This story begins 620. 000 years, when the human species began to populate some valleys of sub-Saharan Africa.
According to what was believed until now, at that time the cycles in which the Earth froze (the glaciations) and the periods in which the ice retreated marked the fate of our species.
In fact, these glacial and interglacial periods were thought to have been an essential part of human evolution.
Now, an international team of scientists claims to have found something different: they believe that, in reality, prehistoric weather patterns similar to those currently caused by El Niño were primarily responsible for causing environmental change “crucial” for human evolution.
Research, recently published in the journal Proceedings of the National Academy of Sciences , points out that these prehistoric weather patterns had more significant effects in sub-Saharan Africa than glacial-interglacial cycles.
Research
Although it was known that the Climate change was responsible for driving human evolution in Africa, the real nature of that change and its effects are not fully understood.
Previously, scientists knew that glacial and interglacial periods had an effect notable in the patterns of climate change in various areas of the world.
For this reason, they considered that they had also been responsible for the climatic variations that took place in Africa in the crucial period of the evolution of the humans less than a million years ago.
Experts assumed that ecosystem changes driven by such glacial cycles had triggered the evolution and spread of the first human species.
But the team led by Stefanie Kaboth-Bahr, from the Universi Potsdam’s dad, and other experts from the Max Planck Society in Germany, found something different.
The team of scientists set out to create an in-depth spatial image of where and when wet or dry conditions existed throughout the African continent.
For this, they incorporated 34 Africa-wide climate data files covering the latest 620 .000 years.
The result was an oscillation between periods of droughts and rains very similar to the one that currently causes El Niño (there is no evidence that the current pattern of this phenomenon is the same that affected that area thousands of years ago) .
El Niño is a phenomenon or event of climatic origin related to lime Entanglement of the eastern equatorial Pacific that, in its most intense manifestations, causes havoc in the intertropical and equatorial zone due to intense rains, mainly affecting the Pacific coastal region of South America.
” We were surprised to find an east-west climatic ‘swirl’, very similar to the pattern produced by El Niño weather phenomena, which today profoundly influence the distribution of rainfall in Africa, ”said Kaboth-Bahr.
The findings
From these findings, the study authors inferred that the main driver of this climate change was the impact of the tropical Pacific Ocean on the so-called “Walker Circulation”, a convection belt that runs along the equator and affects the aridity and rainfall of the tropics.
The data they found show that the periods of rain and Droughts changed between the west and east of the African continent on time scales of approximately 100. 11 years.
Each of these variations was accompanied by significant changes in the flora and fauna.
“This alternation between dry and wet periods seems have governed the dispersal and evolution of vegetation and mammals in East and West Africa “, says the lead author of the study.
” It is likely that the resulting environmental mosaic has been a critical component of human evolution and also of early demography “, he added.
The researchers point out that although oscillations in climate were not the only factor that drove the evolution of the first humans, the new findings offer a new image of the close relationship between the origin of the first humans and environmental changes.
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