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Dr John Stewart in the New Scientist

19 September 2012

Dr John Stewart, a senior lecturer in Palaeoecology and Environmental Change at Bournemouth University, has contributed to an article in the New Scientist which looks at climate change and the evolution of man.

The article suggests that the reason Homo sapiens moved from Africa to colonise other parts of the world, like Europe and Asia, was because of changes to the climate.

Homo sapiens evolved in Africa around 200,000 years ago, but only left the continent around 70,000 years ago, and researchers at the University of Cambridge have been modelling the climate and environmental conditions at the time to see whether these contributed to the population spread around the planet.

These models allowed them to calculate changes in vegetation in different regions, and estimate of the amount of food available there.

They accurately reproduced the pattern and timings of human expansion out of Africa and across the continents – which suggests that climate and food supply are key elements in explaining how humans spread worldwide.

Dr Stewart told the New Scientist that there are some “inconsistencies” with the modelling, but that “the results are still remarkably good.”

He has also proposed that earlier bouts of climate change helped the many species of early humans to evolve, by forcing them into isolated refuges where they evolved separately.