Friday, July 18, 2008

Well duh.

Natural selection may not produce the best organisms

(Note that so far I've only read the "press-release" news item at this link so far, not the original paper yet.)

"While natural selection favors the most fit organisms around, evolutionary biologists have long wondered whether this leads to the best possible organisms in the long run.

A team of researchers at The University of Texas at Austin, led by Drs. Matthew Cowperthwaite and Lauren Ancel Meyers, has developed a new theory, which suggests that life may not always be optimal."

So... a sequence of local optimizations doesn't necessarily lead to a global optimum?

To anyone who's ever done any optimization, this is completely obvious (it happens all the time!). That's not to say that it's not useful to confirm a pretty well-known fact about optimization in this particular situation - but the way the story is worded, it kind of sounds like they expected different.

I guess this is another of those "try to make every bit of science news sound like a revolutionary breakthrough", as though just plain interesting science is somehow insufficient. If I can get time to read the paper, I will return and write some more.


Anonymous said...

You know some creationists will see this and say, "See? Evolution can't produce best organisms, but all these animals are perfectly adapted to their environment!"

That's ridiculous, of course, since the point is that they AREN'T perfect, but that won't stop the creationists.

Blake Stacey said...

I'll have to read the paper more closely when I'm less scatterbrained (WARNING: INSUFFICIENT CAFFEINE FOR MEANINGFUL RESPONSE), but I can say already that the contrast between the press release and the paper is truly, ahem, vivid. The paper itself goes all the way back to Fisher and Wright's arguments in the olden days, anchors itself in neutral-drift theory, etc. Oh, and its results are based only on short RNA molecules. In other words, it's your typical journal article, exploring a well-known question through the study of a particular example.

Fitness landscapes are a product of ecology, and as such, they naturally change over time. Whether a genotype is positioned at a "global optimum", or even a local extremum, is not a hard-and-fast dictum, but rather a result contingent on the circumstances.

tim said...

"So... a sequence of local optimizations doesn't necessarily lead to a global optimum?"
And just so it's on the record, let's remind visiting creationistas that 'local' includes 'local in time' as well. Since environments change (Oh Noes! We'll have global warming denialidiots turn up now!) over time it should be easy to see how selection pressure can lead to a population change that then turns out to be contra-survival later. It's all about expediency; if you don't survive now it doesn't matter about later.

Efrique said...

Thanks guys. Useful points.

Blake - thanks. I'm not at all surprised there's difference between what the news item implies and what the paper is doing.

tim and blake - I definitely had the sense of "local in time" when writing it, but I didn't discuss it at all; it's worth pointing it out because people may misunderstand that this is a dynamic, not a static, situation, because what is "fit" now is not necessarily "fit" later.

Anonymous said...

I read the press release, too, and then went to read the paper. I couldn't find the relevance from the press release to the work on the article... So, I asked Greg Laden about it.. He told me to delete any reference to the press release cause it was crap.

I had a post all lined up, too, and Greg had to lead me in a different direction. Damned teachers for ya.