Sea mollusk shells reveal how prehistoric humans adapted to extreme climate change – Watts Up With That?
UNIVERSITAT AUTONOMA DE BARCELONA
Global climate warming is causing, and will continue to have, widespread consequences for human history, just as environmental changes have had dramatic consequences for species populations. people in the past. The so-called ‘8.2 ka event’ has been identified as the largest and most abrupt climate event of the past 11,700 years, caused by the influx of cool water from North American lakes into the North Atlantic Ocean and causes shut down ocean circulation systems. The event’s cooling and drying effects have been noted around the world, including along Europe’s Atlantic coast. However, the far-reaching effects of the 8.2 ka (kilo annum, i.e. thousands of years ago) event on various environments and human societies are often assumed rather than proven.
Journal Scientific reports published a paper by Asier García Escárzaga, current researcher from the Institute of Environmental Science and Technology (ICTA-UAB) and the Department of Prehistory of the Universidad Autònoma de Barcelona, together with Igor Gutiérrez Zugasti, from University of Cantabria (UC). The research was coordinated by the Universidad de La Rioja (UR) and the Max Planck Institute (Germany) along with members of other academic centers (Max Planck Institute, University of Burgos, Universidad Complutense de Madrid and University of Faro) ).
The study applies a multidisciplinary toolkit of archaeological studies and stable oxygen isotope analysis to seashell remains recovered from the central shell area of the El Mazo cave (Asturias, West Africa). Spain). With a stratigraphic sequence spanning 1,500 years, El Mazo is a unique setting along Europe’s Atlantic coast, with exceptionally high resolution of the chronology of each archaeological layer.
The results obtained by these scientists allowed them to determine that colder sea temperatures, inferred from stable oxygen isotope values measured on seashells, lead to variation in the availability of water. of different shellfish species. For example, one of the most commonly consumed species, the warm-adapted P. lineatus species, declined during the 8.2 ka event, while cold-adapted populations of P. vulgata, one species unusually exploited, increased again. Interestingly, the warm-adapted P. depressa limpet also increased during this cool period, due to its higher tolerance to cold temperatures than other warm-water species.
Their results also show an increase in the intensity of human krill exploitation, as demonstrated by a decrease in mean mollusk size, and evidence for increased fishing in more hazardous coastal regions. The authors argue that this is due to human demographic growth in these Atlantic coastal regions, which act as a shelter during this cold event, encouraging populations can move there from inland areas. However, populations around El Mazo have managed to avoid overexploitation of their coastal resources, as the average size of molluscs very rarely falls below 20mm, the minimum size being established. regulated by modern regulations to ensure the long-term survival of the species.
“Our results demonstrate the continued application of local marine ecological knowledge by some of the last foragers in Western Europe,” said Asier García-Escárzaga, lead author of the current study. despite major changes in climate and demographics.
The solution provided by a combination of taxonomic, geochemical and chronological analysis of molluscs from archaeological sites is of great significance to other studies aimed at determining the significance of variation. climate change on the marine environment and can provide detailed clues about the extent and nature of future climate change and their impact on human society.
JOURNEYS
Scientific reports
DOI
RESEARCH METHODS
Experimental study
RESEARCH SUBJECTS
Animals
ARTICLE TITLE
Human response to sudden climate change at 8.2 ka on Europe’s Atlantic coast
Here is the summary and the introduction
abstract
The cooling and drying associated with the so-called ‘8.2 ka event’ has long been hypothesized to have far-reaching effects on human society during the Early Holocene, including some hunter-gatherers of the last Mesolithic period in the Atlantic Ocean. However, detailed ‘in situ’ records that can be explored for broader climate change impacts on human-related environments are still lacking. Here, we reconstruct the sea surface temperature (SST) from the δ18O values measured on the young shells of Phorcus lineatus mined by Mesolithic groups living in the El Mazo cave (Spain) during the period. from 9 to 7.4 ka. The Bayesian model of 65 radiocarbon days, combined with this δ18O data, provides a high-resolution seasonal record of the SST, revealing that the colder SST during the 8.2 ka event led to these 8.2 ka events. changes in the availability of different shellfish species. The increased human exploitation of molluscs reflects demographic growth in these Atlantic coastal regions that act as a refuge during these cold times.
Introduce
Current global climate warming is and will continue to have widespread human consequences. Looking to the past, many climate and environmental changes have long been thought to have shaped human evolution and behavior1,2,3. The Holocene (11.7–0 ka cal BP) was a geological epoch characterized by relatively stable climatic conditions. However, that stability was disrupted by a series of abrupt climate changes, especially during the early Holocene 4. Of these, the ‘8.2 ka event’ was identified as the largest and most abrupt climate event during the Holocene5,6. Climate scientists suggest that this ‘event’ was the result of an outbreak of water ice from the Laurentide lakes in North America7. The influx of cold water into the Atlantic Ocean leads to a decrease in sea surface salinity and a decline in the Atlantic meridian upstream circulation (AMOC), leading to a decrease in sea surface temperature (SST) across the North Atlantic8. The cooling effect of this event was recorded in proxies from the Greenland ice core6 and throughout Europe5,9,10. Short and distinct periods of cooler or drier periods have also been recorded ~8.2 ka across the northern hemispheres 11,12,13 and south 11,12,14. However, as a well-established climate phenomenon now, the far-reaching effects of the ‘8.2 ka event’ on various environments are often still assumed rather than proven, and Local records of marine or terrestrial conditions available at an appropriate resolution are often lacking. Furthermore, while changes in temperature or precipitation associated with the ‘8.2 ka event’ are often well-defined, there are few paleontological proxies that can help to better understand the effects of the ‘8.2 ka event’. 8.2 ka’ condition for the seasonality of climatic conditions in different regions. of the world.
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