Kevin Wann had never eaten an avocado. Not once, in all the years he spent studying them. The researcher, who was working as a fellow at the Smithsonian's National Museum of Natural History, decided he wanted to see how far he could get through his dissertation on the fruit without ever tasting it. But that all changed when a farmer in Nicaragua offered him one during a tour of a local grove. Wann finally took a bite. And in doing so, he uncovered something surprising about the humble fruit that billions of people eat every year.
In a paper published July 22 in the journal Plants, People, Planet, Wann and his team revealed that avocados growing wild and in small farms across Nicaragua, Honduras, and southern Mexico carry unique genetic traits that do not exist in the commercial varieties found in grocery stores. These native avocados, grown by local farmers and gardeners for generations, look similar to the ones found in Florida or the Caribbean, but their DNA tells a different story.
The research suggests that around 5,000 years ago, people migrating north from South America carried avocado seeds with them. As these seeds were planted and spread through the humid lowlands of Central America, they mixed with local varieties, creating new types of avocados with genes that are entirely distinct from the Hass variety most people know today.
The Hass avocado, named after a mail carrier from California named Rudolph Hass who first grew it in the 1920s, now dominates the global market. More than 80 percent of the 11 million metric tons of avocados produced worldwide in 2024 came from this single variety. All Hass avocados are essentially clones of each other. Farmers grow them by taking a branch from one tree and attaching it to another, which produces fruit that is genetically identical. It is the avocado equivalent of photocopying a photocopy.
This uniformity is a problem. Because every Hass avocado tree is basically the same, they are all vulnerable to the same diseases, the same droughts, and the same floods. If a new avocado disease spreads around the world, it could wipe out most of the global harvest.
That is where the wild avocados of Central America come in. Wann and his colleagues collected leaves from dozens of avocado trees across southern Mexico, Nicaragua, and coastal Honduras. They spoke with local farmers and gardeners to learn how these traditional varieties have been cultivated for thousands of years. What they found was a rich diversity of avocado genetics that science had never fully documented before.
Logan Kistler, the Smithsonian curator who advised Wann on the research, said traditional farming practices have shaped these plants over millennia. "You cannot think about biodiversity without considering agriculture, because it is one of the most impactful ecological activities we do," Kistler said. The varieties grown by Central American farmers, known as landraces, have been honed by generations of selective planting, making them naturally suited to their local environments.
For the avocado industry, worth billions of dollars worldwide, this hidden diversity could be a lifeline. Scientists may one day be able to borrow genes from these wild Central American varieties to make commercial avocados more resistant to disease and climate change. The fruit on your plate tomorrow might owe a debt to a small grove in Nicaragua.