their Neanderthal siblings unwittingly, by spreading into Neanderthal territory carrying diseases that the Neanderthal immune system had never been exposed to.

Another, put forward in a 2022 paper, suggests that Neanderthals could have been erased by sex, rather than disease or war. “This behaviour could have led to the Neanderthals' extinction if they were regularly breeding with Homo sapiens, which could have eroded their population until they disappeared,” explains Professor Chris Stringer in the paper.

Did Neanderthals go extinct because of environmental shifts?

Whether it’s asteroid impact, or changing global temperatures, changes in the environment have been the leading cause of extinction throughout natural history. It might have also been an integral factor in the demise of the Neanderthals.

Neanderthals lived during the last Ice Age. This was a period marked by dramatic oscillation between cold and warmer glacial periods, and archaeological analysis shows particularly harsh cold snaps may have coincided with Neanderthal population decline.

• On the podcast| British prehistory: everything you wanted to know

These events will have caused significant changes in the availability of vegetation, transforming the open woodlands Neanderthals favoured into less hospitable environments. This shift would have significantly impacted the populations of large herbivores – including mammoths and woolly rhinos – that were a mainstay of the Neanderthal diet.

Faced with rapidly shifting landscapes and the changing availability of essential resources, Neanderthals might have struggled to adapt, leading to dwindling populations and the knock-on effects of that.

Dovetailing with encroaching competition from Homo sapiens, the changing climate seems likely to have imposed the fate of extinction on Neanderthals, which left us as the final human species on the planet.

Whether or not one of these factors played a bigger role than another remains disputed. However, it brings researchers closer to understanding the truth behind when, why, and how Neanderthals ultimately faced extinction.