Evolution myths: Mutations can only destroy information
Biologists are uncovering thousands of examples of how mutations lead to new traits and even new species. This claim not only flies in the face of the evidence, it is also a logical impossibility
Most people lose the ability to digest milk by their teens. A few thousand years ago, however, after the domestication of cattle, several groups of people in Europe and Africa independently acquired mutations that allow them to continue digesting milk into adulthood. Genetic studies show there has been very strong selection for these mutations, so they were clearly very beneficial.
Most biologists would see this as a gain in information: a change in environment (the availability of cow's milk as food) is reflected by a genetic mutation that lets people exploit that change (gaining the ability to digest milk as an adult). Creationists, however, dismiss this as a malfunction, as the loss of the ability to switch off the production of the milk-digesting enzyme after childhood.
Rather than get bogged down trying to define what information is, let's just look at a few other discoveries made by biologists in recent years. For instance, it has been shown a simple change in gene activity in sea squirts can turn their one-chambered heart into a working two-chambered one. Surely this counts as increasing information?
TRIMming the genome
Some monkeys have a mutation in a protein called TRIM5 that results in a piece of another, defunct protein being tacked onto TRIM5. The result is a hybrid protein called TRIM5-CypA, which can protect cells from infection with retroviruses such as HIV. Here, a single mutation has resulted in a new protein with a new and potentially vital function. New protein, new function, new information.
Although such an event might seem highly unlikely, it turns out that the TRIM5-CypA protein has evolved independently in two separate groups of monkeys. In general, though, the evolution of a new gene usually involves far more than one mutation. The most common way for a new gene to evolve is for an existing gene to be duplicated. Once there are two or more copies, each can evolve in separate directions.
The duplication of genes or even entire genomes is turning out to be ubiquitous. Without a duplication of the entire genome in the ancestor of modern-day brewer's yeast, for instance, there would be no wine or beer. It is becoming clear that every one of us has extra copies of some genes, a phenomenon called copy number variation.
The evolution of more complex body plans appears to have been at least partly a result of repeated duplications of the Hox genes that play a fundamental role in embryonic development. Biologists are slowly working out how successive mutations turned a pair of protoHox genes in the simple ancestors of jellyfish and anemones into the 39 Hox genes of more complex mammals.
Newly minted
Can mutation really lead to the evolution of new species?
Yes. Several species of abalone shellfish have evolved due to mutations in the protein "key" on the surface of sperm that binds to a "lock" on the surface of eggs. This might appear impossible, but it turns out that some eggs are prepared to be penetrated by deviant sperm. The same thing can happen in fruit flies, and likely in many other groups too. In yeasts, the mutations that led to some new species forming have not only been identified, they have even been reversed.
The list of examples could go on and on, but consider this. Most mutations can be reversed by subsequent mutations - a DNA base can be turned from an A to a G and then back to an A again, for instance. In fact, reverse mutation or "reversion" is common. For any mutation that results in a loss of information, logically, the reverse mutation must result in its gain. So the claim that mutations destroy information but cannot create it not only defies the evidence, it also defies logic.
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