(ORDO NEWS) — The course of human evolution over the past 2 million years has been determined by habitat changes associated with astronomically driven climate change, scientists suggest in a new study.
Using unprecedented supercomputer simulations of the Earth’s climate during the Pleistocene era, the researchers found that changes in variables such as rainfall and temperature were related to how various hominin species, including Homo sapiens, settled or roamed over many centuries of prehistoric human history.
“Even if different groups of archaic people preferred different climatic conditions, all of their habitats responded to climate shifts caused by astronomical changes in the Earth’s axial oscillation, inclination and eccentricity of the orbit,” says climate physicist Axel Timmermann from Busan National University in South Korea.
The results obtained lend considerable weight to the argument that prehistoric episodes of climate change contributed to the evolutionary development of the genus Homo, a hypothesis long proposed but difficult to prove due to the lack of reliable climate data coinciding in time with the discovery of archaic humans in the fossil state.
“One of the most notable problems is that terrestrial records of habitat information – such as those obtained from sedimentary rock outcrops and Paleo leukic drill cores – are often limited in the time frame of available data,” explains archaeologist Michael Petraglia of the Max Planck Institute for Research. history of mankind in Germany, who did not participate in the study, but is the author of a commentary on the results.
To sidestep this issue, Timmermann and his team modeled changes in Earth’s environmental conditions over a period of 2 million years by incorporating astronomical climate shifts driven by Earth’s movement, known as Milankovitch cycles.
Simulations on a South Korean supercomputer called ALEPH took more than six months to create the longest-running integrated climate model to date.
The researchers then compared the findings with the documented presence of several hominin species in fossils – including Homo erectus, H. heidelbergensis, and H. neanderthalensis, among others – and covering more than 3,000 geochronologically restricted hominin fossils and related materials.
The results tell a complex story about how different groups of hominins settled across the Earth over time, but they also suggest that these expansions (and contrasting periods of residence in the same place) were associated with climatic features that influence such factors, like the suitability of temperature and the availability of food.
“Our study confirms that climate has played a fundamental role in the evolution of the genus Homo,” says Timmermann.
“We are who we are because we have been able to adapt over the millennia to slow climate change in the past.”
As an example, the researchers suggest that climate stress in southern Africa may have led to the emergence of H. sapiens while H. heidelbergensis went extinct. Beyond suggesting that climate data played a role in human evolution, the study goes even further, arguing that shifts in human adaptation cannot be fully explained without recourse to a broader understanding of climate factors influencing ecosystems.
“To understand the evolution of hominins during the Pleistocene, it is necessary to take into account the full spatial and temporal complexity of the climate signal and the corresponding habitat suitability,” the researchers write.
Experimental testing of such ideas will come from new field studies, Petraglia said, scrutinizing fossils to uncover traces of paleoenvironmental information that we haven’t yet uncovered.
“We still have much to learn about the evolutionary consequences of climate variability over the past 2 million years,” he writes.
“This study provides an opportunity to test a range of theories about how climate and habitat changes have affected the distribution, diversification, and dispersal of hominin species.”
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