Conclusions based on thirteen
samples are at best suspect and this lot is no different. The underlying assumption is that the
Neanderthals were somehow inferior and thus died out. Yet they had one extra gene than we do.
The evidence, by the by, conforms
nicely to my conjecture that the Neanderthals migrated to the continental shelf
and participated in the first rise of human modernity. We have even tightened up the time frame to
48,000 years ago. That a select
population reentered the original homelands is not unreasonable at all in this
scenario.
My point is to rid ourselves of a
very dangerous assumption that has dogged research on Neanderthals for a
century. They are not deficient humanity at all and may well have been far
better adapted to harsh temperate climes than we ever were. The proposition that they helped in the first
human emergence is quite reasonable.
What the evidence does do is
sharply underline the importance of the transitional date of 48,000 year ago
when the Neanderthals effectively vacated the continental climate zone. Plausibly they discovered lowland agriculture
and made a far easier living, just like today when no one relies on hunting
whatsoever anymore even if they could.
DNA reveals Neanderthal extinction clues
By Paul RinconScience editor, BBC News website
Neanderthals were close evolutionary cousins of our own species - Homo
sapiens
27 February 2012 Last updated at 13:14 ET
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.
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 (variation in the older remains and the Asian
Neanderthals was six-fold greater than in the western examples).
Neanderthals may have been more sensitive to the dramatic climate
changes... than was previously thought”
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
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