Galápagos Wild Tomatoes Exhibit Rare Case of Reverse Evolution

In an unprecedented biological phenomenon, wild tomato plants on the volcanic islands of the Galápagos have been observed to exhibit traits reminiscent of their ancient ancestors, challenging conventional understanding of evolutionary processes. Researchers from the University of California, Riverside (UC Riverside) have documented this unusual occurrence, which they refer to as 'reverse evolution'. This significant finding raises questions about the adaptability of species in response to environmental pressures.

The study, led by Dr. Adam Jozwiak, a molecular biochemist at UC Riverside, was published in the journal Nature Communications on June 29, 2025. The research team collected over 30 samples of wild tomatoes from various islands, noting a distinct difference in chemical production between plants on older, stable eastern islands and those on the younger, harsher western islands. The western tomatoes have started producing alkaloids—bitter chemicals typically used for defense—that resemble those found in ancient tomato species as well as in their eggplant relatives, rather than the modern varieties known today.

Dr. Jozwiak explained that a slight alteration in the enzyme chemistry, specifically four amino acid changes in one enzyme, led to this remarkable shift. This modification altered the tomato's ability to synthesize alkaloids, reverting to a structure akin to that of its ancestors. The implications of this discovery extend beyond botany, suggesting potential avenues for biotechnological advancements, including the development of pest-resistant crops and new medicinal compounds.

The environmental context of the Galápagos Islands appears to play a crucial role in this phenomenon. The researchers posit that the harsher conditions on the western islands may compel the plants to revert to these ancient defensive mechanisms as a survival strategy. 'It could be that the ancestral molecule provides better defense in the harsher western conditions,' said Dr. Jozwiak.

This case of reverse evolution is not entirely unprecedented, yet it is notably rare and well-documented. Instances of organisms regaining lost traits are typically viewed with skepticism in the evolutionary biology community. However, the clear genetic and chemical evidence presented by the UC Riverside team supports their claims. 'Some people don’t believe in this,' noted Dr. Jozwiak, 'but the genetic and chemical evidence points to a return to an ancestral state. The mechanism is there. It happened.'

Moreover, the research prompts broader reflections on evolution's flexibility. As Dr. Jozwiak suggested, if environmental conditions were to change significantly, similar reverse evolutionary processes could potentially occur in other species, including humans, albeit over a much longer timeline.

The implications of these findings are profound, suggesting that traits once considered lost may merely be dormant, awaiting the right ecological conditions to resurface. This study represents a significant step toward understanding the complexities of evolutionary biology and the potential for nature to adapt in unexpected ways. As the research progresses, it may illuminate pathways for manipulating biological processes for agricultural and medicinal purposes, thereby reshaping our approach to biodiversity and conservation.