Texas State Board of Education Chairman Don McLeroy has argued repeatedly that natural selection — he calls it “unguided natural processes” — doesn’t account for the diversity of life today. He also insists that understanding evolution isn’t really important to the study of the biological sciences.
Well, Chairman McLeroy, meet the “swine flu.” Wendy Orent, author of “Plague: The Mysterious Past and Terrifying Future of the World’s Most Dangerous Disease,” explains why understanding natural selection and evolution is critical to understanding disease.
(U)nraveling all of this flu’s mysteries will take time. But, using the lens of Darwinian evolution, certain aspects are starting to come into focus. For one thing, it’s clear that the virus, which originated in Mexico, is most virulent in that country. The 1,000 or so reported Mexican cases have been either fatal or severe enough to require hospitalization. But because of natural selection, the strains spreading across the world are milder.
According to evolutionary biologist Paul W. Ewald of the University of Louisville, human influenza is usually a mild to moderate disease because it depends on host mobility to spread. The U.S., Canadian and New Zealand teenagers on their spring breaks did not sit in hospitals with the very sick and dying; they mingled with people who were sneezing and coughing but walking around, riding subways, perhaps going to the beach or dancing in nightclubs. People don’t start being really infectious until they show symptoms, and whatever symptoms those people had must have been mild enough to remain out in public. The strains sent out around the world were, by definition and necessity, milder than the most lethal strains.
Orent writes that understanding evolution helps health specialists and researchers predict what will happen in the future with this and other diseases. And, she says, understanding natural selection’s role in evolutionary processes helps us put what’s currently happening in perspective.
People died in Mexico because they were close to the epicenter of the disease, to the probable emergence of lethal strains from crowded pig breeding. But natural selection’s corrective action is swift and predictable: The strains spreading across the world are milder.
You can read the full piece here. We hope Texas state board members will take the time to do that.
