{UAH} Did climate change cause our ancestors to leave Africa? Maybe. But they also came back to Africa.
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Did climate change cause our ancestors to leave Africa? Sediment deposits reveal how bursts of rainfall may have driven evolution
- Researchers made discovery after analysing sediment from Oman
- These sediments provided a 160,000 year record of area's climate
- Deposits reveal our ancestors left Africa 75,000 to 130,000 years ago
- They did so in multiple phases as a result of rapid bursts of rainfall
- This contradicts theory they left all at once around 50,000 years ago
By Ellie Zolfagharifard For Dailymail.com
Published: 00:46 GMT, 20 February 2015 | Updated: 00:49 GMT, 20 February 2015
Human evolution was driven by short, rapid waves of climate change.
This is according to researchers studying cone-shaped deposits of sediment in southeast Arabia that provide a 160,000 year record of the area's climate.
The deposits reveal that our early human ancestors left Africa on a journey to southern Asia around 75,000 to 130,000 years ago, during multiple phases.
Human evolution may have been driven by short, rapid waves of climate change.This is according to researchers studying cone-shaped deposits of sediment from southeast Arabia that provide a 160,000 year record of the area's climate. Inset is photo ofthe exposed quarry site. A person circled for scale
The find contradicts another theory that claims human populations expanded rapidly from Africa to southern Asia via the coastlines of Arabia around 50,000 to 60,000 years ago.
The sediments reveal a period of increased rainfall, which scientists at Oxford University argue would have provided sufficient freshwater to support expanding populations.
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'The dispersal of early human populations out of Africa is dynamically linked with the changing climate and environmental conditions of Arabia,' said Professor Ash Parton at Oxford University.
'Although now arid, at times the vast Arabian deserts were transformed into landscapes littered with freshwater lakes and active river systems.
The sediments – also known as alluvial fans - were found along the Western Haja in Al Sibetah, Oman. Pictured is a stock image of alluvial fan deposits
'Such episodes of dramatically increased rainfall were the result of the intensification and northward displacement of the Indian Ocean Monsoon, which caused rainfall to reach across much of the Arabian Peninsula.'
The sediments – also known as alluvial fans - were found along the Western Haja in Al Sibetah, Oman.
A previous study by University College London argued that the waxing and waning of huge lakes in the East African Rift valley was linked to the brain expansion of early human species.
Professor Mark Maslin, co-author of the study, said at the time: 'It seems modern humans were born from climate change.
'They had to deal with rapid switching from famine to feast - and back again - which drove the appearance of new species with bigger brains and also pushed them out of East Africa into Eurasia and South Africa.'
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