Tuesday, April 23, 2013

The Rock Pocket Mouse

The hallmark of a good scientific hypothesis is its ability to make accurate predictions. One of the things that makes the Theory of Evolution so powerful is its ability to make specific, accurate predictions.

The rock pocket mouse is native to the New Mexico desert and has been a research interest of Dr. Michael Nachman of the Howard Hughes Medical Institute.

The pocket mouse is a lover and not a fighter. Dr. Nachman refers to the little thing as the "Snickers Bar" of the desert. It's on just about everyone's menu. Snakes, foxes, owls and even the occasional hawk love to munch on the pocket mouse.

His only hope for seeing another day is to not be seen by the predators that are looking for a quick snack or a light lunch. The mouse's light tan, sand colored fur is its best defense.

Now about 1,000 years ago there was a lava flow in the desert that, when it cooled, turned areas of the ground black. A pocket mouse on a black surface might as well put up a "free lunch" neon sign.

So, if evolution is correct, mice living on the lava flows should have evolved darker fur. That's prediction #1.

Sure enough, pocket mice that live on the lava flows are actually black and not sandy colored.

Prediction #2, there should therefore be an identifiable genetic change that causes the mice to have dark fur and, sure enough, that's precisely what Dr. Nachman and his associates found.

But what about the fact that there are black furred mice on different lava flows hundreds of miles apart? The probability of the same genetic mutation occurring in all of those cases is very, very small. Therefore, prediction #3, there should be different genetic mutations that caused darker fur in different groups of pocket mice and, sure enough, that's exactly what was found.

But wait a minute. The lava flow only occurred about 1,000 years ago. Isn't that too short a time for a genetic change to work its way through an entire population?

Nope, because mice have lots of offspring in a short period of time. Even a slight advantage of 5%-10% allows the change to propagate in a couple of hundred years.

Now granted this is what creationists call "microevolution." There's no speciation involved but so-called "macroevolution" is simply microevolution over a very long period of time. There is no known factor that limits evolutionary change.

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