Dec
29
2005

Evolution in action, and other breakthroughs of 2005

The journal Science has named a few studies that followed evolution in action--in influenza viruses, chimpanzees, and stickleback fish--"Breakthroughs of the Year."

Science Blog explains the significance of these studies, and the rest of the "top ten" science achivements of the year.

Your Comments, Thoughts, Questions, Ideas

Anonymous's picture
Anonymous says:

I just read the Evolution in action, and other breackthroughs of 2005, and I am having difficulty understanding how that proves the evolution theory. Could you please explain it to me? That would be very,
very helpful. Thank you!

posted on Thu, 12/29/2005 - 8:11pm
Gene's picture
Gene says:

Excellent question! The answer hinges on how we define the terms "prove," "theory," and "evolution."

"Theory," as we have explained in other threads, means something very specific in science. A theory is the best explanation for the available evidence. If I see someone walk in the office door, soaking wet and shaking an umbrella, I will develop the theory that it is raining outside. This is not just a wild guess; it is based on the evidence I see. (And I can test that theory by looking out the window.)

"Evolution" can also mean several things. In science, it can mean the big idea--that all life descended from a common ancestor. It can mean the process of that descent--natural selection, gene mutation, etc. (This is probably the most common definition, and I believe it's what the article was mostly referring to.) And it can mean the pattern of that descent--what species descended from what other species, and when.

Finally, "prove" also has several meanings. In law, it means to show that a given explanation is not only likely, but that all other explanations are unlikely. (My wet friend may have been soaked by a sprinkler, or she may have just stepped out of the bath. In order to prove my case, I would not only have to provide evidence that she was outside when it was raining, but also show that the other explanations are unreasonable.) This is pretty close to what "prove" means in science.

In Math, "prove" means to show that the answer you get is the only possible answer, given the rules we have to work with. 1 + 1 always equals 2. Of course, the natural world doesn't run by simple, unbending rules. People sometimes err by insisting that science provide ironclad, mathematical proof. But science doesn't work that way. Science always acknowledges that there is more to discover. Proof is based on what we know now, but we may learn something new tomorrow. (Perhaps my friend was splashed by a passing car. That new explanation would have to be consistent with the evidence we already have.)

"Prove" can also mean to demonstrate--"you don't think I can jump 10 feet? Watch, I'll prove it to you!" I believe the article was using the word "prove" mostly in this sense.

OK, so what about this article? It talks about a lot of discoveries in animal genetics. How does this prove evolution?

In simple terms, modern evolutionary theory goes something like this:

  • Animals' bodies are built by their genes
  • Animals inherit their genes from their parents, and pass them on to their children
  • On rare occasions, genes also change, or mutate
  • If an animal has a gene that gives its body an advantage, that animal is more likely to survive and have children--children which will also have that gene.
  • Over time, genetic changes will accumulate in a population until their bodies are so different, they are a new species.

The first three items are known facts. The last two are predictions based on those facts.

So, if the theory of evolution is true, then we ought to see certain things happening. We ought to see genetic changes start to accumulate in different populations before they become two separate species. And that is exactly what we see in the European blackcaps.

If the theory of evolution is true, we ought to see genetic changes accumulate in populations with different behaviors. And that is exactly what we see in the European corn borers.

If the theory of evolution is true, we ought to see populations with different behaviors remain separate, even if they are put in the same place. And that is exactly what we see with the Hawaiian crickets.

If the theory of evolution is true, then different species which all descended from a single ancestor, and whose bodies changed in the same way, should also show similar genetic change. And that is exactly what we see with the stickleback fish.

If the theory of evolution is true, then DNA that is important to survival should change less radically than DNA that is not so important. And that is exactly what we see with the fruit flies.

And so on. I suppose these discoveries are no more or less important than a thousand others that also demonstrate evolution in action. But in 2005, scientists got better and better at studying genes, producing a whole new body of evidence proving that evolution works.

posted on Tue, 01/03/2006 - 5:59pm
Shanea's picture
Shanea says:

I like the thoughts and theories on Evolution in Action. I can not seem to find any scientists names on who contributed to it though. What were a few of the scientist’s names?

posted on Fri, 01/12/2007 - 8:19pm

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