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Some thoughts on evolution

No, this is not an Evolution Versus Creationism Death Match. Really, there's only so many times one can watch Godzilla squash Bambi before it ceases to be amusing any more.

Rather, this is a post intended to clear up some popular misconceptions about how evolution works. I've been meaning to write it for a long time, and some comments made at a Dragon*Con panel reminded me that I still haven't ranted about this in my journal. So, it's high time to get my rant on!

There are two popular notions about evolutionary processes that I hear all the time, often from folks who ought to know better, and they tend to get under my skin. The first is that evolution is no longer operating on human beings; the second is that evolution is goal-directed, that it makes a species "better." Ready? Here we go!

Evolution still operates on people, just as it always has

"Evolution is about survival of the fittest," people say. "Today, thanks to the miracles of modern technology, people who would have died a hundred or a thousand or ten thousand years ago can be kept alive. They don't die off, so their genes still spread. So that means we've stopped evolving."

Fine, except that it's wrong. Evolution isn't about survival of the fittest. That wasn't Charles Darwin's phrase; it was coined by Herbert Spencer, and was included in On the Origin of Species only at the fifth reprint, as it had become popular by that time.

But evolution is not, and never has been, abut "survival of the fittest." That's an overly simplistic and inaccurate view of how evolutionary processes work. Evolution is about the propagation of those genes which most enable an organism to...propagate its genes. What's good for the gene is often, but not necessarily, what's good for the organism; a gene that shortened its host's life by fifteen years but increased the probability that its host would reproduce by .01% would do quite well in the evolutionary game.

(As a segue, I've frequently heard an argument against transhumanism in general and life extension in particular that says "Mortality and a finite life expectancy must be good for us. If they were not good for us, then we would not have evolved to have a finite life span. So the fact that we have evolved in such a way means that there is some benefit to being mortal." This argument does not hold water, because the bulk of our evolutionary heritage comes from a time when most members of the species would die through accident, disease, or predation far, far before they would die of old age. A gene that conferred immortality offers no reproductive benefit to a species whose members are killed by leopards, diseases, tumbles off a cliff, or each other before they're thirty. Ergo, such a gene would not be selected in favor of. We have genes that confer mortality because there's no advantage to genetic immortality.)

Evolution is not about survival of the fittest. It's about the genes that spread. Evolution needs only three things to operate, namely:

1. A population whose individuals are different from one another;
2. A system whereby those differences are heritable; and
3. A system whereby those differences make a difference in how likely an individual is to reproduce.

That's it. That' all it needs. And yes, you have those things in humanity. We are not all the same; the differences between us can be transmitted to our children, and sometimes, those differences make a difference in how likely we are to have children, or how many children we have.

Contrary to the crude understanding of evolutionary processes so common in pop culture, it is not necessary for individuals who have a particular trait to die for that trait to be selected against. If a particular gene--a gene making its bearer more likely to have asthma, say--decreases the odds that a person will reproduce by 0.01%, that's enough. If even one person out of ten thousand has one fewer child because of a particular gene, then evolution is still working.

Modern medicine keeps many people alive today who would die in a pre-industrial society. That does not mean that people with detrimental genes have exactly the same number of children at exactly the same rate as people without that gene. As long as a particular gene has any impact on the number of children its hosts have, however slight, evolution still works.

Evolution is not goal-directed

Evolution does not make a species "better" for any value of "better" that people often use. Evolution favors genes that make its hosts more likely to reproduce. That's it. A gene that causes you to die of a horrifying, debilitating cancer after you hit menopause isn't going to be selected against.

Furthermore, evolution is completely blind with regards to "better" and "worse" as human values. At the panel, one person used Down's syndrome as an example of how evolution no longer applies to human beings. If people with Down's, he reasoned, have children, then how can evolution make the human species better?

This question falls down on a number of levels, and shows a lack of understanding of what evolution is. Down's syndrome is not generally heritable; it's caused by a particular genetic malfunction that does not, usually, affect the gametes.

But leaving that aside for the moment, let's assume that it is heritable. What does that mean? If people with Down's syndrome had more children than people without it, then from an evolutionary perspective, Down's syndrome would be "better." From an evolutionary standpoint, there is one and only one definition of the word "better," and that is "more likely to reproduce."

I mean, if you think about it, I am a worst-case scenario. I have not had children at all, and I have even opted for voluntary sterilization, so I never will have any children. My particular collection of genes is a dead end. I am, evolutionarily speaking, the poorest possible outcome. From the perspective of the processes we're talking about, a person who has Down's syndrome and has children is better than I am.

It frustrates me that American culture is so divided and American politics is so wrapped up in the idea of evolution, yet very few people even understand what "evolution" is. They feel passionately about it, but they're incapable of articulating the most basic principles of evolutionary biology.

Rant off.



