As the Earth’s climate became wetter, ancient humans were able to migrate wider, suggests a new scientific model

Neanderthal skull

Scientists superimposed archaeological discoveries from six human species, including Homo sapiens, Neanderthals, and Homo heidelbergensis.Halamka / Getty Images

Before human activity, the Earth’s climate changed, changing climates shaped where and how ancient humans lived. A scientific model published Wednesday in the journal Nature reveals that human migration over the last 2 million years was shaped by changes in the Earth’s motion.

Using a powerful South Korean supercomputer, ALEPH created a team of scientists from South Korea and Europe a detailed simulation of the planet’s climate history dating back to the Pleistocene era. The model, which looks at 41,000-year-old cyclical patterns, incorporates climatic changes in response to small twists and turns in the Earth’s orbit.

Astronomical forces, such as an inclination in the Earth’s axis and small shifts in the shape of the Earth’s orbit around the sun, affected the levels of solar radiation that the planet received, causing rises and falls in temperature and precipitation levels. It took more than six months for the powerful supercomputer to chew the numbers and produced the longest comprehensive climate model simulation to date.

Researchers then mapped sites where more than 3,200 archeological discoveries of ancient fossils and artifacts from our ancestors and relatives in the Homo genus have been found, to identify the habitats where each species was able to thrive.

“Although different groups of archaic humans preferred different climatic environments, their habitats all responded to climate change caused by astronomical changes in the Earth’s axis’ meandering, inclination and orbital eccentricity with time scales from 21,000 to 400,000 years,” says Axel Timmermann, a climate physicist. at Pusan ​​National University in South Korea, who led the study, said in a statement.

The research team noticed trends emerging from the data. For example, they discovered that about 700,000 years ago, a hominin species – Homo heidelbergensis, believed to be the latest common ancestor of modern humans and Neanderthals – began to expand from their traditional range because our planet’s elliptical orbit created wetter , more habitable climatic conditions, making it easier to migrate. Simulations also indicate that modern human species, Homo sapiens, may have emerged as a result of droughts in southern Africa and Eurasia, which forced our early ancestors to adapt to hot, dry areas about 300,000 years ago.

Preferred habitats for Homo sapiens (purple shade, left), Homo heidelbergensis (red shade, middle), Homo neanderthalensis (blue shade, right) calculated from the new simulation.

Preferred habitats for Homo sapiens (purple shade, left), Homo heidelbergensis (red shade, middle), Homo neanderthalensis (blue shade, right) calculated from the new simulation.Department of Basic Sciences

Yet the role of climate in human evolution is still a much debated idea. Gaps in the archaeological data mean it is difficult to directly link the emergence of an early human species to a climate event, Tyler Faith, a paleontologist at the University of Utah who was not involved in the study, told Nature. “If the solution to the mystery of climate change and human development could be addressed in a paper, it would have been done 40 years ago.”

Other studies have looked at the link between climate change and human development. An influential theory by paleoanthropologist Rick Potts, who was not involved in the new climate model, suggests that climate fluctuations, which started about 400,000 years ago in East Africa, resulted in Homo sapiens being more adaptable to unpredictable changing environments, according to Science News.

In addition, there are limits to the hypothetical computer models used in the study, according to Michael Petraglia of the Max Planck Institute. Petraglia was not involved in the study, but is the author of a comment on the results: “The habitat suitability models are therefore a welcome scientific tool, but they are only models,” he said, adding, “We have a lot of work on earth, do not recycle only fossils and archeology, but reconstruct the environments in which hominins were found. “

For Timmerman and his team, the new, controversial findings contribute to our understanding of early human movement and evolution. “The global collection of skulls and tools is not randomly distributed in time,” Timmermann told Nature, adding, “It follows a pattern.”

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