LONDON — A significant cooling event more than a million years ago may have cause early humans in southern Europe to go extinct. An international team of researchers discovered extreme glacial conditions previously undetected 1.1 million years ago dramatically altered the European climate. This harsh cold likely surpassed the conditions that these archaic humans could endure, resulting in the depletion of human populations across the continent.
The most ancient human remains found in Europe come from Iberia, pointing to the idea that early humans might have migrated there from southwest Asia roughly 1.4 million years ago. Back then, the European climate was mainly characterized by warmth and ample rainfall, with occasional, mild cold phases. Until this recent discovery, the prevailing assumption was that once early humans settled in Europe, they were resilient enough to withstand multiple climate shifts and could adapt to the intensifying cold after 900,000 years ago.
“Our discovery of an extreme glacial cooling event around 1.1 million years ago challenges the idea of continuous early human occupation of Europe,” says study senior author Chronis Tzedakis, a professor of geography at University College London, in a university release.
To unveil this climatic mystery, paleoclimate experts from multiple institutions meticulously examined marine micro-organisms’ chemical makeup and analyzed pollen within a deep-sea sediment core taken from the coast of Portugal. Their findings unveiled abrupt climate changes leading up to this severe glacial cooling, during which the ocean surface temperatures near Lisbon plunged below six degrees Celsius, and semi-deserts started expanding across adjacent landmasses.
“To our surprise, we found that this cooling at 1.1 million years ago was comparable to some of the most severe events of recent ice ages,” notes study lead author Dr. Vasiliki Margari, from University College London.
The study emphasized that human tribes might have been ill-equipped to tackle such drastic temperature drops without tools like fire, efficient clothing, or proper shelter.
To better understand how this climate change might have affected early human habitats, researchers utilized a supercomputer called Aleph to simulate the environment during this ancient cold snap. Coupling these simulations with existing archaeological and fossil records, they created a model predicting the feasibility of human habitation during that time.
“The results showed that 1.1 million years ago climate around the Mediterranean became too hostile for archaic humans,” says Axel Timmermann, professor at the IBS Center for Climate Physics at Pusan National University.
These findings combined with the absence of human remains and stone tools for the subsequent 200,000 years suggest a considerable gap in human presence in Europe.
“According to this scenario, Europe may have been recolonized around 900,000 years ago by more resilient humans with evolutionary or behavioral changes that allowed survival in the increasing intensity of glacial conditions,” says study co-author Chris Stringer, professor at the Natural History Museum in London.
The study is published in the journal Science.
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