Blute Blog

A research article by Cagan et. al. on “Somatic Mutation Rates” and a cover story on it titled “Life Speed” were published in Nature on April 21. Some organisms have short, fast life cycles and tend to be small, others have longer, slower life cycles and tend to be large – think mice and men. A previous study of animals in zoos had found that the latter do not suffer from cancer any more than the former. The general phenomenon was once called “Peto’s paradox”. Cagan et. al. found in the particular case studied (gut epithelial cells in 16 species) that those in long-lived animals mutate much more slowly than do those in short-lived species. The only thing surprising to me is that anyone should find such results surprising! That could only come from viewing mutations from the perspective of physical rather than biological science. Rates per unit clock time should be similar from that perspective. But from a biological perspective, why should mutation rates not scale with all other life history traits – morphological, physiological, behavioural etc? They mostly do indeed as this research shows. The biological fact is, that like other pace of life characteristics, they have evolved. Does that mean they are adaptive? Possibly but not necessarily. Even in terms of the conventional synthetic theory of evolution, there are causes of evolution beyond natural selection – mutation, migration, drift etc.