Blue Collar Scientist

Over at The Loom, science writer extraordinaire Carl Zimmer writes about some recent experiments on E. coli:

Scientists randomly rewired the network of genes that control much of the microbe’s activity and found that it generally just kept humming along.

Wow. And here I always thought that the genome was sensitive to changes, and that wholesale re-arrangement would seriously mess things up for an organism.

Turns out that was a little corner of my thinking that had been contaminated by silly creationist claims:

This conclusion also flies in the face of the popular misconception among opponents of the evolutionary theory, who believe that the genetic code is irreducibly complex…. Engineered devices are generally designed to work just above the point of failure, so that any tampering with their construction will result in catastrophe…. But nature does not have that option. To survive … organisms must be able to tolerate random mutations, deletions and recombination events.

In other words, here we have yet another prediction of intelligent design creationism which has been blown apart by scientific experiment.

I encourage reading the whole thing - very instructive.

For years, creationists have shrilly insisted that the more complex a life form is, the slower it could evolve adaptive traits. Supposedly this showed that evolution wouldn’t work, or something.

Of course, just bleating that something is true doesn’t make it so. And as in so many other cases when we are dealing with creationist rhetoric, this one isn’t true either.

Yesterday Nature published a paper with the inspiring title Pleiotropic scaling of gene effects and the ‘cost of complexity.’ The experiments described in the paper deliver a body-blow to the so-called “cost of complexity” hypothesis.

The researchers did something very straightforward - they caused mutations in mice, and then measured the results. If the “cost of complexity” crowd were right, then making a single genetic mutation should affect many different unrelated traits. If they were wrong, then the effects would be limited to either a single trait, or several related traits. The researchers found that the latter was the case.

A more technical way of discussing the findings is to say that pleiotropies are rare. A pleiotropy exists when a single gene strongly affects a variety of phenotypic traits. While pleiotropies do exist - a famous example causes phenylketonuria in humans - the study shows that they are not common in a broad sample of gene mutations, as creationists claimed. As a consequence, even complex organisms can adapt through mutation without paying a price for their complexity.

From the abstract:

As perceived by Darwin, evolutionary adaptation by the processes of mutation and selection is difficult to understand for complex features that are the product of numerous traits acting in concert, for example the eye or the apparatus of flight. Typically, mutations simultaneously affect multiple phenotypic characters. This phenomenon is known as pleiotropy…. Some authors have suggested that pleiotropy can impede evolutionary progress (a so-called ‘cost of complexity’)…. Here we show, by studying pleiotropy in mice with the use of quantitative trait loci (QTLs) affecting skeletal characters, that most QTLs affect a relatively small subset of traits and that a substitution at a QTL has an effect on each trait that increases with the total number of traits affected. This suggests that evolution of higher organisms does not suffer a ‘cost of complexity’ because most mutations affect few traits and the size of the effects does not decrease with pleiotropy.

Wired has a nice article about the paper including some quotes from the PI:

“I think the main broader impact of this work is on the evolution-creationism debate,” wrote [Yale University evolutionary biologist Gunter] Wagner in an email. “I would say the only intellectually interesting argument that the creationists are using, at least the scientifically more sophisticated ones, is that random mutation can not lead to the evolution of complex organisms. And there are interesting mathematical arguments that have been made to support that. But our results show that organisms found a way around that problem by restricting mutational effects on very narrowly confined parts of the organisms.”

This paper undermines the whole creationist argument based on information theory that has become so popular in recent years. This should be remembered, and pointed out when creationists trot out their silly claims.

I guess it is stale story day. Having just discussed a three week old astronomy story, now we’re going to look at a week-old news story that apparently just hit the US. By way of the Tracker, I’ve learned that every single blue-eyed person on the planet shares a common ancestor who lived just 6,000 to 10,000 years ago.

The press release has some of the details, but it boils down to this. Blue eyes may have appeared in humans a number of times, but the first time that someone with blue eyes stuck around and had enough children to perpetuate the gene across the globe was 6 kya to 10 kya. The blue eyes were the result of a mutation in a gene called OCA2. As the principal investigator puts it, all blue-eyed people

“have all inherited the same switch at exactly the same spot in their DNA.”

What is the meaning of the mutation?

The mutation of brown eyes to blue represents neither a positive nor a negative mutation. It is one of several mutations such as hair colour, baldness, freckles and beauty spots, which neither increases nor reduces a human’s chance of survival. As Professor Eiberg says, “it simply shows that nature is constantly shuffling the human genome, creating a genetic cocktail of human chromosomes and trying out different changes as it does so.”

This is evolution in action. Evolution isn’t trying to make a better creature, it is just making the next generation different from the previous one. In the original blue-eyed person’s case, they were different in that they had a unique eye color. But their descendants inherited their version of the gene and this variation spread through a fairly significant proportion of the population.

As the PI notes, the change was neither bad nor good, on average. Anecdotally, I’ve observed that my blue-eyed friends tend to have a tougher time with eye fatigue on glaciers, snowshoeing, or cross country skiing, than I do (the BCS is brown eyed). This may or may not be significant, but if it is significant, there is certainly plenty of evidence that blue eyes are subject to sexual selection in the culture in which I live - so that would be a benefit to the blue-eyed crowd. If there’s any downside, it’s offset by an upside, but the PI is probably right - this mutation is neither good nor bad.

There’s a more fundamental issue here, though. The change in gene OCA2 is referred to pretty universally as a mutation. That means blue-eyed people are mutants.

Expect the playground taunts to commence forthwith. :-)

Of course this is true - blue-eyed people are mutants. But so is everyone else. We are all a collection of mutations, some of them good, some of them bad, some of them neutral when it comes to engaging with the world around us. Every gene that we don’t share in common with chimpanzees, and every gene they don’t share in common with us, is proof of the bundle of mutations we’re made with. And you can take that right down the line to each of our ancestors back to the beginning of life - the degree to which we differ from a starfish is the degree to which both we, and starfish, are mutants.

I know some creationists who would strenuously object to being called a mutant. They believe they were made by god, and that god made them perfectly, and that god on purpose introduced any perceived flaws in their construction. Calling someone a mutant radically undermines this perception, and if you bandy this idea about, you’ll get push back from them. Mutants are, in their perception, abominations - things that represent an active fight against god and his supposed desires.

It is yet another illustration that the language we¹ use is completely different from that of creationists. I suppose it goes beyond language, and in fact indicates a completely different reality that we live in. But our reality is, I think, better. A world in which “mutant” is understood to refer to someone who has some sort of small chemical difference in some molecules in their body works for me. A world in which a mutant refers to someone debased, whose very existence flaunts an inner hostility to some supposed king of the universe - that world sucks. And that world is with us today - some of our religions require that we kill those who oppose god - and as I’m sure many of us have noticed, plenty of the religious are willing to do just that. Just my opinion, here, but a world in which I have the freedom to look at a blond, leggy, blue-eyed mutant and see a person of beauty is a much better world than one in which “deformed” babies are abandoned by their parents in the outdoors to die of exposure. To put it into modern terms, if a red-eyed baby were born today, I’d much rather the collective reaction of society be along the lines of “cool!” and “radical!” instead of killing the baby as demon-spawn.

And to be a blue-eyed person, and to know that your blue eyes came to you from an ancestor who lived possibly as recently as 6,000 years ago - what a great sense of connection to humanity, and our collective historical experience, that must give someone.

Blue eyed people are mutants. And looking at this from a scientific perspective allows us to see this as something beautiful, something interesting, something worthy of passion, and something that makes our lives rich and worth living.

It must really suck to be a creationist.

1. i.e., science types [↩]