Activity In The Earth’s Mantle Was Responsible For Leading Our Ancient Ancestors Into Africa And Asia
The activity beneath the Earth’s surface is often undetectable to us, but it has the power to shape land masses and dictate climate patterns, ocean circulation, and even animal evolution.
Scientists believe that a plume of hot rocks that burst from Earth’s mantle millions of years ago could be a crucial part of human evolution.
An international team of researchers investigated the development of a large land bridge that connected Africa and Asia around 20 million years ago through what is now the Arabian Peninsula and Anatolia.
As the land gradually lifted up, the early ancestors of animals like elephants, giraffes, cheetahs, rhinoceroses, and even humans were able to roam between Africa and Asia. Before the appearance of the land, Africa had been isolated from other continents for 75 million years.
Around 50 to 60 million years ago, a slab of rock slid into the Earth’s mantle, creating a way for hot rocks to boil up in a plume that reached the surface about 30 million years later.
This activity in the mantle, along with the collision of tectonic plates, caused the land to lift up, which contributed to the closing of the ancient Tethys Sea.
It was split into what is now the Mediterranean and Arabian Seas, resulting in a landmass that bridged Africa and Asia for the first time. According to the research team, the appearance of the land bridge and animal evolution are linked.
“The shallow seaway closed several million years before it otherwise likely would have due to these specific processes—mantle convection and corresponding changes in dynamic topography,” said Eivind Straume, the lead author of the study and a postdoctoral fellow at NORCE Norwegian Research and The Bjerknes Center for Climate Research.
“Without the plume, you could argue that the continental collision would have been different.”
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Several million years before the land bridge closed completely, the primate ancestors of humans arrived in Africa from Asia.
Those primates ended up going extinct in Asia, but their lineages diverged in Africa. When the land bridge emerged fully, the primates re-colonized Asia.
The uplift of the Arabian Peninsula also had major impacts on ocean circulation and the Earth’s climate. The nearby ocean temperatures warmed, which expanded the seasonal temperature ranges and made a piece of land from North Africa to central Asia more dry and arid.
The researchers think that the formation of the land bridge was finally what pushed the Sahara into becoming a desert.
These changes also made the monsoon season stronger in Asia, leading to a wetter southeast Asia. Overall, the study shows how our planet changed and how life and tectonics are connected.
The details of the new study were published in the journal Nature Reviews Earth & Environment.
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