Sunday, 25 September 2011

New Evidence Suggests That Climatic Fluctuations Drove Human Evolution

A stone arrow head, used by Dr Matt Grove, who's
date matches a warm fluctuation in the Earth's past climate
A team of researchers from the University of Liverpool have found that a series of climatic fluctuations almost perfectly match the appearance of various biological innovations in human human evolution. The researchers, led by Dr Matt Grove from the School of Archaeology, Classics and Egyptology, correlated dates ranging from the appearance of early hominids all the way up to the creation and spread of stone tool technology with climatic fluctuations and found that key events coincided with periods of warmth.

The study showed that an onset of high climatic variability around 2.7 million years ago coincided with the evolution of more advanced hominids such as Homo habilis and Homo erectus. Stone tools coincide with a climatic event 2.6 million years ago and finally, when the climate fluctuations peak, all primitive hominid species disappear, leaving behind Homo erectus, the ancestor of modern humans. Homo erectus was the first hominid to leave Africa and was widespread for over 1.5 million years due to its adaptability against climate change.

Dr Grove said 'the study confirmed that a major human adaptive radiation - a pattern whereby the number of coexisting species increases rapidly before crashing again to near previous levels - coincided with an extended period of climatic fluctuation.' Dr Grove's research is the first to explicitly model 'Variability Selection', an evolutionary process proposed by Professor Rick Potts in the late 1990s, and supports the idea that rapid climatic fluctuations directly influenced human evolution. 

Variability selection suggests that evolution, when faced with rapid climatic fluctuation, should respond to the range of habitats encountered rather than to each individual habitat in turn; the timeline of variability selection established by Dr Grove suggests that Homo erectus could be a product of exactly this process. Linking climatic fluctuation to the evolutionary process has implications for the current global climate change debate as its effects could be used to interpret the future of our planet. 

Dr Grove said: 'though often discussed under the banner term of 'global warming', what we see in many areas of the world today is in fact an increased annual range of temperatures and conditions; this means in particular that third world human populations, many living in what are already marginal environments, will face ever more difficult situations. The current pattern of human-induced climate change is unlike anything we have seen before, and is disproportionately affecting areas whose inhabitants do not have the technology required to deal with it.'