Today’s question comes from Cadell, a fellow Advanced Ape. He claims to be Canadian, but I’ve never heard him apologise for anything so I’ve always been skeptical about his heritage. At any rate, he wanted my opinion on an article published on ScienceNews. It reports on a recent PENIS PNAS paper that provides new radiocarbon dates for 2 key Neanderthal sites in Spain.

Iberia is an area of great interest to palaeoanthropologists since it appears to contain the youngest evidence of Neanderthals anywhere. This suggests that Spain was their last refuge, which they retreated to in the face of encrouching Homo sapiens. There they clung on for a few thousand more years, before ultimatley going extinct for good. However, they survived for just long enough to co-exist with some modern humans, raising interesting possibilities about inter-breeding, Neanderthal/human hybrids and much more.

However, this nice little narrative is being challenged. The ScienceNews report in question summarises the PNAS paper as:

The story of the Neandertals may need a new ending, a controversial study suggests. Using improved radiocarbon methods, scientists redated two of the youngest known Neandertal cave sites and concluded that they are at least 10,000 years older than previous studies have found.

So will we all have to re-examine the extinction of Neanderthals? Yes, but not for the reasons ScienceNews gives. In fact, they seem to have gotten the story pretty badly wrong and are only right by coincidence. Allow me to explain.

A team of international researchers did indeed use new radiocarbon dating techniques to re-date several key Spanish sites from the time Neanderthals were going extinct. They were using ultrafiltration; a new method designed to remove tiny contaminants in bone so they can be dated more accurately. These new, more accurate dates were 10,000 years older for the earlier dates obtained for these Neanderthal sites. 

So far ScienceNews seems to be on the money.

However, this pushes the Neanderthal extinction right to the limit of what we can date with radiocarbon dating. It analyses two isotopes to determine how much time has past since the animal being examined died. However, one of these isotopes decays away until there is so little of it left we can’t get an accurate date. As such there is a limit on radiocarbon dating. Anything greater than 40,000 years old has a big question mark over it, anything over 60,000 years old can’t accurately be radiocarbon dated full stop. 

The new dates for these Spanish sites is 42,000 years old, placing them in the realm of “question mark.” So the big news here is that more accurate dates contradict other dates, but these new dates aren’t that reliable. Therefore we don’t actually have any idea when Neanderthals died out in the region and should try and find more evidence for when they disappeared. This is the ultimate conclusion of the PNAS paper and is a conclusion I agree with.

The researchers didn’t – as ScienceNews claims – try and suggest their new dates were the true dates for the Neanderthal extinction. That has yet to be determined.

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18 Comments

ralph gironda · 3rd April 2013 at 5:04 pm

It would be a lot easier if the bone from the skeleton was radiocarbon dated.

Date: Wed, 3 Apr 2013 13:36:30 +0000 To: [email protected]

    Adam Benton · 3rd April 2013 at 5:11 pm

    The conditions in the region mean it’s rare that the organic compounds used for radiocarbon dating rarely preserve. In the beginning this study tried to analyse many bones, but only 2 could be successfully dated.

Nuclear Wheelchair · 3rd April 2013 at 5:17 pm

So they died out in Europe before we spread there? Could it be that instead of being wiped out by us when we spread into Europe, that they were what kept us out?

    Adam Benton · 3rd April 2013 at 5:29 pm

    Under the traditional model their retreat from Europe was gradual. Humans and Neanderthals co-existed for a few thousand years, before they fled to the refuges in Spain and Siberia.

      Nuclear Wheelchair · 3rd April 2013 at 5:33 pm

      We gradually replaced them as they died out?

      Adam Benton · 3rd April 2013 at 5:38 pm

      The specifics are uncertain, but that’s certainly a possibility

      Nuclear Wheelchair · 3rd April 2013 at 5:49 pm

      Seems likely to me. You can imagine that the populations of Neanderthals and Denisovans to the North and East kept the people who left Africa contained in the Middle East. When they began dying out we were able to spread out across Europe and Asia replacing them.

      Just an idea.

        Adam Benton · 3rd April 2013 at 5:57 pm

        However, one must always be wary about jumping from claiming something is “plausible” to “true”

    Nuclear Wheelchair · 3rd April 2013 at 5:58 pm

    It’s an idea to be explored.

Nuclear Wheelchair · 3rd April 2013 at 6:31 pm

I mean, it’s a more likely scenario than people triumphantly marching across Europe and Asia wiping out other human species they come across. I imagine our ancestors were scared of the much more heavily built (and probably violent) Neanderthals and Denisovans. They must’ve seemed like monsters to them.

    Adam Benton · 3rd April 2013 at 6:50 pm

    However, we know that humans and Neanderthals lived side by side for some time; even interacted positively. It seems that we happily co-existed, but Neanderthals were on the decline and gradually disappeared. The notion of direct competition, or even violence amongst the other species is poorly evidenced. It’s pure speculation to talk about how our ancestors may have responded to them.

      Nuclear Wheelchair · 3rd April 2013 at 6:55 pm

      What evidence is there that we were on friendly terms with Neanderthals?

      Adam Benton · 3rd April 2013 at 6:56 pm

      Around the time humans arrive in Europe the Neanderthals suddenly start producing human-like technology. There was probably some learning/teaching interactions occurring.

      Nuclear Wheelchair · 3rd April 2013 at 7:17 pm

      That hardly proves we positively interacted that much. Maybe they just copied artifacts of ours that they found.

      A strong piece of evidence that we didn’t interact much is how little interbreeding there was. That we have only acquired a few percent of Neanderthal DNA after living beside eachother for thousands of years suggests to me that we didn’t interact that much.

        Adam Benton · 3rd April 2013 at 7:48 pm

        Except they were manufactured the same way. There are many ways to make a blade, but humans and Neanderthals both just happened to use the same way? Unlikely.

        Genetic data does suggest that what interaction there was only occurred on a limited scale. However, since we don’t have any human DNA from the period we can’t say for sure. It may be that 40,000 years ago there were populations of humans with 25% Neanderthal DNA

paullev · 3rd April 2013 at 6:36 pm

for more speculation on Neanderthals in Spain, see The Silk Code

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