Over the past five million years, the Earth has transitioned from the warmer, wetter climate of the Pliocene (5.3 to 2.6 million years ago) to the cooler, drier climate of the Pleistocene (2.6 to 0.01 million years ago). of years). Now, thanks to a new study published in the journal Nature , it appears that the distribution of ancient humans over the past two million years was strongly influenced by Earth’s climate.
Thus, while Homo sapiens tolerated dry desert landscapes better at that time in history, Neanderthals preferred the Mediterranean climate. Regarding Homo erectus, it seems that it managed to adapt to a wide range of climatic environments that included tropical forests and semi-deserts.
Controversy in human evolution
The key point of this aspect is where exactly our species evolved in Africa. Among the conclusions of this research, it stands out that Homo sapiens arose in a single region in the south of the continent about 300,000 years ago.
The impact of climate change on human evolution has been on the table for a long time, but has been difficult to prove due to the paucity of climate records near human fossil sites.
To reach their verdict, a team of researchers from South Korea and Europe ran a computer simulation (using the Aleph supercomputer) of Earth’s climate history two million years ago and combined it with discoveries of human tools and bones. old. So, based on how the timing of ancient climatic variations coincided with the comings and goings of different fossil Homo species, the researchers generated a novel and controversial scheme of human evolution.
“Although different groups of archaic humans preferred different climatic environments, all of their habitats responded to climatic changes caused by astronomical changes in the wobble, tilt, and orbital eccentricity of the Earth’s axis with time scales ranging from 21 to 400,000 years,” says Axel Timmermann, lead author of the study and director of the IBS Center for Climate Physics (ICCP) at Pusan National University in South Korea.
hominin family tree
The migrations coincided with survival-enhancing warmer climate changes that occur every 20,000 to 100,000 years due to variations in Earth’s orbit and tilt that alter the amount of sunlight reaching the planet.
“This result implies that, for at least the past 500,000 years, the actual sequence of past climate change, including glacial cycles, played a central role in determining where different groups of hominins lived and where their remains have been found.” , exposes Timmermann.
Previous fossil evidence indicates that H. erectus spread as far east as Asia and Java. Timmermann’s climate simulations suggest that H. erectus , as well as H. heidelbergensis and H. sapiens , adapted to increasingly diverse habitats during long voyages. Those migrations stimulated brain growth and cultural innovations that “may have turned all three species into the global wanderers they were ,” he says.
In computer simulations, Homo sapiens, in particular, would have been particularly good at adapting to hotter, drier areas like northeastern Africa and the Arabian Peninsula.
It is the first study to link archaeological evidence with long-range climate modeling to reconstruct a history of early human movement and evolution.
“Our study documents that climate played a fundamental role in the evolution of our genus Homo. We are what we are because we have managed to adapt over millennia to slow changes in past climate,” concludes Timmermann.
Referencia: A. Timmermann et al. Climate effects on archaic human habitats and species successions. Nature. Published online April 13, 2022. doi: 10.1038/s41586-022-04600-9.