Long-lost cousins

What do new discoveries about how Neanderthal man lived and died tell us about our human ancestors?

A Neanderthal man in profile: DNA recovered from a 38,000-year-old leg bone unearthed in a cave in Vindija in Croatia has become part of a landmark project to read the entire genetic sequence of our ancient human ancestor. Photo: Corbis

Your historical ancestors are unlikely to have done anything remotely interesting. But your prehistorical ones almost certainly did. Like a form of deep genealogy, tracing our origins back thousands and millions of years is a branch of science that never fails to capture the public’s imagination.

At Nature, we often find that our most read, downloaded or listened to studies are those about our more ancient relatives, whether it’s the hobbit of Flores or the oldest human ancestor, Toumai. Last week, a paper in the journal Cell uncovered the first completed sequence of the Neanderthal genome, and some fascinating insights into our evolutionary cousins. Expect more revelations from this project very soon.

The demise of the Neanderthals is one of the great mysteries about the origin of our species. They were on a side branch in the human tree, co-existing with our direct ancestors for maybe 100,000 years. Their physical appearance has helped generate a bad rep, their being short, stocky and heavily browed. But these traits are only unattractive to us in the same way that a chimp might not fancy an orang-utan.

Indeed, although it’s been speculated about often, last week’s paper suggests that there was probably very little interbreeding. The new data put the last common ancestor of Neanderthals and modern humans at around 660,000 years ago. That may seem like a long enough time without sex to be vastly different species, but in an evolutionary timescale it’s the gap between a couple of one night stands.

From fossils and more recently genetic analysis, in terms of behaviour, Neanderthals and humans share many characteristics. They weren’t the knuckle-dragging grunters of fiction. It’s well established that they ritually buried their dead, made tools and explored from the westernmost tip of Europe, well into Asia. They may have been capable of speech, as they had anatomical and genetic characteristics that are very similar to those that enable speech in us. There’s even good genetic evidence that some Neanderthals had ginger hair and fair skin.

So what brought about the fall of the house of Neander? Of the many theories, one stands out as being distinctly modern: genocide.

Some lines of evidence suggest humans hunted their low-browed but smart cousins into oblivion. It’s not difficult to argue that humans are an unusually aggressive species. Our desire to conquer, kill or forcibly impose our will upon others is probably culturally universal, and goes well beyond survival. We were almost certainly better toolmakers and better hunters than Neanderthals. We may have competed for the same resources and shelter. Wiping out this species would have been an easy job.

But we should be careful about using evocative words like “genocide”. It’s tempting to speculate about this aggression in our ancestors as if it tells us something about our present. Genocide is a modern concept set in history rather than prehistory, such as in Rwanda where 100,000s of Tutsis were systematically murdered. To speculate about a Neanderthal genocide is wholly misleading. Neanderthals probably lived in very small groups and may have existed in global populations of as little as 10,000 at any one time. They may have been teetering on the brink of extinction for 1,000s of years. It looks as though the arrival of modern humans in their habitat speeded up their demise, but to invoke genocide suggests some sort of intentionality and strategic planning for which we simply have no evidence. More likely is that a combination of factors was at play, but basically, Neanderthals were the victim of that not cruel, but totally indifferent force of natural selection.

What does learning about our evolutionary origin tell us about ourselves today?

There are some things that we can understand: such as how western obesity is an artefact of our evolutionary past. Very recently and very quickly, our social development has led us to spend a lot of time eating cheeseburgers and mucking around on the internet. But our bodies are still stuck in a time when fatty and salty foods were hard to come by and therefore were sought out. Now, they are everywhere and our bodies can’t cope. That’s not to excuse unhealthy behaviour, merely to explain why it is unhealthy.

It’s the same fascination that renders paleoanthropology and genealogy so popular. The detective work in human evolution is a tad trickier, and the evidence less forthcoming. But, ultimately, the drive is the same: a curiosity about our past. Except that it’s not really our past, and what both tell us about our own lives is limited. Genealogy is actually nosey micro-history. Aside from specific cases determined by heritable genetic diseases, the influence of each previous generation diminishes rapidly.

Human evolution sits, rightly, as a branch of science that provokes genuine wonderment. It’s actually my favourite subject. The Neanderthal genome project is truly a scientific and technological marvel. It will reveal many incredible things about an important species. But just as knowing something about who your great great great grandmother’s brother married is finally a matter of idle curiosity, it won’t tell us that much about ourselves now.

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