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http://www.sciencemag.org/news/2018...s-nearly-catastrophic-period-human-prehistory
These clay pots were used to store meat, and researchers found relatively well preserved animal fat residue soaked into the porous, unglazed sherds. Extreme drought brought on by the 8.2-kiloyear event would have frizzled feed crops and grazing lands, and cooler winters would have increased animals’ food requirements. The combined effect would have been leaner, thirstier livestock, and their fat may have recorded chemical echoes of that dietary stress, the researchers reasoned.
The team used a technique known as gas chromatography–mass spectrometry to identify elemental variants known as isotopes. When the researchers looked at the fat deposits’ hydrogen isotopes, something interesting jumped out: In sherds dating to about 8200 years ago—and only those sherds—the ratio of the isotope deuterium, or heavy hydrogen, rose by about 9% in relation to other hydrogen isotopes from the samples. Previous research on the region’s climate and plant chemistry has shown that lower precipitation rates correlate with higher ratios of heavy hydrogen, which the livestock would have consumed as they grazed during the drought.
The isotopic signature was thus likely caused by the 8.2-kiloyear event, the researchers report today in the Proceedings of the National Academy of Sciences, the first direct archaeological evidence of this phenomenon. By analyzing other fat-soaked pot sherds from sites around the world, the team adds, scientists will for the first time be able to accurately recreate climate conditions for other ancient societies.
These clay pots were used to store meat, and researchers found relatively well preserved animal fat residue soaked into the porous, unglazed sherds. Extreme drought brought on by the 8.2-kiloyear event would have frizzled feed crops and grazing lands, and cooler winters would have increased animals’ food requirements. The combined effect would have been leaner, thirstier livestock, and their fat may have recorded chemical echoes of that dietary stress, the researchers reasoned.
The team used a technique known as gas chromatography–mass spectrometry to identify elemental variants known as isotopes. When the researchers looked at the fat deposits’ hydrogen isotopes, something interesting jumped out: In sherds dating to about 8200 years ago—and only those sherds—the ratio of the isotope deuterium, or heavy hydrogen, rose by about 9% in relation to other hydrogen isotopes from the samples. Previous research on the region’s climate and plant chemistry has shown that lower precipitation rates correlate with higher ratios of heavy hydrogen, which the livestock would have consumed as they grazed during the drought.
The isotopic signature was thus likely caused by the 8.2-kiloyear event, the researchers report today in the Proceedings of the National Academy of Sciences, the first direct archaeological evidence of this phenomenon. By analyzing other fat-soaked pot sherds from sites around the world, the team adds, scientists will for the first time be able to accurately recreate climate conditions for other ancient societies.