Our ancestors suddenly disappeared. Now we know why
While global warming might be the bane of modern human existence, our ancestors were likely faced with a different kind of apocalypse.
A new study has found that Europe’s first humans were probably wiped out by an ‘extreme cooling event’ about 1.1 million years ago.
The species, Homo erectus, were ancestors of the Homo sapiens – people – of today.
Researchers suggest that the previously unknown dip in temperature coincides with what’s known about human habitation of Europe.
Fossils and stone tools show that Homo erectus arrived in Europe from Asia between 1.8 million and 1.4 million years ago but they seem to have died out from the continent about 1.1 million years ago.
The next evidence of prehistoric humans in Europe is seen around 900,000 years ago with the arrival of Homo antecessor from Africa or Asia.
A team of researchers, led by Axel Timmermann of the Institute for Basic Science in South Korea, reconstructed the climate of Europe during this time using climate models.
They found that the average temperature in Europe dropped by about 5C over a period of just a few decades.
The researchers found evidence of the sudden cooling in cores of marine sediment sampled from the ocean floor off the coast of Portugal. For instance, the water temperature near Lisbon dropped from 21C on average to around 6C.
This sudden and dramatic cooling would have made it harder for Homo erectus to find food, as fewer plants and the animals would have survived the extreme climate change.
In addition, Homo erectus themselves weren’t suited for the cold. They lacked sufficient fat insulation and the means to make fire, effective clothing, or shelters, according to the study.
‘This is a story of how climatic variability had profound effects on hominin populations in the past, with implications for all of humanity today who face extreme weather events and changes in ecosystems,’ said Michael Petraglia, a Paleoanthropologist, speaking to LiveScience.
Homo erectus is an extinct species of humans that lived in Africa, Asia, and Europe from about 2 million years ago to approximately 117,000 years ago. They were the first humans to leave Africa and are thought to have been the ancestors of later human species, such as Neanderthals and modern humans.
While the occurence of an Ice Age was known some 900,000 years ago, there was no hard evidence of an even earlier cold period about 1.1 million years ago.
The main reason for the cooling seems to have been Jupiter’s gravitational influence making the Earth’s orbit roughly circular around the Sun, a circumstance associated with other cooling phases in our planet’s climate. When the orbit is elliptical, as it is now, the Earth is closer to the Sun for longer periods.
The cooling period was also marked by a drop in the level of carbon dioxide in the Earth’s atmosphere, but it remains unclear if that was the cause of the cooling or a consequence of it.
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