For decades, the disappearance of Neanderthals has been one of the biggest mysteries of human evolution. It happened about 40,000 years ago, suspiciously coincident with our species Homo sapiens to Eurasia… But now we are thinking that they did not become extinct.
What was thought. Classical theories paint a replacement scenario: either we wiped them out in direct competition, or they couldn’t withstand brutal climate change. But now a study published in Scientific Reports offers a much more fascinating answer: we absorb them among ourselves. And the key to all this is genetic dilution.
The hypotheses. To go deeper, the competition hypothesis suggests that Homo sapiens We were simply superior: we had better hunting strategies, a broader diet or more advanced social structures that allowed us to monopolize all the resources, driving the Neanderthals to extinction.
On the other hand, the environmental hypothesis blames the drastic climate changes that occurred just at that time. According to this idea, Neanderthals could not adapt to extreme fluctuations and their populations fragmented until they disappeared permanently.
However, the new study presents a mathematical model that leaves both factors aside and focuses on the most basic of all: demographics and sex.
The new model. The authors of the study propose an analytical model that demonstrates how Neanderthals could disappear without the need for the Homo sapiens had any selective advantage over them. The model does not require “catastrophic events” or cognitive superiority. Instead, it relies on a concept called “species-neutral drift” and a key factor: small, recurring immigrations of Homo sapiens in Neanderthal territories.
There were many more of us. One of the first ideas pointed out in this case is that the population Homo sapiens that left Africa was much larger in number than the Neanderthal, acting as a “practically infinite demographic reservoir.”
By going together, because friction makes affection, and between the species they began to intersect and had very fertile offspring. The model assumes that this was not a one-time event, but rather a “sustained gene flow” that occurred every time a small group of modern humans arrived in an area.
So, adding that the Neanderthal population was much smaller and there was a constant influx of genes from Homo sapiensthe result is the dissolution of the gene pool. It’s literally like pouring a glass of Neanderthal water into an ocean of Homo sapiens. In the end his presence is completely diluted.
The time. The most powerful thing about the study is that its calculations fit with the archaeological record. The mathematical model shows that this process of “almost complete genetic replacement” could have occurred within a period of 10,000 to 30,000 years, something that aligns with the long period of coexistence that both species had in Eurasia.
Were they extinct? This is the question we ask ourselves. Know if the word ‘extinction’ is appropriate for this paradigm. This model offers what scientists call a “parsimonious explanation” (the simplest). In words we understand, it does not deny that other factors, such as competition or weather, could have contributed. But it shows that this genetic dissolution alone is something that may have explained the disappearance of the Neanderthals.
That is why, rather than an extinction, we speak of a fusion by absorption. This perfectly explains why the Neanderthals disappeared as a genetically distinct group, but their legacy endures: modern humans of Eurasian ancestry conserve in our DNA a small percentage of their genetic heritage (although very diluted).
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