How ancient DNA may help in understanding the origin and spread of agriculture

The origin and spread of agriculture have been central questions in archaeology for the last 75 years and are increasingly being addressed by a multidisciplinary approach involving biologists, ecologists, geographers and anthropologists as well as archaeologists. Molecular genetics has the potential to make an important contribution, especially by enabling the number of times that a crop or animal was domesticated to be determined. Molecular genetics can also assign approximate dates to domestication events, identify the wild progenitor of a domesticate, and provide new forms of evidence relevant to agricultural spread. With wheat, molecular genetical studies of modern plants have suggested that einkorn was domesticated just once but that emmer might have been domesticated more than once. Ancient DNA studies of animal remains have benefited from progress made with equivalent analyses of human bones, and with plant material there have been clear demonstrations of DNA preservation in desiccated seeds. Charred remains have also been shown to contain ancient DNA but this finding is unexpected in view of the high temperatures to which these seeds have supposedly been exposed. Ancient DNA studies of wheat remains have been used in taxonomic identification and in assessment of the possible bread–making quality of the wheat grown at an Early Bronze Age site in Greece.