Unearthing Early Agriculture: Advances in Archaeological Science
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Our understanding of early agriculture derives mostly from the material remains of food – seeds, other plant remains and animal bones. Archaeologists traditionally document these finds from excavated sites and use them to track dates and distribution of different people and practices. Over the past several decades, though, practitioners have become more skilled at spotting the earliest signatures of domestication, relying on cutting-edge advances in chemistry, biology, imaging and computer science.
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Archaeologists have greatly improved their capacity to trace the evolution of crops, thanks to advances in our capacity to recover minute plant remains – from silica microfossils to minute attachment scars of cereals, where the seeds attach to the rest of the plant. Along with early crops, agricultural weeds and storage pests such as mice and weevils also appeared. Increasingly, we can identify a broader biotic community that emerged around the first villages and spread with agriculture. For example, weeds that originated in the Fertile Crescent alongside early wheat and barley crops also show up in the earliest agricultural communities in places such as Germany and Pakistan.
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Collections of animal bones provide evidence of how herded creatures changed physically through the process of domestication. Butchering marks on bones can help reconstruct culling strategies. From the ages and sizes of animals, archaeologists can deduce the populations of herds in terms of age and sex ratios, all of which reveals how herding differed from hunting. Herding systems themselves also vary, with some focused only on producing meat, and others on milk and wool too.
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Measurements of bones and seeds have made great strides with technologies such as geometric morphometrics – complex mathematical shape analysis that allows for a more nuanced understanding of how varieties evolved and moved between regions. Biomolecular methods have also multiplied. The recovery of amino acid profiles from fragmented animal bones, for example, has allowed us to discern which animals they came from, even when they’re too degraded for visual identification. The increasingly sophisticated use and analysis of ancient DNA now allows researchers to track the development and distribution of domesticated animals and crops in great detail.
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Archaeologists have also used mass spectrometry, a technique involving gas ions, to pinpoint which species were cooked together based on the presence of biomolecules such as lipids. Stable isotopes of carbon and nitrogen from animal bones and seeds give insight into where and how plants and animals were managed – allowing us to more fully sketch out ancient food-webs from soil conditions to human consumption. Strontium isotopes in human and animal bones, meanwhile, allow us to identify migrations across a single organism’s lifetime, revealing more and earlier long-distance interconnections than previously imagined. Radiocarbon dating was already possible in the 1950s – but recent improvements that have reduced sample sizes and error margins allow us to build fine-grained chronologies and directly date individual crops. With all these fresh data, it’s now possible to tell a much richer, more diverse story about the gradual evolutions and dispersals of early agriculture.
