Friday, March 19, 2010

Nonsense at the Guardian

It is always a bit amusing when a non-scientist uses a tired analogy to prove a point that he or she wants to make. Oliver Burkeman of the Guardian is just such a non-scientist. He has written a piece called Why everything you've been told about evolution is wrong. That is an exceedingly tall order so let's see why he thinks this. He writes:
Inevitably, those of us who aren't professional scientists have to take a lot of science on trust. And one of the things that makes it so easy to trust the standard view of evolution, in particular, is amply illustrated by the legend of the Nasa astronomers: the doubters are so deluded or dishonest that one needn't waste time with them. Unfortunately, that also makes it embarrassingly awkward to ask a question that seems, in the light of recent studies and several popular books, to be growing ever more pertinent. What if Darwin's theory of evolution – or, at least, Darwin's theory of evolution as most of us learned it at school and believe we understand it – is, in crucial respects, not entirely accurate?
This reminds me of the simulated conversations between the student and the teacher in which the student asks a question that the teacher cannot answer and gets flustered about. What if it is wrong? Burkeman focuses on epigenetics, the idea that changes that occur to an individual during life can have an influence on their descendents in terms of their abilities to do certain things. He gives several examples, all mysteriously from Sweden, in which he mentions how this plays out in chicken populations and in children whose abilities seem to be holdovers from their parents. Here is the chicken example:
Take, to begin with, the Swedish chickens. Three years ago, researchers led by a professor at the university of Linköping in Sweden created a henhouse that was specially designed to make its chicken occupants feel stressed. The lighting was manipulated to make the rhythms of night and day unpredictable, so the chickens lost track of when to eat or roost. Unsurprisingly, perhaps, they showed a significant decrease in their ability to learn how to find food hidden in a maze.

The surprising part is what happened next: the chickens were moved back to a non-stressful environment, where they conceived and hatched chicks who were raised without stress – and yet these chicks, too, demonstrated unexpectedly poor skills at finding food in a maze.
This simply isn't news. And it sure as heck isn't epigenetic. If a healthy woman undergoes a significant amount of stress, be it environmental or psychological, it affects her ability to conceive and bear a healthy child. Countless studies have shown this. What Burkeman doesn't say, and what is elucidated by Jerry Coyne, is that within two generations, the chickens had returned to normal, as had the children. The examples, therefore, demonstrate nothing whatsoever in terms of epigenetics.

It gets worse, however. He interviews one of the authors of the book What Darwin Got Wrong, Jerry Fodor about the inability of natural selection to power evolutionary change. Berkman writes:
I called Fodor and asked him to explain his point in language an infant school pupil could understand. "Can't be done," he shot back. "These issues really are complicated. If we're right that Darwin and Darwinists have missed the point we've been making for 150 years, that's not because it's a simple point and Darwin was stupid. It's a really complicated issue."

Fodor's objection is a distant cousin of one that rears its head every few years: doesn't "survival of the fittest" just mean "survival of those that survive", since the only criterion of fitness is that a creature does, indeed, survive and reproduce? The American rightwing noisemaker Ann Coulter makes the point in her 2006 pro-creationist tirade Godless: The Church of American Liberalism. "Through the process of natural selection, the 'fittest' survive, [but] who are the 'fittest'? The ones who survive!" she sneers. "Why, look – it happens every time! The 'survival of the fittest' would be a joke if it weren't part of the belief system of a fanatical cult infesting the Scientific Community."
This is facile. Every generation, there are changes that occur in any given environment and for every given generation, there are a host of mutations that express themselves in the population. Selection acts on the traits that are present in the individuals of a population in such a way that some traits are more selectively advantageous and some are not. Those that possess the advantageous traits tend to leave more offspring. This perpetuates (usually, not always) the existence of these traits in the population. This is not a hard concept.

Here is an example: in west Africa, malaria is prevalent. Recent advances have beaten back the disease but it still exists. Malarium falciparum, requires nice healthy red blood cells to do its job and it makes people with the parasite very ill. Conversely, many individuals in the area suffer from a deadly mutation that causes the red blood cells to form a "sickle" shape and, thus, not deliver enough oxygen to the cells. If you have two alleles for this trait, the trait expresses itself. If, however, you only have one allele that produces the sickle cell, you express the illness in a reduced form and it is manageable. The parasite doesn't like you, however, so you don't get malaria. Consequently, these two forms of the red blood cell gene are maintained in populations in West Africa.

During the slave trade, however, many African blacks were brought to the New World, where there is no malaria. As Darwin's theory of selection would predict, the frequency of the sickle cell allele is dropping like a rock. In the absence of selective pressure to maintain it in the population, it is being selected against. That is how selection works and that is how populations respond to selective pressures. There are countless examples of this in the natural world and even some examples of artificial selection to breed hardiness into a species of plants or animals. I have not read Fodor's and Piattelli-Palmarini’s book (too many other things to read) but if that is the gist of it, there is little point. Guardian readers would be best served by skipping this piece by Burkeman.

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