Top Ten Evolution Articles from New Scientist

 
In my opinion, New Scientist is the best of the current crop of science magazines for the general public, although, in all honesty, the competition is not very challenging.

New Scientist has published Darwin's dangerous idea: Top 10 evolution articles. Most of them are fairly respectable. The main exception is an article on epigenetics [Rewriting Darwin: The new non-genetic inheritance]. That article is an embarrassment.

One of the best articles is Evolution: 24 myths and misconceptions. I've already posted my kudos at: Evolution: 24 myths and misconceptions. One of the nicest things about the series of articles is their description of random genetic drift as an important player in evolution; for example, Evolution myths: Natural selection is the only means of evolution.

Which brings me to the last article in the top ten list: Freedom from selection lets genes get creative. Here's what it says about random genetic drift.

Natural selection, first identified by Charles Darwin in On the Origin of Species, occurs when genetic mutations cause changes in the body and behaviour of an animal that affect its ability to survive and pass on its genes. Some mutations will have positive effects, others may kill an animal outright or somehow affect its offspring's ability to survive and reproduce. Harsh climates, sparse food and relentless predators destroy many individuals, leaving only those that survive best under exactly those pressures. As a result, the more intense the pressure of natural selection, the tighter the fit between a species and its niche.

So, what happens when the pressure is off? You might think there would be little impetus to adapt, so that species would pretty much stay the same. Not so, says Deacon. Animals still change because genes mutate all the time. The constant rewriting of DNA supplies the raw material from which natural selection picks its winners and losers, and when selection is relaxed, the process of weeding out is less ferocious. Instead, a process called genetic drift kicks in as mutations proliferate and animals with a much wider variety of traits are able to survive and reproduce. Some of the classic traits of a species may be lost, while others can arise for no reason other than that it simply doesn't matter if they do.

Close, but it doesn't quite merit a cigar. Drift does not "kick in" when selection pressure is lifted. Drift occurs all the time. It even competes with natural selection.

And while it's partially true that, "the more intense the pressure of natural selection, the tighter the fit between a species and its niche" it's also true that intense "pressure" increases the chance of extinction.

It seems strange that popular journals can publish articles about evolution that disagree with each other and nobody (editors?) seems to notice.

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