Biology Magazine

How Similar Were Neanderthals and Humans?

Posted on the 28 January 2016 by Reprieve @EvoAnth

We lived alongside Neanderthals for thousands of years. But whilst we kept on living, they ultimately went extinct.

For years researchers speculated about possible differences between our two species. Reasons why we survived, but they died out.

However, it turned out most of these differences don't actually exist.

This raises the question. Just how similar were the Neanderthals to us anyway?

Secret similarities

Why did one species of human flourish, whilst another died out? That's always been the big mystery about the Neanderthals.

In fact, it's even more curious than that. The Neanderthals were in many ways better than us. They had bigger brains, stronger muscles, and were more adapted to the cold climate of Europe. They had every advantage, yet were still unable to compete with us.

Researchers speculated that there must be some major difference between us. Something that gave us the advantage over them, despite their adaptations. Long lists of possible differences were developed. Perhaps we had a more varied diet, so were less vulnerable to prey vanishing. Perhaps our bodies were more efficient, so we needed less food. Maybe they hadn't mastered fire yet, so couldn't cook their food. We could have been more innovative, and generally smarter overall. It could be that they couldn't throw very well, forcing them to engage in risky, close combat hunting.

The list of speculation grew and grew, but ultimately didn't lead anywhere. Almost every major advantage humans were hypothesised to have doesn't actually exist.

They ate a variety of different food. They had cooked their food. They could have thrown their spears. Their bodies were still very efficient. They were innovative and produced advanced technology. They even made various forms of art.

All of this raises the question: just how similar were we? Apart from a handful of superficial differences, was there anything significant that separated our two species?

Different brains

Spoiler: Yes. There are some pretty key differences between modern humans and Neanderthals. And most of them are found in the brain.

In particular, there are some fairly major differences in the shape of our brains. As Neanderthals had more muscle mass, their brain wasn't any bigger than ours - relative to the body size. However, the shape of that brain was very different.

These differences mostly consist of a long list of boring anatomical terms. Plus, I've talked about this before. So to save you the torment of having to parse sentences like "These bulging parietals may have been linked to neural reorganization of component structures such as the precuneus" I'll simply provide a brief summary. If you're interested in a bit more depth, head over to the previous post.

So, briefly:

  • Once body size was taken into account we actually had larger brains than the Neanderthals
  • We have a larger parietal lobe, a bit of brain important in various higher order cognitive functions.
  • Neanderthal brains grew in a different way
  • We have a wider orbitofrontal cortex, linked to theory of mind amongst others
  • Our cerebellum is bigger
  • They had bigger occipital lobes (linked to vision and senses).

Different behaviour

So, it's fairly clear there were some big differences between the human and Neanderthal brain. But the real question is whether or not they matter.

Sure, there might be tonnes of differences in the shape of the brain; but unless that has an actual impact on the species it doesn't really matter. Fortunately for all of us trying to maintain some sense of superiority over the Neanderthals, this does seem to be the case.

Generally speaking, the shape of our brain made it a lot more globular. Yes, that's the technical term. This shape effectively shortens the distances between various parts of the brain. Combined with the increases in the parietal lobe, this could give us an edge in working memory. This is basically the ability to hold ideas in your head and mentally manipulate them.

But the question still remains: what's the big deal with working memory? Does it matter that we had a better version of it?

Well, it seems that it did give us a few subtle special abilities. On the surface they might not seem as exciting as the old (disproven) differences between humans and Neanderthals. Like fire use. But these still add up to something special. For example, some speculate that humans - with our great working memory - might have been able to trap prey. This would make it a lot easier to hunt - and kill - large numbers of prey.

Unfortunately the only evidence we have of such traps is circumstantial. Like large numbers of prey, which could be caused by some other (albeit unlikely) things. So it's clear that whilst there are some big differences between our brains, how these would manifest is still a bit iffy.

tl;dr

Neanderthals were a lot more similar to modern humans than we thought, but they were still very different.

References

Wynn, T., Overmann, K.A. and Coolidge, F.L., 2016. The false dichotomy: a refutation of the Neandertal indistinguishability claim. Journal of Anthropological Sciences, 94, pp.1-22.


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