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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