Why Does Natural Selection Take So Long

In an item on The Register about why natural selection takes so long to get results, Dr Stephen Juan, an anthropologist at the University of Sydney makes several statements that seem to me to be at odds with evolutionary theory.

“Most mutations do not help the species survive.”

This is true in one sense, but natural selection doesn’t act on species, all it does is remove individuals from the gene pool that are no longer best adapted for a particular environment. If a mutation in an individual’s DNA mean it is better adapted to a changing environment then it will pass the “new” gene(s) on to its offspring who will then have the trait and the viability in that environment to reproduce and so on.

“A species and an environment exist in balance with each other.”

Do they? Perhaps, but only in the sense that should either one change radically then we will no longer observe a balance. Moreover, several mutations over several generations that allow individuals to cope with a changing environment leads to species diversity.

“Populations simply adapt to their current surroundings and to changes in those surroundings.”

No they don’t. Individuals either survive the new surroundings and pass on their genes to their offspring or they don’t. Usually, only those best adapted to new environmental conditions survive to do so. Populations may display synergetic effects between individuals but this is not the same as a population adapting.

“They do not necessarily become better in any absolute sense over time.”

There is no such thing as “better” or “worse” evolutionarily speaking. An individual either survives and passes on its genes or it does not. If those genes endow the offspring with the ability to survive and pass the genes on again then the genes survive. If they don’t they are lost. Evolution is littered with dead-ends but every single living thing on the planet has ancestors that were capable of reproducing.

facebooktwittergoogle_plusredditpinterestmail