EARLIEST CROPS
Ancient hunter-gatherers began to systemically affect the evolution of crops around 10,000 years earlier than previously thought. Professor Robin Allaby of the University of Warwick has discovered that human crop gathering was so extensive, as long ago as the last Ice Age, that it started to have an effect on the evolution of rice, wheat and barley – triggering the process which turned these plants from wild to domesticated. In Tell Qaramel in northern Syria, the research demonstrates evidence of einkorn being affected up to 30,000 years ago, and rice has been shown to be affected more than 13,000 years ago in south, east and south-east Asia. Emmer wheat was affected 25,000 years ago in the southern
Levant – and barley in the same geographical region over 21,000 years ago.
The timeline of crop evolution in these areas was traced by analysing the evolving gene frequencies of excavated plant remains. Wild plants contain a gene that enables them to scatter their seeds widely. When a plant begins to be gathered on a large scale, human activity alters its evolution, changing this gene and causing the plant to retain its seeds instead of spreading them – thus adapting it to the human environment, and eventually agriculture.
Professor Allaby and his colleagues made calculations from archæobotanical remains of crops that contained ‘non-scattering’ genes and found that human gathering had already started to alter their evolution millennia before previously accepted dates. Crop plants adapted to domestication exponentially around 8,000 years ago, with the emergence of sickle farming technology, but selection changed over time. The study pinpoints the origins of the selective pressures leading to crop domestication much earlier, and in geological eras considered inhospitable to farming. Demonstrating that crops were being gathered to the extent of being pushed towards domestication up to 30,000 years ago proves the existence of dense populations of people at this time.
Professor Robin Allaby commented: “This study changes the nature of the debate about the origins of agriculture, showing that very long term natural processes seem to lead to domestication – putting us on a par with the natural world, where we have species like ants that have domesticated fungi, for instance.” phys.org/news, 23 Oct 2017.
• A group of hunter-gathers near China’s Yangtze River started to grow rice around 9,400 years ago, as shown from phytoliths unearthed at a site called Shangshan. Phytoliths are hard, microscopic pieces of silica made by plant cells for self-defence. Rice leaves have fan-shaped phytoliths and the specific patterns on those found here suggest these people were not just gathering rice, but actually cultivating it. Phytoliths in modern rice have more than nine fishscale decorations. The ancient phytoliths in Shangshan were a mix of different numbers of fish-scale decorations – as they got younger, the proportion with more than nine increased and became more like modern rice. This is evidence of rice’s gradual domestication, a process that was long and slow. theatlantic.com, 29 May 2017.