Tag: evolution

No, we don’t assume that evolution must increase complexity

Ryan Gregory at Genomicron mocks an inane press release about a supposedly new evolutionary theory – the idea that endosymbionts will lose genes when their hosts or other microbes in their community can provide the functions of those genes. This is an old and widely established idea, so why anyone with any knowledge of recent evolutionary biology would play up this idea as novel is beyond me.

Sadly, the ignorance isn’t limited to whatever flack wrote the press release – at least one of the scientists involved is portrayed as the same misunderstanding of evolution that many creationists have:

“A common assumption about evolution is that it is directed toward increasing complexity,” said Erik Zinser, associate professor of microbiology. “But we know from analysis of microbial genomes that some lineages trend toward decreasing complexity, exhibiting a net loss of genes relative to their ancestor.”

Okay kids, repeat after me: evolution is not based on an assumption of increasing complexity. Increasing complexity (leaving aside the fact that the word complexity is terribly vague and non-quantitative) often happens in evolution, but we don’t assume that this is what should happen.

UPDATE: It could be that I’m being unfair to Dr. Zinser, that he’s being selectively quoted in a bad way by the same person who wrote the rest of the misguided press release. If that’s true, then all of my disdain is reserved for the anonymous press release writer.

Just-So Stories

On this week’s episode of Skeptically Speaking, host Desiree Schell interviewed Mark Changizi about his book, The Vision Revolution. I listened to the live taping this past Sunday at what I believe George RR Martin would have referred to as the “hour of the eel” here in England.

Changizi is never short of interesting ideas, and a researcher should always make the strongest case for their ideas that they can. Unfortunately, I have some issues with the evidence supporting that “strongest case” and the way he presents it: Continue reading “Just-So Stories”

Prejudice is rational if you assume prejudice is rational

Yesterday, PLoS One published a study entitled “The Rationality of Prejudices” by Thomas Chadefaux and Dirk Helbing, which argues that being prejudiced can be an efficient strategy:

We model an -player repeated prisoner’s dilemma in which players are given traits (e.g., height, age, wealth) which, we assume, affect their behavior. The relationship between traits and behavior is unknown to other players. We then analyze the performance of “prejudiced” strategies. . .Such prejudiced strategies have the advantage of learning rapidly. . .they perform remarkably well. . .when the population changes rapidly.

The key assumption is right there in the abstract:

We model an -player repeated prisoner’s dilemma in which players are given traits (e.g., height, age, wealth) which, we assume, affect their behavior. (emphasis added)

In short, the researchers are starting with the assumption that the prejudices are true. Continue reading “Prejudice is rational if you assume prejudice is rational”

Spider Silk

So, hi, if you happen to be my mom, you might want to stop reading now. As the title indicates, this is a review of a book that is all about spiders. SPIDERS!!!

My mother does not like spiders. She really, really does not like spiders.

But I do[1].

I approached Leslie Brunetta and Catherine L. Craig’s Spider Silk with hope and dread. Hope that I might learn a lot more about spiders. Dread that the authors would mangle evolutionary theory with over-simplification while trying to use spider silk to teach the general public about natural selection.

One of these emotions was unnecessary and wrong. Continue reading “Spider Silk”

Gene Networks and Natural Selection

This was originally posted at Adaptive Complexity, but it might be of interest to our patrons here at The Finch and Pea.

Life can be brutal for yeast in the wild. You don’t know where your next meal is coming from or what form it’s going to take. The key to being a successful yeast is to be metabolically agile, able to switch your metabolic state quickly based on the food source that’s currently available on the bark of an oak tree or in the leaf litter of a forest floor.

So yeast, especially the set of species related to baker’s yeast, have various networks of genes that specialize in making a meal out of different sugars. A yeast has to detect, pump in, and break down various sugars like sucrose, galactose, maltose, and glucose. Each of these sugars has different chemical properties, and therefore yeast requires different sensors, transporters, and enzymes to use each as a food source. Continue reading “Gene Networks and Natural Selection”