• Marine mollusc shells reveal how prehist

    From ScienceDaily@1:317/3 to All on Mon Apr 25 22:30:44 2022
    Marine mollusc shells reveal how prehistoric humans adapted to intense
    climate change

    Date:
    April 25, 2022
    Source:
    Universitat Autonoma de Barcelona
    Summary:
    A study reveals the impact and consequences of the '8.2 ka event',
    the largest abrupt climate change of the Holocene, for prehistoric
    foragers and marine ecology in Atlantic Europe.



    FULL STORY ==========================================================================
    A new multidisciplinary study involving ICTA-UAB researcher Asier Garci'a- Esca'rzaga reveals the impact and consequences of the '8.2 ka event',
    the largest abrupt climate change of the Holocene, for prehistoric
    foragers and marine ecology in Atlantic Europe.


    ========================================================================== Current global climatic warming is having, and will continue to have, widespread consequences for human history, in the same way that
    environmental fluctuations had significant consequences for human
    populations in the past.

    The so-called '8.2 ka event' has been identified as the largest and
    most abrupt climatic event of the past 11,700 years, caused by cool
    meltwater from North American lakes flooding into the North Atlantic
    and stopping ocean circulation systems. The cooling and drying effects
    of this event have been documented around the world, including along the Atlantic coast of Europe. Nevertheless, the sweeping impacts of the 8.2
    ka (kilo annum i.e., thousand years ago) event on different environments
    and human societies are often assumed rather than proven.

    The journalScientific Reports has published a paper led by Asier Garci'a Esca'rzaga, current researcher from the Institute of Environmental
    Science and Technology (ICTA-UAB) and the Department of Prehistory of the Universitat Auto`noma de Barcelona, together with Igor Gutie'rrez Zugasti,
    from the Universidad de Cantabria (UC). The study was coordinated from
    the Universidad de La Rioja (UR) and the Max Planck Institute (Germany) alongside members of other academic centres (Max Planck Institute,
    University of Burgos, Universidad Complutense de Madrid and University
    of Faro).

    The study applies a multidisciplinary toolkit of archaeomalacological
    studies and stable oxygen isotope analyses to shell remains recovered
    from the shell midden site of the El Mazo cave (Asturias, N Spain). With
    a long stratigraphic sequence of 1,500 years, El Mazo is a unique context
    along the European Atlantic coast, with especially high chronological resolution of each archaeological layer.

    The results obtained by these scientists allowed them to determine
    that colder seawater temperatures, deduced from stable oxygen isotope
    values measured on marine shells, led to changes in the availability
    of different shellfish species. For instance, one of the most commonly
    consumed species, the warm- adapted species P. lineatus, decreased during
    the 8.2 ka event, while populations of cold-adapted P. vulgata, another commonly exploited species, increased. Intriguingly, the warm-adapted
    limpet P. depressa also increased during this cool period, owing to a
    higher resistance to cold temperatures than other warm-water species.

    Their results also revealed an increase in the intensification of
    mollusc exploitation by humans, as indicated by a decrease in average
    mollusc size and evidence for increased harvesting in more dangerous
    coastal areas. The authors argued that this occurred because of human demographic growth in these Atlantic coastal settings which acted as
    refugia during this cold event, encouraging populations to move there
    from further inland. Nevertheless, populations around El Mazo managed to
    avoid over exploiting their coastal resources, as average mollusc size
    very rarely decreased below 20mm, the minimum size specified by modern regulations to guarantee long-term species survival.

    "Our results suggest an ongoing application of local marine ecological knowledge by some of the last foragers in western Europe, despite major
    changes to climate and demography" says Asier Garci'a-Esca'rzaga lead
    author of the current study.

    The resolution provided by the combination of taxonomic, geochemical and chronological analysis of molluscs from archaeological sites has major implications for other studies seeking to determine the significance of
    climate change on marine environments, and can provide detailed clues
    to the magnitude and nature of future climate changes and their impacts
    on human societies.


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


    ========================================================================== Journal Reference:
    1. Asier Garci'a-Esca'rzaga, Igor Gutie'rrez-Zugasti, Ana
    B. Mari'n-Arroyo,
    Ricardo Fernandes, Sara Nu'n~ez de la Fuente, David Cuenca-Solana,
    Eneko Iriarte, Carlos Simo~es, Javier Marti'n-Chivelet,
    Manuel R. Gonza'lez- Morales, Patrick Roberts. Human forager
    response to abrupt climate change at 8.2 ka on the Atlantic
    coast of Europe. Scientific Reports, 2022; 12 (1) DOI:
    10.1038/s41598-022-10135-w ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220425085732.htm

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