3/07/2009

SIMULATING SELECTION

You know, if people can actually play with the mathematics of evolution they can learn a few things.

For example, evolution doesn't always lead to 'progress' in the sense that some mutation occurs, leading to increased fitness. Sometimes the mutation is lost, sometimes it oscillates in frequency within the population, sometimes a 'backward' mutation changes the frequency which had previously been fixed at 100 percent within the population. One very real possible result of evolution, according to the math, is stasis.

Amazingly, in my recent debates with Terry Scambray, he seemed to regard Gould and Etheridge's* famous attempt to describe one possible pattern often seen in the fossil record not just as an oxymoron (he is a retired English prof), but also a form of question-begging at odds with what evolution should predict. But in fact, G and E's 'punctuated equilibrium' is precisely what we are likely to see in many scenarios.

Not convinced? Go to this post on 'The Panda's Thumb' and play with the Java applet. You'll note pretty quickly that a number of different scenarios can play themselves out when you run the simulation multiple times. In other words, if you do the math, you'll find that none of the different patterns of populations change observed in nature (including those seen in the fossil record) seem outlandishly different from those allowed by evolutionary theory.

* OOPS! I mean Eldridge! Must've been channeling my inner Melissa.

2 comments:

Ed Darrell said...

Etheridge? Not Eldredge?

Scott Hatfield . . . . said...

Must have been channeling my Inner Melissa. Sorry!