Privileged Planet: plate tectonics join Asia and Africa (Introduction)

by David Turell , Monday, April 21, 2025, 18:20 (10 hours, 49 minutes ago) @ David Turell

Which influences migrations:

https://phys.org/news/2025-04-earth-mantle-ancient-ancestors-elephants.html

"In a paper published in Nature Reviews Earth & Environment, an international team of researchers investigated the formation of a large land bridge that connected Asia and Africa 20 million years ago, through what is now the Arabian Peninsula and Anatolia.

***

"This gradual uplift of land enabled the early ancestors of animals such as giraffes, elephants, rhinoceroses, cheetahs, and even humans, to roam between Africa and Asia. The appearance of the land ended a 75-million-year-long isolation of Africa from other continents.

***

"The story begins 50–60 million years ago, when a slab of rock sliding into Earth's mantle created a "conveyor belt" for hot rocks to boil up in an underground plume that reached the surface some 30 million years later. This convective activity in the mantle, coupled with the collision of tectonic plates, created an uplift in land that contributed to closing the ancient Tethys Sea, splitting it into what is now the Mediterranean and Arabian Seas, and created a landmass that bridged Asia and Africa for the first time.

"The study's lead author Eivind Straume analyzed the wide-ranging consequences of this geologic activity while he was a postdoctoral fellow at the Jackson School. He said the appearance of the land bridge and animal evolution go hand in hand.

"'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 Straume, who is now a postdoctoral fellow at NORCE Norwegian Research Center and The Bjerknes Center for Climate Research. "Without the plume, you could argue that the continental collision would have been different."

"In this case, timing is everything. If it had been an additional million years before Africa and Asia were connected, the animals that made their way into and out of Africa could have been on a different evolutionary path. That includes the ancestors of today's humans.

"Several million years before the land bridge had completely closed, the primate ancestors of humans came to Africa from Asia. While those primates ended up going extinct in Asia, their lineages diversified in Africa. Then when the land bridge fully emerged, these primates re-colonized Asia."

Comment: contingent events strongly effected migrations and evolution. It is a two-way street: life transforms the Earth and a changing Earth transforms life.