With the help of funding from the European Research Council, Allaby and his colleagues examined cereal grains from archeological sites throughout the world and tested them for a genetic trait that makes grain seeds fall off the stem easily.
Wild cereal strains bear the trait. It makes it easier for them to spread their seeds and propagate. But domesticated cereal strains lack it, with good reason. Keeping the seeds on the steam makes it easier to cultivate. Otherwise, farmers would lose their crops before harvest.
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Scientists have long believed that people unwittingly domesticated grains by harvesting wild cereals.
The theory goes that people would have more easily harvested grain seeds that fell off the plant with less effort, leaving behind those with the mutation that kept the seeds on the plant for longer. Those remaining seeds would then eventually fall off, spreading strains containing the mutation. Natural selection would then result in the proliferation of strains we now know as domesticated grains.
The study didn’t challenge or confirm that theory. But the researchers found traces of the hardy seed mutation dating back far earlier than experts had discovered in the past. That lead them to conclude that domesticating wild grains took tens of thousands of years rather than over the course of a few millennia during the so-called “agricultural revolution.”
“It really looks natural,” said Allaby. “It really looks like a natural consequence of dense human populations in a certain ecology. There is no revolution.”
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But Allaby noted that samples of domesticated plants did spike around 8,000 years ago when people started using sickles to harvest their grains. He speculated that the new farming technology and denser human settlements led to an uptick in the pace of a process that had been occurring previously.
Interestingly, he added, the findings suggest that humankind’s domestication of grains might resemble the way ants and beetles domesticate fungi for food, fish farm algae, and other symbiotic relationships.
“It’s a natural process. Ants have domesticates. There are more than one example. It’s not an uncommon phenomenon,” said Allaby. “The human action in domestication really fits in that bucket, in that category of affecting the plants and animals around you.”