According to a paper published in Science, models of how animal and plant distributions are affected by climate change may also explain aspects of human evolution.
The
approach takes existing knowledge of the geographical spread of other
species through the warming and cooling of the ice ages to provide a
model that can be applied to human origins.
“No
one has applied this knowledge to humans before,” said Dr John Stewart,
lead author on the paper and researcher at Bournemouth University.
“We
have tried to explain much of what we know about humans, including the
evolution and extinction of Neanderthals and the Denisovans (a newly
discovered group from Siberia), as well as how they interbred with the
earliest modern populations who had just left Africa. All these
phenomena have been put into the context of how animals and plants react
to climate change. We’re thinking about humans from the perspective of
what we know about other species.”
Climate
is believed to be the driving force behind most of these evolutionary
processes, including geographical range change. It dictates which
species are where at what time, driving their geographical spread or
contraction.
Dr Stewart continued: “Ultimately, this model explains why Homo sapiens as a species are here and the archaic humans are not.”
The
research also leads to interesting conclusions as to how and why
Neanderthals, and indeed the Denisovans, evolved in the first place.
“One
of the models we’ve formulated is that the adoption of a new refugium
(an area of refuge from the harsh climatic conditions of the Ice Age) by
a subgroup of a species may lead to important evolutionary changes,
ultimately leading to the origins of a new species. In fact this could
apply to all continental species, whether animals or plants” said Dr
Stewart.
Co-author
Professor Chris Stringer of the Natural History Museum, London, said
“these ideas may well explain how new human species such as Homo antecessor and Homo neanderthalensis evolved
in Eurasia. The concept of refugia may also explain why the
hypothesized interbreeding events between modern humans and Neanderthals
and Denisovans occurred in the south of Eurasia rather than further
north.”
The
paper, entitled “Human Evolution Out-of-Africa: The Role of Refugia and
Climate”, by Dr. John Stewart of Bournemouth University and Professor
Chris Stringer from the Natural History Museum, is published in Science
on Friday 16 March 2012.
