In the high-elevation desert region of the Trans-Himalayas, most people farm for a living. In the 1980s, they largely transitioned from subsistence-based to market-oriented production of commercial crops, such as green peas (Pisum sativum L.), they could sell to other states in India.

For their own communities and monasteries, however, some farmers still cultivate foods with a 3,000-year legacy in the area, including barley (Hordeum vulgare) and a local variety of black peas that lacks a scientific name. Favored for nutrition and sustained energy, these black peas are an integral part of traditional recipes, such as soups and hot drinks. In a new study published Aug. 15 in Science Advances, Stanford researchers examined the genetic diversity, ecological resilience, and dietary value of the black peas for the first time.

"Black peas and barley are intimately tied to the cultural, religious, and social life in the Trans-Himalayan region. That they are also climate resilient is what makes them so exciting," said the study's lead author, Harman Jaggi, PhD '24. "One of our findings was what the local farmers knew all along - black peas are more ecologically resilient and have higher protein levels, as compared to the introduced cash crop green peas."

Scientists generally agree that peas, first grown around 10,000 years ago in the Fertile Crescent, have one domesticated and one wild species. But the new study, which provided the first whole genome sequencing data for the black peas, suggests that they form distinct genetic clusters, "highlighting a complex cultural and environmental selection over thousands of years," Jaggi said.

The research team examined whether, as compared to green peas, the black peas were better adapted to the local climate, especially as the region faces significantly decreased winter precipitation due to climate change.

Across sites at three different elevations and with varied watering treatments, black peas showed a higher probability of survival and more successful reproductive traits. This finding corroborated anecdotes from farmers, who said black peas are easier and less water intensive to grow than green peas.

The researchers also drew up a nutritional profile of black peas in collaboration with the Central Food Technological Research Institute in India. Compared to green peas, black peas are richer in protein - boasting 21% protein per 100 grams - and high in minerals like magnesium, calcium, and iron. The peas are also a significant source of fiber and vitamins C, B1, and B3.