Are Neanderthals really a separate species to us? 🙈

Everyone alive today, except those with exclusively African ancestry, has around 2% Neanderthal DNA. This means that when our species migrated into Europe and Asia, we bred with Neanderthals in a small, but significant way. But this poses an interesting question: are Homo sapiens and Neanderthals really two different species?

Me and a Neanderthal!

On the one hand, as I discussed in my previous Neanderthal video, various “morphological” differences like skull shape, build, and thickness of skin and hair suggest separate evolutionary tracks. And yet... a widely used definition of the term “species” calls this into question.

The “biological species” definition states that species are “reproductively isolated entities”. So, if two individuals can mate and produce fertile offspring, then they're classed as the same species. But if two individuals either can’t produce offspring at all, or can’t produce fertile offspring, then they're not the same species. Modern genetics proves beyond doubt that Neanderthals did successfully breed with Homo sapiens. Therefore, according to the biological species definition, they can’t be classed as a separate species to us!

I consider there to be two strong responses to this argument:

• Firstly, there is growing evidence that infertile offspring were a common result of our sexual encounters. Therefore, interbreeding between Neanderthals and Homo sapiens was, in fact, often unsuccessful.

• Secondly, research shows that various species, including baboons, wolves, dogs, bears and large cats do successfully interbreed on a regular basis! In particular, its currently estimated that 16% of all bird species interbreed naturally in the wild!

Therefore, I don’t think it should be a question of whether Neanderthals are the same species as modern humans. I think, instead, we should be asking whether the biological definition of species should be abandoned, and replaced with an alternative.

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