The biggest canard that one typically hears from creationists or advocates of so-called “Intelligent Design” is that there is no “proof” for the theory of evolution. In the sense that no one has observed the evolution of a species over millions of years this is true. However, as this article in today’s Washington Post details the central tenants of evolutionary theory have been proven and replicated in laboratories across the world.
When scientists announced last month they had determined the exact order of all 3 billion bits of genetic code that go into making a chimpanzee, it was no surprise that the sequence was more than 96 percent identical to the human genome. Charles Darwin had deduced more than a century ago that chimps were among humans’ closest cousins.
But decoding chimpanzees’ DNA allowed scientists to do more than just refine their estimates of how similar humans and chimps are. It let them put the very theory of evolution to some tough new tests.
If Darwin was right, for example, then scientists should be able to perform a neat trick. Using a mathematical formula that emerges from evolutionary theory, they should be able to predict the number of harmful mutations in chimpanzee DNA by knowing the number of mutations in a different species’ DNA and the two animals’ population sizes.
“That’s a very specific prediction,” said Eric Lander, a geneticist at the Broad Institute of MIT and Harvard in Cambridge, Mass., and a leader in the chimp project.
Sure enough, when Lander and his colleagues tallied the harmful mutations in the chimp genome, the number fit perfectly into the range that evolutionary theory had predicted.
Science is a process of making a hypothesis and then attempting to either prove or disprove it. Evolution is science precisely because it makes predictions that can be tested and proven to be either true or false. In this case, the prediction was shown to be true —- which is a strong argument in favor of the evolution as a theory of human and species development.
By contrast, said Alan Leshner, chief executive of the American Association for the Advancement of Science, Intelligent Design offers nothing in the way of testable predictions.
“Just because they call it a theory doesn’t make it a scientific theory,” Leshner said. “The concept of an intelligent designer is not a scientifically testable assertion.”
Asked to provide examples of non-obvious, testable predictions made by the theory of Intelligent Design, John West, an associate director of the Discovery Institute, a Seattle-based ID think tank, offered one: In 1998, he said, an ID theorist, reckoning that an intelligent designer would not fill animals’ genomes with DNA that had no use, predicted that much of the “junk” DNA in animals’ genomes — long seen as the detritus of evolutionary processes — will someday be found to have a function.
(In fact, some “junk” DNA has indeed been found to be functional in recent years, though more than 90 percent of human DNA still appears to be the flotsam of biological history.) In any case, West said, it is up to Darwinists to prove ID wrong.
Claiming that it is up to your opponents to prove your theory wrong is a sign of someone not concerned with science at all.
But chimpanzee DNA is not the only evidence in favor of evolution. Consider this:
Richard E. Lenski, a biologist at Michigan State University, has been following 12 cultures of the bacterium Escherichia coli since 1988, comprising more than 25,000 generations. All 12 cultures were genetically identical at the start. For years he gave each the same daily stress: six hours of food (glucose) and 18 hours of starvation. All 12 strains adapted to this by becoming faster consumers of glucose and developing bigger cell size than their 1988 “parents.”
When Lenski and his colleagues examined each strain’s genes, they found that the strains had not acquired the same mutations. Instead, there was some variety in the happy accidents that had allowed each culture to survive. And when the 12 strains were then subjected to a different stress — a new food source — they did not fare equally well. In some, the changes from the first round of adaptation stood in the way of adaptation to the new conditions. The 12 strains had started to diverge, taking the first evolutionary steps that might eventually make them different species — just as Darwin and Wallace predicted.
Or this:
[G]enome sequencing projects have shown that human beings, dogs, frogs and flies (and many, many other species) share a huge number of genes in common. These include not only genes for tissues they all share, such as muscle, which is not such a surprise, but also the genes that go into basic body-planning (specifying head and tail, front and back) and appendage-building (making things that stick out from the body, such as antennae, fins, legs and arms).
As scientists have identified the totality of DNA — the genomes — of many species, they have unearthed the molecular equivalent of the fossil record.
It is now clear from fossil and molecular evidence that certain patterns of growth in multicellular organisms appeared about 600 million years ago. Those patterns proved so useful that versions of the genes governing them are carried by nearly every species that has arisen since.
These several hundred “tool kit genes,” in the words of University of Wisconsin biologist Sean B. Carroll, are molecular evidence of natural selection’s ability to hold on to very useful functions that arise.
The scientific evidence in favor of evolution is clear. Meanwhile, neither creationism nor ID can withstand the rigors of the scientific method. This shouldn’t even be a subject of debate in the 21st Century and yet, thanks to willful ignorance and the appalling state of science eduction in this country, it still is.
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