Bayley Hazen Blue
“Show me an example of witnessed evolution!” is one of the stock demands from creationists in online debates. But it’s a trick request. No sooner is an example given than they hurriedly shift the goalposts, redefining evolution into a childish caricature. Instead of the real scientific process, they demand to see a cow turn into a whale overnight, or a mouse suddenly grow wings—some grotesque parody of “macro-evolution” that no biologist has ever claimed happens. Ironically, if such nonsense did occur, it would actually falsify the theory of evolution rather than confirm it.
This intellectual dishonesty is the lifeblood of creationist rhetoric. Their arguments only work by preying on scientific illiteracy in their audience, peddling strawmen and false definitions to cover the absence of any evidence for their own claims.
Meanwhile, science continues as it always has, with evolution properly defined as a change in allele frequency in a population’s gene pool over time. And right on cue, another clear demonstration has just been published in Current Biology.
The researchers studied the fungus Penicillium solitum, which is used to ripen cheese, by following its population over eight years in the controlled cave environment of Jasper Hill Farm. By comparing samples collected in 2016 with those taken more recently, they were able to track both visible and genetic changes in the mould over time.
What they found was striking. The rind colour, once a leafy green, had shifted to a chalky white. Genetic analysis showed this was due to repeated mutations in a pigment-producing gene called alb1, which is responsible for melanin production. In the dark, cave-like conditions, melanin offered no advantage, so natural selection favoured lineages that conserved energy by not producing it. The loss of pigment arose independently several times, through different mutations—including both point mutations and the disruption of the gene by mobile DNA elements.
This is evolution at its most direct: heritable changes in the genetic make-up of a population, producing visible differences in response to environmental conditions. It illustrates a well-known principle called relaxed selection—when a trait is no longer useful, natural selection no longer preserves it, and the trait may fade away. In this case, the shift also altered the appearance and sensory qualities of the cheese, underlining how evolutionary change can have immediate, practical consequences.
