Most people think of evolution producing useful traits. But isn’t it also supposed to get rid of useless ones? Science Daily reported work by researchers trying to figure that out.
The National Evolutionary Synthesis Center in Durham, North Carolina sponsored a team seeking to explore the removal of useless traits by natural selection – termed “relaxed selection” in the literature. “Numerous cases of trait loss illustrate that evolution isn’t necessarily progressive, said one co-author of the study published in Trends in Ecology and Evolution. Another co-author added, “It seems that not all the same evolutionary rules are followed when you’re losing a trait as when you’re gaining it.”
The closest thing to a law or principle they found is that traits tend to get lost faster if they cost more. “The biggest reason why a trait goes away quickly is because it’s costly,” that same co-author said. As an example, they cited blind cave creatures whose eyes deteriorate in the dark. Presumably it requires too much metabolic energy to maintain eyesight.
The article was too short to say how they measure cost, or whether exceptions to the rule had been found. Presumably it is easier to lose genetic information than gain it – raising doubts about whether natural selection theory applied to one has anything to do with the other. The cover of the journal shows a cartoon of a herd of zebras standing at a safe distance from a relaxed lion sipping lemonade with an iPod headset on.
Once again, evolutionary theory shows its inherent plasticity. It can explain opposite things (see “Evolution Goes Forward, Backward and Sideways,” 12/19/2007). Every law in evolutionary biology is subjective and riddled with exceptions (see 09/15/2008). Biologists moan over the fact that their evolutionary theories do not have the regularities of physics 08/22/2005). This should raise real questions whether evolutionary biology, which tries to reconstruct an unobservable history, deserves the status it gets in science. Maybe it should be classed under Divination (03/14/2003 and 01/25/2008 commentaries).