Australasian Science: Australia's authority on science since 1938

Deselecting “Evolition”

By Simon Says

A report that whooping cough had evaded the current vaccine by mutating epitomises misconceptions about evolution.

It was a straight little story on ABC-TV about a new strain of whooping cough that is resistant to the current vaccine. “The bacteria has mutated to evade it,” the reporter said, committing a subtle error that has become common usage in popular treatments of evolutionary development, from David Attenborough down.

Whether it be animations of trilobitesque critters crawling out of the surf onto a virgin beach, or re-enactments of early hominids stepping down from trees and walking upright into a grassy African plain, the language of their explanations implies that these evolutionary breakthroughs were provoked by some kind of willful urge or even aspirational intent. Evolution is presented as “evolition”.

Not so. Whenever a whooping cough bacterium infects a suitable new host it can proliferate into billions of individuals. The more clones that are produced, the more will be expressed by the host into spaces shared with other potential hosts. Thus the bacterial lineage can be sustained.

The more it is sustained the more cloning occurs, so mutations become more likely. The more mutations, the more likely it is for novel strains to arise. More novel strains means more chances for this bacterial lineage to continue as antagonists occur in its environment, as each strain has a different chance of resisting any antagonist.

So it is that a strain of whooping cough resisted the antagonist vaccine. It didn’t “mutate to avoid it” – a mutation just happened to resist it.

As Charles Darwin put it in the first edition of On the Origin of Species: “A large number of individuals, by giving a better chance for the appearance within any given period of profitable variations, will compensate for a lesser amount of variability in each individual, and is, I believe, an extremely important element of success”.

Same for the first creatures to survive out of the sea, or the first hominids to walk upright. They didn’t plan how to survive, prosper and procreate, they and their descendant species were naturally selected to do so because their DNA programs suited their environments. Whooping cough bacteria and every other DNA-driven being from 3.7 billion years ago to today are cast members in the great unscripted drama of evolution, not scriptwriters of a fantasy of evolition.

Darwin said that the process he called natural selection is “silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life”.

Striving to survive and make babies that grow to maturity is a very conscious process for humans, so it is unsurprising that we project such volition onto other life forms. Science communicators do best when they resist being infected by that bug.

Simon Grose is a Director of Science Media (sciencemedia.com.au).