Scientists Watch Fungi Evolve in Real Time, Thanks to a Marriage Proposal in a Cheese Cave A new study pinpoints a disruption in a gene that made a beloved blue cheese’s rind go from green to white Sara Hashemi - Daily Correspondent October 10, 2025 3:27 p.m. The mold growing on batches of Bayley Hazen Blue cheese changed from green to white between 2016 and the present day. Benjamin Wolfe In 2016, Benjamin Wolfe, a microbiome scientist at Tufts University, was scheming. He’d convinced his former advisor, Rachel Dutton, to drive with him to Jasper Hill Farm in Greensboro, Vermont, to collect samples of a cheese called Bayley Hazen Blue. But the visit was about more than the sweet, creamy dairy product: It was a ruse so that Dutton’s boyfriend could propose at the farm, where they had first met. The surprise proposal went ahead as planned, and the biologist got his samples—scrapes from the cheese wheels’ rinds. He stored them in a freezer in his lab for years. “I’m notorious for not throwing samples away just in case we might need them,” he says in a statement. The cheese collected in 2016 was coated in a “very avocado-limey-green color,” Wolfe recalls to Elizabeth Preston at the New York Times. But a few years later, when graduate student Nicolas Louw went to pick up new samples at the farm, the rinds of the newer cheeses were completely white. The recipe hadn’t changed. Neither had the caves where the farm ages its blue cheese. Perhaps the mold had changed instead, the scientists surmised. “This was really exciting, because we thought it could be an example of evolution happening right before our eyes,” Wolfe says in the statement. “Microbes evolve. We know that from antibiotic resistance evolution [and] pathogen evolution, but we don’t usually see it happening at a specific place over time in a natural setting.” Did you know? A fungus among us According to a report from the American Academy of Microbiology, “Cheese is one of the few foods we eat that contains extraordinarily high numbers of living, metabolizing microbes.” Fungi are just the start—cheeses gain their flavors and textures from yeast (a type of fungus) and other microbes, like bacteria. Genetic analysis revealed the cheese rinds’ color change happened because of a disruption in ALB1, a gene involved in the production of melanin, which is known for its role in protection from ultraviolet (UV) radiation. In humans, melanin produces eye color as well as hair and skin pigmentation. In cheeses, melanin affects the appearance of the rind. It makes sense that fungi growing in a cave would shed a gene designed to produce melanin as it evolved, since it doesn’t need protection from ultraviolet light, Louw explains in the statement. The phenomenon, known as “relaxed selection,” is common in species that experience the removal of an environmental stressor. “By breaking that pathway and going from green to white, the fungi are essentially saving energy to invest in other things for survival and growth,” Louw says. The findings, published in the journal Current Biology last month, are a “perfect example of evolution in action,” Sam O’Donnell, a fungal genomicist at the University of Wisconsin–Madison who wasn’t involved in the work, tells the New York Times. Understanding how the Penicillium solitum fungi in the cheese evolve can also have other benefits. In the statement, the researchers say the work could be used to help prevent lung infections caused by other molds in the same family—or even help bolster global food security. “Around 20 percent of staple crops are lost pre-harvest due to fungal rot, and an additional 20 percent are lost to fungi post-harvest,” Louw says in the statement. “That includes the moldy bread in your pantry and rotting fruit on market shelves.” Being able to manage mold could help solve that issue. Next, Wolfe and his team will explore making new types of cheese with different tastes and textures based on their findings. They’ve already collaborated with the farm on a fresh brie with the white mold and found it tastes “nuttier and less funky,” Wolfe says in the statement. The cheeses will continue to be refined on the farm. “Seeing wild molds evolve right before our eyes over a period of a few years helps us think that we can develop a robust domestication process, to create new genetic diversity and tap into that for cheesemaking,” Wolfe adds. As for Dutton? She said yes. “We are very grateful to [her husband] for his elaborate marriage proposal,” the researchers note in the acknowledgments section of their paper. “It is because of his marriage proposal that the 2016 samples were collected.” Get the latest stories in your inbox every weekday.

A new study pinpoints a disruption in a gene that made a beloved blue cheese's rind go from green to white