Its probable climate change caused the migration of humans out of Africa

An article published in Nature explains why is it possible climate change caused the peopling of the world. 

Scientists continue to debate on which caused the Homo Sapiens to spread outside Africa so long after they first appeared approximately 150,000 to 200,000 years ago. Now a paper on Nature by Timmermann and Friedrich has developed a model that shows how climate change could have caused this migration.

Migrations into the eastern Mediterranean and the Arabian peninsula occurred around 1200,000 to 90,000 years ago, but further displacement to south Asia happened 50,000 years ago, to Europe 45,000 years ago, into north Asia 25,000 years ago and into the Americas about 15,000 years ago.

The role of climate change has been long debated  but all hypothesis agree climate affects resource richness and could drive human dispersal. These events could've been large volcanic eruptions, glacial Heinrich events (ice sheets collapse), orbital monsoonal-rainfall changes and sea level fluctuations.

Their modelling included ocean-atmosphere-vegetation model that changes as it shows variations in orbital insolation, carbon dioxide levels, glacial ice and sea levels over the past 125,000 years. They compared this with the available palaeoclimate and palaeoceanographic data to ensure their results were reasonable.

For example, today the Sahara and Arabian deserts are an effective barrier for species migration but in the past water conditions in the region allowed migration paths out of Africa and were vegetates, resource rich corridors. This happened during three time windows and supports the idea of environmental change drawing humans way form Africa.

The main discrepancy in their results is their suggestion of southern Europe experiencing a low density wave 80,000 years ago which is more than 35,000 years earlier than the generally accepted evidence.

Another example in Nature Education shows how  climate change has changed population dynamics more recently. Between 12,000- to 5,000 years ago the Sahara was a vegetated region with wooded grasslands, lakes and rivers. It was a place where cultural interaction happened up until 5,000 years ago when the monsoon rains weakened and retreated. Archeological records show there was a massive and rapid depopulation of the north of Africa at the same time  as the Sahara desert was established.

Climate change can shape life and it can be considered as one of the reasons why the early humans left Africa.

Prepared by 

LatinAmerican Post | Maria Andrea Marquez

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