Frequency of the adaptive allele in several human populations (from the 1000 Genomes dataset). Colors and letters represent different populations in the dataset, and the pie charts reflect the proportion of individuals in those populations who have the variant TRPM8 allele. FELIX M. KEY, MPI-EVA MULTIMEDIA DEPARTMENT AND COLLEAGUESA human genetic variant in a gene involved in sensing cold temperatures became more common when early humans migrated out of Africa into colder climates between 20,000 and 30,000 years ago, a study published today (May 3) in PLOS Genetics shows. The advantage conferred by this variant isn’t definitively known, but the researchers suspect that it influences the gene’s expression levels, which in turn affect the degree of cold sensation. The observed pattern of positive selection strongly indicates that the allele was beneficial, but that benefit had a tradeoff—bringing with it a higher risk of getting migraines.
“This paper is the latest in a series of papers showing that humans really have adapted to different environments after some of our ancestors migrated out of Africa,” explains evolutionary geneticist Rasmus Nieslen of the University of California, Berkeley, who was not involved in the study. “There are a number of adaptations associated with moving into an arctic climate, but none with as clear a connection to cold as this one,” he adds.
Selection is optimizing fitness. It doesn’t optimize health, it doesn’t optimize happiness, so sometimes things are pushed by selection and they have negative side effects. —Johns Hawks,
University of Wisconsin-Madison
Although studies have demonstrated some striking examples of recent human adaptation, for instance, warding off infectious diseases such as malaria or having ...
