The Origin of Peanuts: New Genetic Study Reveals How Humans Cultivated the Food

Where do peanuts come from? Scientists have now traced the roots of the peanut crop back to Bolivia with the help of a "living relic."

The peanut grown by farmers today is the result of hybridization between two wild species. The hybrid was actually cultivated by ancient inhabitants of South America and then, with selection, was transformed into today's crop plant.

Comparisons of the DNA sequences of one of the wild species and the cultivated peanut showed that they are almost exactly the same. In fact, they are 99.96 percent identical, which is almost an unprecedented similarity.

"It's almost as if we had traveled back in time and sampled the same plant that gave rise to cultivated peanuts from the gardens of these ancient people," said David Bertioli, one of the researchers, in a news release.

Because its ancestors were two different species, today's peanut carries two separate genomes. Their high similarity, though, means that they are very difficult to map out separately when sequencing the cultivated peanut genome. As a first step, the scientists built their models using the two wild, ancestral peanut species collected by botanists in the wooded foothills of the Andes in Bolivia and Argentina decades ago.

So what did they find? It turns out that one of the ancestral species' seeds had been transported by humans about 100,000 years ago. They realized this after finding only one location where the two strains grew together; usually, the two are found hundreds of miles apart.

"Everything fit," said Bertioli. "It's the only place where A and B genome species have ever been found growing close together. The region is right next to the region where, even today, the most primitive types of cultivated peanut are grown, and the date is right in the time frame that plant domestication was happening in South America."

The findings are published in the journal Nature Genetics.

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