Cavemen once lived with modern humans for over 5,000 years and exchanged genes

In some parts of France and Spain, the two species had a rocky relationship for a really long time.
Rupendra Brahambhatt
Illustration of a Neanderthal dressed like a modern human.
Illustration of a Neanderthal dressed like a modern human.

Photo by Crawford Jolly on Unsplash 

A team of archaeologists at Leiden University in the Netherlands has found surprising evidence suggesting that modern humans (Homo sapiens) once co-existed with extinct species of ancient humans called Neanderthals (Homo neanderthalensis). Both species may have lived together in some parts of France and Spain for over 5,000 years, and according to the researchers, back then, they didn’t just meet but also interbred.

These findings are also in alignment with many previously published studies that highlighted the presence of Neanderthal DNA in modern humans. Homo sapiens and Neanderthals are believed to have cohabited between 1,400 and 2,900 years ago before the ancient species went extinct. The researchers believe that apart from the exchange of genes, a lot of other exciting events may have also happened during that time.

Explaining this further, the first author and Ph.D. candidate at Leiden University, Igor Djakovic told IE, “During this period when Neanderthals and Homo sapiens likely co-existed in Europe, there were substantial transformations in material culture. It was likely a time when new ideas and knowledge were rapidly spreading through and between different human groups – possibly due to the increasing interaction between these two long-separated human lineages. It was, in all likelihood, a very interesting time to be alive.”

Archaeological evidence of the co-existence

Cavemen once lived with modern humans for over 5,000 years and exchanged genes
Artifacts (stone knives) created by probably the last Neanderthals of France and northern Spain.

According to Natural History Museum, Neanderthals first appeared approximately 400,000 years ago. Interestingly, they went extinct around the same time when Homo sapiens started to become the dominant human species i.e. about 40,000 years ago. So it is highly likely that at one point in time, the two species occupied the same regions.

During their study, the researchers examined two collections of artifacts (this term is used for referring to ancient man-made objects in archaeology) recovered from 17 archaeological sites in northern Spain and France. Radiocarbon dating of these artifacts revealed that the first collection comprised 28 Neanderthal artifacts and the second collection contained an equal number of objects created by Homo sapiens.

In order to further confirm their age and the human species to which the artifacts belonged, the researchers employed two advanced and widely accepted techniques known as Bayesian modeling (BM) and Optical Linear Estimation (OLE). The former is used to overcome the imprecision inherent to radiocarbon dating. It does not produce a single date but rather a probability range, for instance, the model estimated that modern humans inhabited northern Spain between 42,653 and 42,269 years ago.

OLE on the other hand predicts the extinction date of animals based on their last known appearances in the fossil record. It operates under the assumption that one can never in fact find or date the ‘first’ or ‘last’ member of a species. It uses the dates for the last known occurrences to estimate how much longer the species may have existed before its eventual extinction.

The data from the two methods suggested that Neanderthals went extinct between 39,894 and 39,798 years ago and their artifacts were in France and Spain for a time period ranging between 5,449 and 4,470 years. Since humans also inhabited the same region about 42,000 years ago (the exact range is mentioned in the paragraphs above), the authors calculated that both species thrived together in Europe between 1,400 and 2,900 years before the cavemen went extinct.

How did the two species react to each other?

Cavemen once lived with modern humans for over 5,000 years and exchanged genes
Painting depicting a Neanderthal family in a cave.

Before we jump into the relationship that Neanderthals and modern humans might have shared with each other, it is important to understand that the findings of the authors do not point out the exact time and place where the two species may have co-existed. Moreover, the results predicted by the models are only as accurate as the data entered into them.

According to the researchers, the current results are based on the most robust, up-to-date, and high-quality data. However, when new evidence will come in from further radiocarbon dating of more samples, these models will have to be adjusted.

For now “we need to keep in mind here is the time depth – in all likelihood, there is no single scenario for the nature of their relationship when they co-existed in any given region. In some cases, they (Neanderthals and modern humans) probably lived together and raised children, in others they tried to avoid each other, and in some they probably had conflicts, Djakovic told IE.

“I suspect that they were likely more cooperative than we tend to imagine. We now know that they at least occasionally exchanged genes, as most people living today carry some Neandertal DNA,” he added further.

As part of their Neandertal Legacy project, Igor Djakovic and his team are currently conducting new excavations at a site in central France that preserves occupations of the last Neandertals in the region. They want to begin filling in the gaps concerning the nature and frequency of the interactions between Neanderthals and Homo sapiens prior to their disappearance.

The study is published in the journal Scientific Reports.

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