Jerry Coyne asked …

… and I complied.  I made a long reply to his most recent post because it related to something that I had said in other comments and that people had taken me to task for.  He asked me to move it to my blog.  So, I will.

His original post is here:  http://whyevolutionistrue.wordpress.com/2010/06/24/natural-selection-in-humans-the-epas1-gene-at-high-altitudes/

My comment was this:

At the risk of people accusing me of being a troll or thread-jacker, I’ll move my comments on human intelligence interrupting evolution here.

See, while this is interesting, it also allows me to clarify my point, which was that intelligence and tool-making ALLOW humans to interrupt evolution by choosing what impacts them. Let’s look at the impacts of the EPAS1 gene:

“but can also cause excessive production of red blood cells, leading to chronic mountain sickness that can kill people or reduce their reproduction. Some mutations in EPAS1 that increase its expression, for instance, are associated with increased hypertension and stroke at low altitude, symptoms similar to that of mountain sickness.”

But if you look at the effects, particularly hypertenson and stroke, those can, in fact, be treated with drugs. So someone that has those additional side effects might be able to live perfectly well and reproduce perfectly well simply by taking drugs to reduce hypertension, and other things to reduce the risk of stroke. If there are enough of these, there wouldn’t be ANY significant statistical difference caused by those extra factors; people with the hypertension and stroke risks from the EPAS1 gene expression simply wouldn’t die or reproduce statistically significantly less than those that didn’t have the gene or the added risks from it. Thus, those selective factors end up going away, because we filter them out and correct for them.

The same thing can be said for the differences in high and low altitude. It is, in fact, theoretically possible for us to invent a drug that someone can take to increase red blood cell production when at high altitudes and reduce it at low altitudes (it might not be the same drug). So, then, people who don’t naturally have increased red blood cell production can simply take the drug and in fact have that — temporarily, while in the environment that needs it. And those who have the increased production, when coming down to lower altitudes, can take the drug to reduce it. Thus, as long as the drug is readily available and has no other significant side effects (which rarely happens), there’s no difference selectively between those who have the EPAS1 gene and those who don’t. Or, rather, there ARE differences, but no selective factor can select on them since humans control for it.

Now, you’re correct that practically selection will work on us for quite some time because we don’t correct for everything and can’t correct for extremely drastic changes that we aren’t ready for. So, as I said elsewhere, the big things and the little things will always count. But we interrupt evolution in a signficant sense using our intelligence and our tools, and I just want to make sure that that is properly recognized.

Feel free to discuss …

EDIT:  Coyne deleted my last comment, which essentially said that what he claimed in the comment that asked:

“You’ve got your own blog, so could you post these long comments over there? I’m not going to point out your many misconceptions, including the fact that mountain sickness can be successfully treated at high altitude, or that drugs are always completely successful at reducing hyptertension.”

misread my comment, since I never claimed that mountain sickness can be treated at high altitude — I never mentioned it at all, and at best said that in theory we could create a drug to increase or decrease red blood cell production as required — and never claimed that drugs are always completely successful at reducing hypertension — I said that it can reduce it so that the differences are not statistically significant.  I also added an I admit harsh statement that he should be careful about his own misreadings before criticizing mine.  So, since I had also said that that might be my final comment … well, it looks like it is.  At least there.

I’ll write a new post on that one.

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