How humans of yesteryear evolved due to climate change, according to science

For decades, science suspected that humanity evolved hand in hand with the climate changes of yesteryear. Now, a study published by an international team of scientists showed that those estimates were true. After analyzing fossil remains and archaeological artifacts, the experts managed to generate a computer simulation that covered the last 2 million years of Earth's climate history. In this model they were able to see how archaic humans lived.

In order to analyze this evolution from a climate, anthropological and ecological point of view, scientists at the Institute of Basic Sciences in Daejeon, South Korea, used a supercomputer called Aleph, one of the fastest in the country. After operating non-stop for more than 6 months, the researchers managed to finalize the most extensive comprehensive climate model yet.

The mechanism for understanding this situation linked periods and places where humans lived, based on archaeological records. In this way, scientists were able to relate what environmental conditions were preferred by the different groups of hominins and how they adapted to different food resources. The groups analyzed were: Homo sapiens, Homo neanderthalensis, Homo heidelbergensis (African and Eurasian populations), Homo erectus and African Homo (Homo ergaster and Homo habilis).

“Although different groups of archaic humans preferred different climatic environments, all of their habitats responded to climate 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,” said Axel Timmermann , leading author of the study published in the journal Nature.

Likewise, the director of the IBS Center for Climate Physics (ICCP) at Pusan National University, South Korea, noted that “this result implies that for at least the last 500,000 years the real sequence of past climate change, including glacial cycles, played a central role in the determination of where the different groups of hominins lived and where their remains have been found”.

Pasquale Raia, professor at the Università di Napoli Federico II (Italy) and who provided the study, together with his research team, with human fossil data and archaeological artifacts, stated that the next step was to analyze “whether the habitats of different human species overlap in space and time”, since the areas of contact between these groups of the past “provide crucial information on possible successions and mixtures of species”.

From the areas where different human evolutions were contacted, the experts made a family tree of hominids. In this sense, scientists managed to determine that “Neanderthals and probably Denisovans were derived from the Eurasian 'clade' of Homo heidelbergensis some 500-400 thousand years ago”, while the origin of “Homo sapiens dates back to southern Africa and to populations of late Homo heidelbergensis, about 300,000 years old”.

Jiaoyang Ruan, co-author of the study and postdoctoral fellow at the IBS Center for Climate Physics, said: “Our climate-based reconstruction of hominid lineages is quite similar to recent estimates obtained from genetic data or analysis of morphological differences in the human fossils, which increases our confidence in the results.”

“When we looked at the data from the five major groups of hominins, we discovered an interesting pattern. The first African hominids aged between 2 and 1 million years old preferred stable climatic conditions, being restricted to relatively narrow habitable corridors. After a major climate transition, some 800,000 years ago, a group known under the general term Homo heidelbergensis adapted to a much wider range of available food resources and were able to become global travelers. They reached remote regions of Europe and East Asia,” explained Elke Zeller, co-author of the study and doctoral student at Pusan National University.

For his part, Kyung-Sook Yun, a researcher at the IBS Center for Climate Physics, warned that this simulation “generated 500 Terabytes of data, enough to fill several hundred hard drives”, since “it is the first continuous simulation with a state-of-the-art climate model covering the Earth's environmental history of the last 2 million years, and represents climate responses to increasing and decreasing ice sheets, and to changes in greenhouse gas concentrations in the past.”

“Our study clearly illustrates the value of well-validated climate models in addressing fundamental questions about our human origins,” said Christoph Zollikofer, co-author of the study and professor at the University of Zurich (Switzerland); while Timmermann stressed that this research indicated that “ climate played a key role in the evolution of our Homo genre. We are what we are because we have managed to adapt for millennia to slow changes in the past climate.”

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