March 23, 2005

Evolution: The Controversy


Mary was good enough to forward me a link to an essay explaining that evolution is a fact and a theory at the very same time.

How can this be? It's fairly simple, but apparently you'd be hard pressed to explain that to the people who run the websites in the image to the left of this post.

(GMail, as most of you probably know by now, displays a strip of Google's text ads down the side keyed to notable words in the text. Google's regular searches come up with an admirable array of sensible sites on their ads, but apparently worthy supporters of disseminating the facts missed the GMail loophole.)

Arguments like these suppose that merely because a thing like an eye is complicated, that it simply could not have evolved. But eyes, or light sensitive cells, have evolved separately over 40 times. As the previous link pointed out, even single celled organisms can respond to light. Why is it so hard to believe that an aggregate of specialized cells might not have a few devoted to sensing movement and color?

Evolution is kind of like a market, in the sense that you have a system based on a few basic rules which produces behavior so complex that we still don't have a complete and predictive model of how it works. Evolution works because not every life form is as well adapted as every other. When a cell or animal survives to successfully reproduce, more of them get made.

Here's an example where even this simple thing produces what can be a counterintuitive result. How is it that sexual reproduction evolved when asexual reproduction seems so much more advantageous?

An asexual organism can produce many offspring and does not need to find another member of its species in order to perpetuate itself, which seems pretty handy. But asexual reproduction alters the genome relatively infrequently, so the development of new and complex structures takes quite a while. Sexual reproduction shuffles the deck so frequently that many new combinations are tried. Errors are made, some changes aren't advantageous, and sometimes individuals don't ever meet up with a partner. Yet with all these obstacles, critters that use sexual recombination of genes have flourished because there was plenty of room at the top in niches that asexual organisms never became complicated enough to exploit.

But I yield the floor to someone who really knew what he was talking about. I give you Stephen J. Gould, from Discover, 1981, as quoted from the first essay:

... Well evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty. Facts are the world's data. Theories are structures of ideas that explain and interpret facts. Facts don't go away when scientists debate rival theories to explain them. Einstein's theory of gravitation replaced Newton's in this century, but apples didn't suspend themselves in midair, pending the outcome. And humans evolved from ape-like ancestors whether they did so by Darwin's proposed mechanism or by some other yet to be discovered.

Moreover, "fact" doesn't mean "absolute certainty"; there ain't no such animal in an exciting and complex world. The final proofs of logic and mathematics flow deductively from stated premises and achieve certainty only because they are not about the empirical world. Evolutionists make no claim for perpetual truth, though creationists often do (and then attack us falsely for a style of argument that they themselves favor). In science "fact" can only mean "confirmed to such a degree that it would be perverse to withhold provisional consent." I suppose that apples might start to rise tomorrow, but the possibility does not merit equal time in physics classrooms.

Evolutionists have been very clear about this distinction of fact and theory from the very beginning, if only because we have always acknowledged how far we are from completely understanding the mechanisms (theory) by which evolution (fact) occurred. Darwin continually emphasized the difference between his two great and separate accomplishments: establishing the fact of evolution, and proposing a theory--natural selection--to explain the mechanism of evolution. ...

Researchers have been slowly piecing together how these things work. As they find these answers, they'll have better ideas about how to treat diseases, manage pests, and improve crops. Maybe not directly, but it's all part of finding out how things work, you get nifty side benefits.

The question is whether any of that matters.

It's not entirely surprising that people may sometimes distrust science. We were supposed to have better living through chemistry, but instead we're choking the planet and poisoning our bodies. Military applications of science purport to decrease or more easily mitigate conflict, but instead it grows more deadly. We don't have rocket cars, floating cities, or a cure for aging. It's been over-promised, and in many respects has under-delivered.

Many scientists love their work, and can see its potential somewhere down the road as if it were just within reach. It's easy to underestimate how long it will take to bring that potential to life. Great changes were held out before us, but in many cases, when those changes came they just reinforced a distrust of change in the first place.

Yet knowledge is like any other power. It can be used well or shabbily, by good people and bad. Even radioactivity can be used to treat cancer and power cities.

This seems far off topic, but I think that a big part of cultural backlash, and by extension the backlash against science, is simply disappointment. Progress has been made, but by no means without undesirable side effects.

It isn't just far right conservatives who sometimes wonder if we shouldn't roll it all back. If maybe too many people are doing too many things they don't understand and can't really handle. As long as there have been cities there have probably been periodic surges of interest in going back to the country. David Neiwert has pointed out that the beating core of fascism is a misguided devotion to an ideal of lost purity.

So here, at long last, is a point. I don't think that so many are rejecting evolution because of evolution itself. There are plenty of good supporting arguments in its favor, and maybe they need to be put out in public a little more, but I doubt that will do it. If the fundamental dissatisfactions and fears that lead people to reject modernity aren't addressed, we can argue ourselves blue in the face with the best explanations and it won't matter.

There are two ways out of this dilemma: to go back, or to go through. If civilization is unable to correct the problems that lead to widespread mistrust of even its benefits, it can easily become an instrument for expressing the deep seated fears and prophetic longings of those who see anything smacking of progress as a cataclysm in the making.

As much as I'd like people to be more aware of the basic facts of biological existence, I wish more that we knew half as much about effectively managing our own affairs as we do about our genetic history.

Posted by natasha at March 23, 2005 12:11 AM | Science | Technorati links |

I like the point that evolution is both a theory and a fact, and I also agree that it's pretty hard to explain.

In a sense everything we know is a theory. For example, I could be dreaming all this. Instead, I choose the "theory" that the world has an independent existence.

Paul Krugman likes to say that if the Bush Administration announced that the world is flat, the newspapers the next day would headline: "Shape of Earth: Views Differ."

Yes, the round-Earth "view" is a theory. It happens to be the best theory of the Earth's shape we have. A few centuries ago perhaps that theory would have been ridiculed --- just as the best theory of the complexity of life on earth is now ridiculed by some.

That doesn't make it any less a fact.

Posted by: Ralph at March 23, 2005 08:05 AM