Toxic Evolution

Abstract

When my daughter developed an infection that had begun streaking up her leg, my first thoughts were of methicillin-resistant Staphylococcus aureus, or MRSA. Although it was staph, fortunately it wasn’t MRSA, and the antibiotics she had been prescribed won out. But with antibiotic resistance on the rise, we can no longer assume that common bacterial infections will be conquered with a simple course of antibiotics. For too long we believed we could easily outwit bacteria with antibiotics, and we did for nearly half a century before realizing our folly. We have ignorantly underestimated life’s capacity for evolution. But there were early warnings. Back in 1945, when Alexander Fleming, father of modern antibiotics, won the Nobel Prize for discovering penicillin, he cautioned that inappropriate use of the antibiotic might have some unwelcome consequences:

Penicillin is to all intents and purposes non-poisonous so there is no need to worry about giving an overdose and poisoning the patient. There may be a danger, though, in underdosage. It is not difficult to make microbes resistant to penicillin in the laboratory by exposing them to concentrations not sufficient to kill them, and the same thing has occasionally happened in the body. The time may come when penicillin can be bought by anyone in the shops. Then there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant. … Moral: If you use penicillin, use enough.¹

It is likely that most toxic chemicals in the environment will affect evolutionary processes. … We predict that a new field, evolutionary toxicology, will emerge to address these issues.

John Bickham and Michael Smolen

Whereas it is true that evolution has clearly not rescued all species or populations from extinction, explorations of extinction probabilities based on the limitations of selection and response stand in stark contrast to a growing literature demonstrating that surprising amounts of adaptive evolution occurs in the wild and laboratory within a human life span.

Michael Kinnison and Nelson Hairston Jr.

In short, humans cause particularly dramatic changes in organisms— and these changes are probably often adaptive.

Andrew Hendry and colleagues