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.
Earlier Neanderthal demise than previously thought? @evoanthsciencenews.org/view/generic/i…
— Cadell Last (@cadelllast) March 29, 2013
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.
