Guac is extra, but should it be? Texas A&M anthropologist shows the resilience of ancient avocados

Today’s avocado industry, a multi-billion-dollar global enterprise, relies primarily on a single variety: the Hass avocado. This monoculture approach poses significant risks, as genetically identical plants are more vulnerable to disease and climate change.

Dr. Heather B. Thakar, an assistant professor in the Department of Anthropology at Texas A&M University, is leading groundbreaking research at El Gigante Rockshelter in Honduras, uncovering the deep history of avocado domestication. Her work, recently documented in an article accepted by Proceedings of the National Academy of Sciences, provides remarkable insights into how humans have shaped the evolution of one of today’s most economically significant crops.

“Our work with El Gigante’s avocado remains offers valuable information about resilience and adaptation in the face of climate change,” Thakar said. “Much of the genetic diversity of ancient avocados still exists in wild populations in Mexico and Central America. By developing new avocado varieties through seed selection from both modern domesticated plants and wild populations, we may have a better chance of adapting to these changing conditions than relying on cloning alone.”

A Rare Archaeological Opportunity

El Gigante Rockshelter, located in the highlands of western Honduras, has yielded astonishingly well-preserved plant fossils — unusual in the humid tropics where organic materials typically decay rapidly.

"It’s a truly incredible preservation of plant fossils and abundance of avocado remains in a tropical region where plants generally do not preserve well," Thakar said.

For over 11,000 years, this site has been home to preserved avocado remains, allowing researchers to track how humans influenced the fruit’s development over millennia.

“Avocados are an amazing food source for humans, rich in healthy fats and nutrients that are essential to us,” Thakar said. “But they originally evolved as a food source for ancient megafauna like giant sloths (gomphotheres) and mammoths that lived in the Americas during the last ice age.”

When these megafaunas disappeared, humans filled the ecological gap, managing and cultivating avocado trees in ways that enhanced their value as a food source.

“Through traditional forest management practices, people were selecting bigger and thicker-skinned avocados,” Thakar said. “And by 7,500 years ago, indigenous farmers were able to produce nutritious fruits that were more productive and easier to transport.”

Evidence Of Early Avocado Farming

The research team relied on hundreds of radiocarbon dates, many taken directly from avocado pits and rinds, to establish a detailed timeline of human occupation and avocado management at El Gigante. Measurements of avocado seeds and rinds demonstrated that early Hondurans were selecting for larger and more robust fruits over thousands of years, culminating in domesticated varieties by around 2,000 years ago. This finding is particularly significant because it reveals that avocados were farmed in Honduras even before maize, beans or squash — the cornerstone crops of Mesoamerican agriculture.

El Gigante’s extraordinary collection of preserved plant remains has also provided insights into the domestication of other crops, such as squash and maize.

“I am actively working on a publication that details the arrival of maize and the 4,500 years of diversification and improvement of this globally important crop,” Thakar said.

A Globally Significant Archaeological Site

Recognized as one of the most important archaeological sites discovered in Central America in the last 40 years, El Gigante is on the tentative list for UNESCO World Heritage status. Thakar and her team are collaborating with the Honduran government to document and protect this unique site.

“All of the research that we have undertaken is used in support of El Gigante's recent nomination as a UNESCO World Heritage site; we continue to provide research support, documentation and expert commentary throughout this process,” she said.

Although El Gigante has been spared from looting due to its difficult-to-access entrance—requiring a three- to four-meter climb—there have been modern disturbances including occasional overnight stays by hunters and adventurous visitors. Nevertheless, archaeologists have been able to preserve its deepest stratigraphic layers, ensuring that invaluable historical evidence remains intact.

The Excitement Of Discovery

For Thakar, the thrill of discovery is what drives her work.

“We have the opportunity to learn so much about the many ways that humans have dealt with change in the past,” she said. “When there are no written records, archaeology steps in, contributing to the cumulative knowledge about the past that can be deployed to inform modern crises.”

An anthropological archaeologist, Thakar’s research bridges the humanities and sciences, integrating innovative methodologies such as radiocarbon dating, stable isotope analysis and morphometrics to analyze ancient plant remains. Her work is not limited to Honduras—she is also a principal investigator on projects exploring plant domestication and cultural knowledge transmission in southern Mexico, Belize and Nicaragua.

Understanding The Deep History Of Agriculture

Thakar hopes that her research will help people appreciate the long and complex process of plant domestication.

“The vast majority of food consumed today is a product of domestication,” she said. “But domestication was not an event. It was a lengthy process that produced an incredible diversity of plants that are extraordinarily adapted to local environments. By studying domestication, we can recover ancient varieties and cultural knowledge that has helped humans become the incredibly successful species that we are... information that can be used to improve our crops today and ensure our continued survival into the future.”

 By Jordan Fox, Texas A&M University College of Arts and Sciences

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