Monday, September 15, 2008

Evolution in Your Face

The debate between proponents of evolution and intelligent design (ID) rages on in certain parts of the US. It mostly centers around which one to emphasize, and whether to teach ID at all.

Here's how science is supposed to work: you get the best possible data, and then you create the most logical interpretation of it. I think all interpretations should be presented, including ID and antique scientific theories, but if we want to call it 'science class' then we shouldn't put on kid gloves for anything. The process of teaching science requires cultivating skepticism and independent thinking, and students should be allowed to come to their own conclusions with the facts in front of them.

What many people don't realize is that the facts point overwhelmingly toward evolution. Many American teachers have been tying their hands with the same wimpy anecdotes for decades. Evolution is not just about the fossil record and a few moths somewhere; it's a dynamic process that's happening around us at all times.

I'm constantly dealing with it in the lab. For example, sometimes by chance I'll create a mutant strain of yeast that grows slowly. I'll streak it out on a petri dish. Five days later, one out of twenty of the colonies growing on that plate will have mutated into faster-growing strains. These mutations are called 'suppressors' because they suppress slow growth. If I then take all the yeast on that plate and put them in liquid medium, by the next day, 99% of the cells will be of the faster-growing variety. The slow ones get left in the dust. That's natural selection.

Another example is antibiotic resistant bacteria. All you need is a selective pressure, in this case an antibiotic, and over time if an organism survives it will rise to the occasion. Bacteria are frighteningly rapid at adapting because there is a huge population of them and they have an extremely short generation time. But the same process applies to all organisms, usually on a longer timescale.

Science teachers should use the full repertoire of evidence supporting evolution, including allowing students to participate in natural selection experiments in yeast and bacteria. I think if students could
see evolution, if it became tangible for them, they would realize the debate is a charade. Believe ID if you wish, but don't call it science.

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