A study published in Nature provides clear evidence for a link between astronomically-driven climate change and human evolution. By combining the most extensive database of well-dated fossil remains and archeological artefacts with an unprecedented new supercomputer model simulating earth's climate history of the past 2 million years. A team of experts in climate modeling, anthropology and ecology was able to determine under which environmental conditions archaic humans likely lived.
Preferred habitats of Homo Sapiens and Homo heidelbergensis Homo neanderthalensis calculated from a new paleoclimate model simulation conducted at the IBS Center for Climate Physics and a compilation of fossil and archeological data. Lighter values indicate higher habitat suitability. The dates referinf into the estimated ages of the youngest and oldest fossils used in the study.
Preferred habitats of Homo Sapiens, Heidelbergensis and Homo Neanderthalensis calculated from a new paleoclimate model simulation conducted at the IBS Center for Climate Physics and a compilation of fossil and archeological data. Lighter values indicate higher habitat suitability. The dates refer to the estimated ages of the youngest and oldest fossils used in the study.
The impact of climate change on human evolution has long been suspected but has been difficult to demonstrate owing to the paucity of climate records near human fossil-bearing sites. To bypass this problem team instead investigated what the climate in their realistic computer simulation was like at the times and places humans lived. According to the archeological record this revealed the preferred environmental conditions of different groups of hominins. From there, the team looked for all the places and times those conditions occurred in the model, creating time-evolving maps of potential hominin habitats.
"Even though different groups of archaic humans preferred different climatic environments, their habitats all responded to climate shifts caused by astronomical changes in earth's axis wobble, tilt, and orbital eccentricity with timescales ranging from 21 to 400 thousand 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.
"The next question we wanted to address was whether the habitats of the different human species overlapped in space and time. Past contact zones provide crucial information on potential species successions and admixture," says Prof. Pasquale Raia from the Università di Napoli Federico II, Naples, Italy
Together with his research team compiled the dataset of human fossils and archeological artefacts used in this study. From the contact zone analysis, the researchers derived a hominin family tree according to which Neanderthals and likely Denisovans derived from the Eurasian clade of Homo heidelbergensis around 500-400 thousand years ago, whereas Homo sapiens' roots can be traced back to Southern African populations of late Homo heidelbergensis around 300 thousand years ago.
Analising results from the computated data
The new study was conducted using the ICCP/IBS computer Aleph, one of South Korea's fastest supercomputers. Located at the headquarters of IBS in Daejeon, Aleph computer ran non-stop for over 6 months to complete the longest comprehensive climate model simulation up to this date. It is the first continuous simulation with a state-of-the-art climate model that covers earth's environmental history of the last 2 million years, representing climate responses to the waxing and waning of ice-sheets. Changes in past greenhouse gas concentrations, as well as the marked transition in the frequency of glacial cycles around 1 million years ago.
Going beyond the question of early human habitats, and times and places of human species' origins, the research team further addressed how humans have adapted to varying food resources over the past 2 million years. When they studied the data for the five major hominin groups, they discovered an interesting pattern. Early African hominins around 1-2 million years ago preferred stable climatic conditions. This constrained them to relatively narrow habitable corridors. Following a major climatic transition about 800 thousand years ago, a group known under the umbrella term Homo Heidelbergensis adapted to a much wider range of available food resources, which enabled them to become global wanderers, reaching remote regions in Europe and eastern Asia.
Title of original paper: Climate effects on archaic human habitats and species successions
Journal: Nature, DOI: https://doi.org/10.1038/s41586-022-04600-9
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