• Early human habitats linked to past clim

    From ScienceDaily@1:317/3 to All on Wed Apr 13 22:30:44 2022
    Early human habitats linked to past climate shifts

    Date:
    April 13, 2022
    Source:
    Institute for Basic Science
    Summary:
    A study provides clear evidence for a link between
    astronomically-driven climate change and human evolution.



    FULL STORY ==========================================================================
    A study published in Nature by an international team of scientists
    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,
    the team of experts in climate modeling, anthropology and ecology was
    able to determine under which environmental conditions archaic humans
    likely lived.

    The impact of climate change on human evolution has long been suspected,
    but has been difficult to demonstrate due to the paucity of climate
    records near human fossil-bearing sites. To bypass this problem, the team instead investigated what the climate in their 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 [1]. 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," said
    Axel Timmermann, lead author of the study and Director of the IBS Center
    for Climate Physics (ICCP) at Pusan National University in South Korea.

    To test the robustness of the link between climate and human habitats, the scientists repeated their analysis, but with ages of the fossils shuffled
    like a deck of cards. If the past evolution of climatic variables did not impact where and when humans lived, then both methods would result in the
    same habitats. However, the researchers found significant differences
    in the habitat patterns for the three most recent hominin groups (Homo
    sapiens, Homo neanderthalensis and Homo heidelbergensis) when using the shuffled and the realistic fossil ages. "This result implies that at least during the past 500 thousand years the real sequence of past climate
    change, including glacial cycles, played a central role in determining
    where different hominin groups lived and where their remains have been
    found," said Prof. Timmermann.

    "The next question we set out 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," said Prof. Pasquale Raia from the Universita` di Napoli
    Federico II, Naples, Italy, who 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 then derived a
    hominin family tree, according to which Neanderthals and likely Denisovans derived from the Eurasian clade of Homo heidelbergensisaround 500-400
    thousand years ago, whereas Homo sapiens' roots can be traced back to
    Southern African populations of late Homo heidelbergensisaround 300
    thousand years ago.

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



    ==========================================================================
    The new study was made possible by using one of South Korea's fastest supercomputers named Aleph. Located at the headquarters of the Institute
    for Basic Science in Daejeon, Aleph ran non-stop for over 6 months to
    complete the longest comprehensive climate model simulation to date. "The
    model generated 500 Terabytes of data, enough to fill up several hundred
    hard disks," said Dr.

    Kyung-Sook Yun, a researcher at the IBS Center for Climate Physics who conducted the experiments. "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," adds Dr. Yun.

    "So far, the paleoanthropological community has not utilized the
    full potential of such continuous paleoclimate model simulations. Our
    study clearly illustrates the value of well-validated climate models to
    address fundamental questions on our human origins," says Prof. Christoph Zollikofer from the University of Zurich, Switzerland and co-author of
    the study.

    Going beyond the question of early human habitats, and times and
    places of human species' origins, the research team further addressed
    how humans may have adapted to varying food resources over the past 2
    million years. "When we looked at the data for the five major hominin
    groups, we discovered an interesting pattern. Early African hominins
    around 2-1 million years ago preferred stable climatic conditions. This constrained them to relatively narrow habitable corridors. Following a
    major climatic transition about 800 thousand year 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," said Elke Zeller,
    PhD student at Pusan National University and co-author of the study.

    "Our study documents that climate played a fundamental role in the
    evolution of our genus Homo.We are who we are because we have managed to
    adapt over millennia to slow shifts in the past climate," says Prof. Axel Timmermann.

    [1]This study considers the following hominin species: Homo sapiens,
    Homo neanderthalensis, Homo heidelbergensis (including African and
    Eurasian populations), Homo erectus and early African Homo (including
    Homo ergaster and Homo habilis).

    Youtube link: https://youtu.be/MNJ-RnhBVkU

    ========================================================================== Story Source: Materials provided by Institute_for_Basic_Science. Note:
    Content may be edited for style and length.


    ========================================================================== Related Multimedia:
    * Map_showing_where_archaic_humans_likely_lived ========================================================================== Journal Reference:
    1. Axel Timmermann, Kyung-Sook Yun, Pasquale Raia, Jiaoyang Ruan,
    Alessandro
    Mondanaro, Elke Zeller, Christoph Zollikofer, Marcia Ponce de Leo'n,
    Danielle Lemmon, Matteo Willeit, Andrey Ganopolski. Climate effects
    on archaic human habitats and species successions. Nature, 2022;
    DOI: 10.1038/s41586-022-04600-9 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220413131147.htm

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