Ancient avocados found in a cave could save the world's crop.

There is just one type of avocado that feeds the world's appetite: the creamy Hass. Production has been streamlined into a multibillion-dollar enterprise due to this genetic similarity. However, uniform orchards can suddenly collapse when confronted with a new pest, virus, or heat wave; thus, it also invites calamity.

Experts from Texas A&M University have taken a different route, travelling 11,000 years into the past to a rock shelter in Honduras whose burned ancient avocado pits document the crop's birth and provide hints for a more resilient future.

Fossils of avocados in a cave

A natural vault, El Gigante is situated high in the western Honduran highlands. Plant remains that would often decompose in the wet tropics have been preserved in its arid interior.

According to co-author Heather B. Thakar, an assistant professor in Texas A&M's Department of Anthropology, "it's a truly incredible preservation of plant fossils and an abundance of avocado remains in a tropical region where plants generally do not preserve well."

Undisturbed, layer after layer of seeds, rinds, and other botanical remnants form a chronological record of human consumption—and human impact on native plants—dating back to the last ice age.

Giants were outlived by avocados.

The scientists believe that the original purpose of avocados was to attract large browsers like mammoths and gomphotheres. According to Thakar, avocados are a fantastic food source for people because they are full of minerals and good fats.

"However, during the last ice age, they first evolved as a food source for ancient megafauna such as mammoths and giant sloths (gomphotheres) that inhabited the Americas."

Humans filled the ecological gap left by the extinction of those creatures. Early foragers preferentially care for wild trees at El Gigante, producing saplings with larger seeds and meatier fruit.

Farming for thousands of years

To create an incredibly fine-grained timeline, the scientists radiocarbon-dated hundreds of pits and rinds. Measurements showed a consistent increase in size over the centuries, with rinds becoming thicker and seeds becoming larger.

According to Thakar, "people were choosing bigger and thicker-skinned avocados through traditional forest management practices."

Fruit durability and size suggest that gardeners were able to harvest and ship avocados across greater distances about 7,500 years ago. Approximately 2,000 years ago, full domestication occurred.

As a result, the development of avocados in Honduras predates that of maize, beans, or squash—crops that would eventually rule Mesoamerican agriculture.

Lessons learnt from the past for upcoming crops

"We learnt a lot about adaptability and resilience in the face of climate change from our work with El Gigante's avocado remains," Thakar stated. Ancient farmers sowed seeds, maintaining genetic diversity, as opposed to contemporary orchardists who graft identical Hass cuttings.

According to Thakar, "wild populations in Mexico and Central America still possess a large portion of the genetic diversity of ancient avocados."

"Instead of depending solely on cloning, we might have a better chance of adapting to these changing conditions by creating new avocado varieties through seed selection from both contemporary domesticated plants and wild populations."

Adding characteristics like disease resistance or drought tolerance to commercial cattle could protect future harvests from environmental shocks.

An ancient avocado cave gains international recognition

El Gigante is valued by both local people and scientists for its scientific significance in addition to its cultural significance. The shelter has been nominated by Honduras for UNESCO World Heritage classification, and Thakar's team provides supporting data.

"El Gigante's recent nomination as a UNESCO World Heritage site is supported by all of the research that we have conducted," she stated.

Even though looters have been discouraged by the site's hard three-meter ascent, hunters and campers do occasionally venture inside, necessitating immediate formal security.

An agricultural cave

El Gigante also contains early evidence of the domestication of maize and squash. A book detailing the introduction of maize and the 4,500 years of development and diversification of this significant crop for the world is currently in the works of Thakar.

Thakar's techniques, which include 3-D morphometrics, stable-isotope chemistry, and radiocarbon dating, combine cultural anthropology and hard science. She maps the long-standing relationship between humans and plants in Mexico, Belize, and Nicaragua using this toolbox.

Modern lessons from ancient farming

According to Thakar, "the great majority of the food consumed today is a product of domestication."

Modern breeders can be guided by an understanding of that lengthy process. Without the use of greenhouses or genetic engineering, ancient farmers were able to develop crops that were perfectly suited to the soils and temperatures of their regions, such as avocados.

Alleles lost in today's simplified variations might be found by unearthing those lost lineages. "We can recover ancient varieties and cultural knowledge that have helped humans become the incredibly successful species that we are by studying domestication," Thakar suggested.

"It's knowledge that can help us enhance our crops now and guarantee our survival for years to come." The avocado's journey from a cliffside in Honduras to orchards throughout the world demonstrates that diversity fosters agricultural resilience and that sometimes looking back is the greatest way to go forward.