DNA from an underwater archaeological site off the coast of England suggests that wheat made its way to the region about 2,000 years before humans started farming it there. This discovery implies that Britain's hunter-gatherers traded with nearby farmers for the cereal grain long before they adopted agriculture.
The research sheds light on the Mesolithic-to-Neolithic transition, during which farmers migrating from east to west replaced hunter-gatherers throughout Europe. This transition has been the subject of much debate, with some researchers arguing that westward-bound farmers displaced Britain's hunter-gatherers rapidly and others suggesting a more gradual adoption of farming in the area.
New wheat DNA discoveries show that the grain was traded 2,000 years before it was farmed in Britain. | University of Warwick
Robin Allaby from the University of Warwick and colleagues from across the United Kingdom analyzed sediment cores from Bouldnor Cliff, a submarine site located off the Isle of Wight, to further examine this transition. Their results are published in the 27 February issue of Science.
"There are two viewpoints about how farming became established in Britain," explained Allaby. "The first is that farming took hold in Britain very quickly, instigated by an immigrant wave of Neolithic people. The alternative is that there was a slow establishment of farming involving a much more complex process, which is not completely understood yet. Our findings definitely support this latter viewpoint, with Mesolithic people playing an active role that has not previously been appreciated."
Allaby and his team isolated sedimentary ancient DNA, or sedaDNA, from Bouldnor Cliff estimated to be 8,000 years old. They reconstructed changes in the plant and animal communities that were present at the site then — before it was submerged — and identified DNA sequences that matched Near Eastern wheat strains. However, there was no evidence of wheat's cultivation nor any trace of its pollen.
"The environment [of Bouldnor Cliff] is a constant 4 degrees Celsius, in effect making it 'Nature's Fridge,'" said Allaby. "Consequently, the ancient DNA we found was actually in considerably better condition than that found in remains on land of the same age."
This pristine preservation of Bouldnor Cliff combined with the researchers' sedaDNA approach allowed for a more detailed look into the past than fossils could provide.
"Along with the wheat, we saw that this was a wooded, oak landscape with shrubs and grasses, canids — dogs or wolves — auroch, deer, grouse, and rodents," Allaby continued. "We see quite a lot of detail, which gives us a picture of the landscape and the components of a Mesolithic diet."
And since researchers generally agree that agriculture took hold in Britain about 6,000 years ago, these new findings suggest that hunter-gatherers in northwest Europe had developed social networks with migrating farmers and traded for wheat at least 2,000 years prior.
To Allaby, the big question now is why there was such a long delay in adopting the technology. "If they knew about the products of farming, why was it another 2,000 years before the practice was taken up in Britain?" he mused.