Expert: Dana Krempels, Ph.D. - 5/29/2007

Question
what is the effect on the human gene pool of the discovery of expensive medical treatments that permit individuals with previously lethal phenotypes to live? should society permit research to find ways to treat more such conditions?

Answer
Dear Morgan,

You have two separate questions, each of which has a different type of answer.  The first one is strictly biological:  what has the effect of medicines been on the gene pool.

From a dispassionate perspective, one could say that it has increased the diversity of the human gene pool by allowing more different alleles (even ones that might have previously been maladaptive, or harmful) to remain in the gene pool when a lack of such medicines might have "weeded them out."

In the absence of medicines, many of these harmful alleles of normal genes would undoubtedly leave the gene pool.  But a trait is defined as "adaptive" (likely to increase your chances of leaving offspring), "maladaptive" (likely to decrease your chances of leaving offspring), or "neutral" (not likely to affect your chances of leaving offspring) depending on the environment in which an organism lives.  And now, medicines are a part of the human environment (at least in Western society.

So in effect, a trait that might have been extremely maladaptive, or even lethal in the past (say, congenital diabetes) might now be only mildly maladaptive, or even neutral if the sufferer is on the proper medications.  Natural selection doesn't have a value system.  It just works in the environment in which organisms breed and leave their genes.  So when the environment changes (e.g., with the addition of medicines to treat previously lethal conditions), so does the gene pool.

The second question is not a biological one, but an ethical one:  Should society permit research designed to treat lethal conditions?

This is a matter of opinion.  My own opinion is that it is a noble human endeavor to try to end suffering caused by genetic disease, or to try to find medicines to improve the lives of those who suffer pain and illness.  But with that ability comes a responsibility to know that without controlling our own population, we could overrun the earth and find ourselves in an overcrowded world where limited resources, not lethal disease, are the selective factors.

And that would be a very different type of cruel world.

I believe that the research should be permitted and encouraged, but that humans must stop treating their reproductive ability like some Sacred Cow that must not be questioned or curtailed.  

Something's got to give.  We must find ways to control our population before Mother Nature herself finds the way.  And believe me, population control by our own choice will be MUCH better than anything nature will throw at us.

Hope that helps.

Dana