Wild tomatoes on the Galápagos Islands are rewinding millions of years of evolution, according to a new study.
Scientists at the University of California, Riverside found that these tomatoes—descended from South American ancestors likely brought to the Pacific archipelago by birds—are producing a toxic molecular cocktail not seen in millions of years.
Biologists described this as a rare and striking case of “reverse evolution.”
Adam Jozwiak, a molecular biochemist at UC Riverside and lead author of the study, told Newsweek that while “de-evolution” makes for a striking headline, what we’re really seeing is evolution taking an unexpected turn, reverting to a state that existed millions of years ago.
Could something similar happen in humans? Jozwiak said in theory, yes.
“Humans, like all organisms, are subject to evolutionary forces,” Jozwiak explained.
“If environmental conditions shifted dramatically over long timescales, it’s possible that traits from our distant past could re-emerge, but whether that ever happens is highly uncertain. It’s speculative and would take millions of years, if at all.”
The key players in this evolutionary reversal are alkaloids—chemicals that serve as built-in deterrents against pests.
Most cultivated tomatoes produce one type of alkaloid structure, but these Galápagos tomatoes have shifted toward an older chemical form—an evolutionary echo from their distant past and similar to compounds found in eggplant.
Researchers pinpointed a single enzyme, known as GAME8, that plays a central role in forming these chemicals. Normally, GAME8 adds a chemical group in a specific three-dimensional shape (‘right-handed’ or ‘left-handed’).
Mutations in GAME8 among western island tomatoes altered just a few building blocks (amino acids), flipping the shape back to the ancestral form.
The research team confirmed this by inserting the modified enzyme into tobacco plants, which then produced the ancient-style alkaloid.
The chemical shift is not random. Eastern islands, which are older and more ecologically diverse, host tomatoes making modern alkaloids.
In contrast, the harsher environments on younger, western islands seem to favor the ancestral, eggplant-like chemicals. Researchers believe the older alkaloids may offer better defense under these tougher conditions.
Jozwiak told Newsweek that the tomato species studied were wild relatives located in the Galápagos and not included in the human diet, which means there are no direct health implications for humans.
“If similar changes occurred in cultivated tomatoes, it might affect how these toxins interact with our digestive system or gut microbiome, but that’s purely hypothetical,” he said. “For now, this discovery is important for what it tells us about evolution, not for any immediate impact on human health.”
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Reference
Jozwiak, A., Almaria, M., Cai, J., Panda, S., Price, H., Vunsh, R., Pliner, M., Meir, S., Rogachev, I., & Aharoni, A. (2025). Enzymatic twists evolved stereo-divergent alkaloids in the Solanaceae family. Nature Communications, 16(1), 5341. https://doi.org/10.1038/s41467-025-59290-4
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