A recent study reveals that tomato plants in the Galapagos Islands are undergoing 'reverse evolution,' a rare phenomenon where they are reverting to ancestral traits. This discovery provides insights into the adaptability of life and opens new possibilities for genetic engineering in agriculture.
The research, published in *Nature Communications* in June 2025 by scientists from the University of California, Riverside, and the Weizmann Institute of Science, focused on two wild tomato species, *Solanum cheesmaniae* and *Solanum galapagense*. These plants are descendants of South American tomatoes. The study found that on younger, volcanically active islands, the tomatoes are producing alkaloids, bitter compounds that act as natural pesticides, similar to those found in eggplants.
The key difference lies in the stereochemistry of the alkaloids. Although the 'ancient' and 'modern' alkaloids are made of the same atoms, their three-dimensional arrangement differs, altering their biological behavior. Researchers identified the enzyme responsible for assembling the alkaloids. They discovered that only four amino acid changes in this enzyme were needed to revert its function, allowing the plants to synthesize the 'prehistoric' compounds. The geographical distribution of this phenomenon suggests an environmental cause, with the harsh conditions of the western islands favoring the resurgence of these defensive mechanisms.
This research challenges the classical view that once a trait is lost, it's unlikely to reappear through the same genetic pathway. The study demonstrates that 'reverse evolution' is possible and can occur precisely and consistently. This finding not only rewrites the understanding of plant evolution but also opens doors for genetic engineering, potentially leading to crops that are more pest-resistant, safer for consumption, or even have medicinal properties. It underscores that evolution is not a linear progression but a complex interplay where looking back can sometimes mean moving forward. The tomato, a globally consumed food, is a prime example of this fascinating process.