Sep. 5th, 2007 05:39 am (UTC)
I'm not arguing for or against rape as being an evolved behavior. However, I remember when the book A Natural History of Rape came out, the majority of responses to it read something like, "I haven't actually read this book, but it's offensive and wrong!!1!11!!" If you want to accuse researchers of lazy science, then you need to actually read their studies (the actual journal articles) and analyze their methods using scientific standards. And if you do that and you still decide that the science is shoddy, that's fine, that's exactly how science is meant to work. I have no problem with that. It's the folks who immediately dismiss any research that contradicts their world-view that I have a problem with. That and the folks who read a story about a study in USA Today and think they have any ability to judge its worth based on a 300-word mangling of the science.
Sep. 5th, 2007 05:57 am (UTC)
If you want to accuse researchers of lazy science, then you need to actually read their studies (the actual journal articles) and analyze their methods using scientific standards. And if you do that and you still decide that the science is shoddy,

I have, and I did.

It's the folks who immediately dismiss any research that contradicts their world-view that I have a problem with.

Me too. And the world view of women=passive and men=aggressive/men want lots of partners and women want monogamy/men rape because of evolution! tends very much to come from people who have a very sexist worldview. It influences the science--or lack thereof--and their research and their arguments are poorly constructed.

If you've read peer-reviewed articles that express the whole evolutionary-rape thing well, that's great. I haven't, and I've looked. In addition to that there are a bunch of pseudo-intellectual rape-apologists running around quoting (what I believe is) already shoddy research for political reasons. If there are feminists freaking out on one side, there are just as many, if not more, individuals reading USA Today articles and telling me that--evolutionarily speaking--women prefer pink! It's bad science, bad journalism, and a bunch of sexist jerks saying "It must be true!" without putting much thought into it, because they see the world that way anyway.

Personally, I think complex and interesting discussion can be had on the subject--as well as the subject of evolution vs. environment in general--but it's been abused to much for social or political gain that it's not even a scientific argument anymore. Often, it has more to do with social policy.

Point being, I honestly think we're agreeing. We're both bothered by the same thing (lazy/shoddy science) we're just sitting on opposite sides of the issue (presumably), and I'm merely trying to point out that the evolutionary biology camp has its own group of political opportunists.
Sep. 5th, 2007 05:59 am (UTC)
*So much, not "to" much.
Sep. 5th, 2007 06:13 am (UTC)
I think we're agreeing, too. As for whether we're sitting on opposite sides of the issue--I never gave an opinion on the issue. ;-) I merely gave an opinion on people who automatically assume that when someone says a behavior is evolved, that they must be saying it's morally acceptable. Replace "rape" with any other human behavior and it's still an incorrect assumption.
Sep. 5th, 2007 06:25 am (UTC)
I think (and
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I think (and <lj-user="boigrrrlwonder"> can correct me if I'm wrong) that the original point was not so much that "evolved" is inherently a moral distinction so much as it is <i>taken</i> as a moral distinction.

Science does not occur in a vaccuum (har). Researchers are just as likely to have political motivations, or social biases, as just about anybody else. The people funding them are often even <i>more</i> likely to have an agenda.

<i>I merely gave an opinion on people who automatically assume that when someone says a behavior is evolved, that they must be saying it's morally acceptable. Replace "rape" with any other human behavior and it's still an incorrect assumption.</i>

I think it's problematic but fair to make that assumption. It's fair because, especially in the west, I think the vast majority of people out there <i>are</i> making a moral judgment. It's problematic because it perpetuates the assumption. The western world, I think, has trouble doing or thinking anything without ascribing some kind of judgment to it--usually moral.
Sep. 8th, 2007 11:40 pm (UTC)
The whole pink/blue thing is actually involved in advertising changes in the US in the early 1900's.
Prior to that, pink was associated with boys (as it was a milder version of red which was considered a masculine color due to its link to fire) and blue for girls because it was tranquil and calm like the ocean.
So that particular one's memetics, not genetics, but is still linked to biased views of sex & gender :-)
Sep. 9th, 2007 02:52 am (UTC)
The reference was to an article floating around that claims that girls genetically prefer pink, and boys blue, and that it must be because women were gatherers and were looking for ripe fruit, so their eyes would be drawn to red, so they like pink. It's stupid and wrong on about 98709870868976 levels. The study itself showed that all people tend to be drawn to blues and purples, but that women more often tended to be drawn to purple. And that's more red than blue, so that means women like pink!
Sep. 9th, 2007 02:54 am (UTC)
Yup, I'm aware :)
I was just pointing out the idiocy of that given that anyone who's taken a marketing class knows it's a societal construst & only about 100 years old.
Sep. 9th, 2007 03:06 am (UTC)
Ahhh, ok. Sorry if that seemed snippy or defensive. :)
Sep. 9th, 2007 03:07 am (UTC)
's cool ;-)