God Hates Shrimp – Part 1

This article in Science Daily got me to thinking about evolution and science.

A while back, when I was talking to a colleague about science, she asked what proof scientists would need to disprove evolution. I glibly said “but we know it works”. Which is a cop-out. Let me make another attempt.

First, let me repeat what I’ve said elsewhere about the language of science. To a civilian, the word “theory” means “a hunch”, but to a scientist it means “a model for explaining observed phenomena”. You can’t prove a theory. All you can do is disprove it.

A theory can be disproved in two ways. First, it can fail a prediction test. If your model of gravity says that it is a universal force, then that would predict that this cannonball and this musketball will land at the base of the Leaning Tower of Pisa at the same time. If they don’t, your model is wrong. Or incomplete.

Second, a theory will fail if it can be shown to be internally inconsistent. My model says that the cannonball will hit first, because it is heavier. But if I duct tape them together, do they fall faster? Or does the lighter musketball retard the speed of the cannonball? I can discard the theory without an experiment.

Notice that neither of these fail mechanisms requires an alternate model, and if there was an alternate model you wouldn’t necessarily have to refer to it. If I remember my history of science correctly, Einstein said that his Theory of Relativity couldn’t be judged in the light of the predictions of other models. It had to succeed or fail on its own terms.

A third way to attack a theory is to develop an alternative that is a better model, that predicts what the old theory does, and makes other predictions as well. The old theory is then usually not so much wrong as incomplete. Newton’s theory didn’t ‘fail’ in the environment in which it was developed. In fact Newtonian gravitation was all that we needed to put men on the Moon. It wasn’t until we went off into the wider solar system that we needed to use Einstein’s theories, because the Newtonian model didn’t predict things accurately enough. The phenomena we were worried about were too small for Newton. Which brings us to shrimp. And evolution. And Darwin.

Darwin’s theory is simple. Inheritable biological changes occur in animals — no two puppies in a litter are identical. The external environment for those animals (let’s call it Nature, without getting too anthropomorphic) is such that some of these changes improve the probability that an animal with that change will have more surviving offspring. Since the biological change is inheritable, you tend to get more and more animals with the changed biology until you get a different species. Darwin’s finches were able to exploit different ecological niches and so developed different shaped beaks. Darwin’s theory was incomplete because it didn’t include a reliable mechanism for generating change.

Fast forward a hundred years or so, and we have demonstrated that the biology of an animal is due to the structure of its DNA, and that changes in that DNA change the biology of the animal. Using this ‘theory’, this model, we have inserted changes into DNA strings, changes that appeared as changed biology — as predicted. This is how we got Roundup resistant crops. Anyone proposing an alternative theory will have to account for glyphosate-tolerant soybeans.

So, at the present time, the genotype->phenotype, DNA->biology, model has shown no internal inconsistencies, and has been demonstrated to work at the most practical level. In order for the modern Theory of Evolution to be overturned, a new theory (Midichlorian Theory?) would have to be developed that would have both those characteristics, and make better predictions.

That covers the modern day applied Theory of Evolution. What about evolutionary predictions about the future? What about our view of how evolution worked in the past? Stay tuned.

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One Response to “God Hates Shrimp – Part 1”

  1. God hates shrimp – part 2 « FoundOnWeb Says:

    […] FoundOnWeb Changing the world is just something you do « God Hates Shrimp – Part 1 […]

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