Published on 06/08/2026

By Elton Alisson, from London  |  Agência FAPESP – What do the Amazon rainforest and Greenland have in common? According to Davi Moreno-Mateos, a University of Oxford professor, the answer lies in a rare scientific opportunity: the chance to observe ecosystems regenerating without human interference after centuries of occupation. For this reason, Moreno-Mateos chose the Amazon as the subject of a study that seeks to understand what happens when local populations abandon cultivated areas, allowing the forest to recover spontaneously.

“The Amazon is the perfect place to find that answer because there are so many areas in the forest that were abandoned long ago and have never been repopulated – something difficult to find in a world where the population is growing dramatically. After many years of research, the only place I found that was somewhat similar in that regard was Greenland,” the researcher said during FAPESP Week London, held June 2–4 in the British capital.

While Greenland features traces of Norse settlements abandoned between 650 and 1,050 years ago, the Amazon offers records on a much larger scale. Hidden beneath dense secondary vegetation are areas that appear to be primary forests but are, in fact, silent witnesses to pre-Columbian agriculture that shaped the landscape for millennia, Moreno-Mateos explained.

The soil is often characterized by terra preta (literally “black earth”), which is indicative of the fertility left behind by ancient human settlements. This serves as a historical record that allows us to determine when the region was occupied and when it was finally abandoned.

In these soils, some populations of Brazil nut trees (Bertholletia excelsa) have recovered over long periods without human intervention after indigenous peoples selected and dispersed their seeds for thousands of years, the researcher stated.

“The Brazil nut is a species that has undergone selection for at least 11,000 years, but once abandoned, it continues to exist with very little natural dispersal,” he said.

The cost of selection

The central hypothesis of the project is that the domestication of these plants by indigenous peoples, who prioritized characteristics such as fruit size, may have reduced their natural resilience.

“By selecting a species to produce larger fruits, its ability to adapt decreases, which is risky when facing droughts caused by climate change, for example,” he explained.

To verify whether the genome of the species changed after undergoing this type of selection, the team performed whole-genome sequencing to compare young trees (about 200 years old) with older ones (500 years or older), some of which can reach 50 meters in height.

Preliminary results indicate that, after being “released” from domestication following the disappearance of local human populations, the trees began to exhibit genetic changes suggesting a return to functions more closely linked to survival than to massive seed production – a phenomenon the group is now mapping in detail.

“We found changes in selection signatures between young and old trees. By relating the age of the site to the differences in their genomes, we observed that there were several clearly distinct populations,” said the researcher.

Occupation in waves

The integration of archaeology and ecology has revealed that Amazonian occupation occurred in “waves,” leaving a genetic legacy in the species that persists to this day. However, Moreno-Mateos’s final message is a warning about the fragility of biological time.

Although the Amazon is often described as a resilient system, the research indicates that an ecosystem’s recovery following agricultural abandonment occurs on timescales of hundreds to thousands of years, not decades. “When cutting down the forest without thinking about the consequences, we must remember that any action taken in two days with a bulldozer will take centuries for nature to repair,” he warned.

The study seeks to understand the past and identify populations of Brazil nut trees with greater resilience through their genetic code. “The goal is for these individuals to be able, in the future, to provide propagules [structures that detach from the plant to give rise to a new individual, such as seeds or buds] essential for forest restoration strategies on a warming planet, where the ability to adapt will mean the difference between survival and collapse for biomes,” Moreno-Mateos concluded.

More information about FAPESP Week London is available at fapesp.br/week/2026/london.

Source: https://agencia.fapesp.br/58330