Neanderthals were already on the verge of extinction in Europe by the time modern humans arrived on the scene, a study suggests.
DNA analysis suggests most Neanderthals in western Europe died out as early as 50,000 years ago - thousands of years before our own species appeared.
A small group of Neanderthals then recolonised parts of Europe, surviving for 10,000 years before vanishing.
The work is published in the journal Molecular Biology and Evolution.
An international team of researchers studied the variation, or diversity, in mitochondrial DNA extracted from the bones of 13 Neanderthals.
This type of genetic information is passed down on the maternal line; because cells contain multiple copies of the mitochondrial genome, this DNA is easier to extract from ancient remains than the DNA found in the nuclei of cells.
The fossil specimens came from Europe and Asia and span a time period ranging from 100,000 years ago to about 35,000 years ago.
The scientists found that west European fossils with ages older than 48,000 years, along with Neanderthal specimens from Asia, showed considerable genetic variation.
But specimens from western Europe younger than 48,000 years showed much less genetic diversity (a six-fold reduction in variation compared to the older remains and the Asian Neanderthals).
In their scientific paper, the scientists propose that some event - possibly changes in the climate - caused Neanderthal populations in the West to crash around 50,000 years ago. But populations may have survived in warmer southern refuges, allowing the later re-expansion.
Low genetic variation can make a species less resilient to changes in its environment, and place it at increased risk of extinction.
"The fact that Neanderthals in Europe were nearly extinct, but then recovered, and that all this took place long before they came into contact with modern humans, came as a complete surprise," said lead author Love Dalen, from the Swedish Museum of Natural History in Stockholm.
"This indicates that the Neanderthals may have been more sensitive to the dramatic climate changes that took place in the last Ice Age than was previously thought."
Neanderthals were close evolutionary cousins of modern humans, and once inhabited Europe, the Middle East and Central Asia. The reasons behind their demise remain the subject of debate.
The appearance of modern humans in Europe around the time of the Neanderthal extinction offers circumstantial evidence that Homo sapiens played a role. But changes in the climate and other factors may have been important contributors.
"The amount of genetic variation in geologically older Neanderthals as well as in Asian Neandertals was just as great as in modern humans as a species," said co-author Anders Gotherstrom, from Uppsala University.
"The variation among later European Neanderthals was not even as high as that of modern humans in Iceland."
The researchers note that the loss of genetic diversity in west European Neanderthals coincided with a climatic episode known as Marine Isotope Stage Three, which was characterised by several brief periods of freezing temperatures.
These cold periods are thought to have been caused by a disturbance of oceanic currents in the North Atlantic, and it is possible that they had a particularly strong impact on the environment in western Europe, note the researchers.
Over the last few decades, research has shown that Neanderthals were undeserving of their brutish reputation.
Researchers recently announced that paintings of seals found in caves at Nerja, southern Spain, might date to 42,000 years - potentially making them the only known art created by Neanderthals. However, this interpretation remains controversial.
Well, we aren't to blame for that one after all.
The article is suggesting that our impact on the Neanderthals was less severe on the basis of DNA studies. All we can know for sure is that Neanderthals were extant when we entered their domain. We are responsible for the extinction of many great species and I would still include the Neanderthals in the category.
Thanks for the interesting article -- very informative.
Quite interesting. Seems like our cousins were quite resilient. We ( homo sapiens sapiens) almost became extinct at a couple of times in our past also. Species Homo, just amazing. Just wished some of our brothers had made it too. Would have been fantastic.
It has only taken us 60,000 or so years to reach a population of 7 billion so when, in our short history, did we nearly nearly get wiped out ? After a small group of us left Africa we followed the sunrise and reached as far as Australia in a very short time. So in addition to our African homeland, we were dispersed over 2 continents and a sub-continent at 50,000 to 60,000 years ago.
Watched a show on PBS that followed the genetic drift of humanity. According to the evidence, we came down to approximately 4 small groups, comprising 30-100 individuals each. Maybe 500 individuals in all, app 100,000 to 130,000 years ago. And from that, all the silly, crazy, beautiful, boring, interesting, (insert adjective here) people that makes up us. Humanity. We are truly one, genetically. Still, wish some of our fellow homo species had made it.
If so, that happened in Africa.
I agree it would be great if Homo Erectus was still with us. They were good enough to make fire and migrate as far as Java in Indonesia and Western Europe. They never made it to Australia or the Americas though.
Yes, it was while we were still in Africa. Also, Erectus made tools, evidence they had funerary rites, i.e. buried thier dead, made jewelery, etc. Thier only mistake is that they were at the beginning, and if you watch a NASA launch, at first a rocket takes off slowly. Takes awhile to get going, and much of the fuel is burned at the beginning. My analogy. So early humans were there to be burned off, leaving us to make it to orbit. We are the culmination of them all. Just hope we have a soft landing! Peace and long life, my friend.
The near human extinction is theorized to have been caused by the super volcano, Toba, eruption.
The Toba super eruption was a super volcanic eruption that occurred some time between 69,000 and 77,000 years ago at Lake Toba (Sumatra, Indonesia). It is recognized as one of the Earth's largest known eruptions. The related catastrophe theory holds that this event plunged the planet into a 6-to-10-year volcanic winter and possibly an additional 1,000-year cooling episode. This change in temperature resulted in the world's human population being reduced to 10,000 or even a mere 1,000 breeding pairs, creating a bottleneck in human evolution.
The lower number could well have doomed Human Beings as it represents a very narrow gene pool (unless there was a random, world wide selection thing going ...or maybe Noah picked up hitch hikers) – the general rule is that a very heterogeneous gene pool has a poor adaptability to changes in the environment and is unlikely to survive over the long term. Human genetic divergence, considering the entire human population is less than 0.02% divergence. But for the fact that we were smarter that the predators and had something they didn't – thumbs - and a hand that could manipulate their environment, we would have failed the evolutionary tests faster than a naked monkey on two legs in big nasty, long toothed cat land.
I think the big question is, where were we at the time ? Confined to Africa or spread out as far as India or even Australia ? If so, how could the human population be reduced to such a small number over such a long distance and survive ?