Desise and overpopulation is questionable. Severe overpopulation often leads to desiese. Drugs and alchahol can weaken the immune system, which would be detrimental to survival under those circumstances. Our bodies are amazingly clever, and would probably recognize that weakening the immune system in the presense of a deadly disese is tantamount to suicide.
Evolution doesn't "choose" the better way, the ways that don't work get eliminated, leaving the ways that worked. It's thought the alcoholism gene is a leftover of whatever mechanism helps survival in times when populations come under stress.
For an easy example to help make sense of it, look at your average homeless drug addict. Often times they suffer from skin diseases and cancers and other serious ailments that would kill or completely immobilize a healthy person. Alcoholism, or whatever is behind it, makes a person much more resistant to harsh environments. That's how the theory goes at least. I'll try to find some sources that explain it more scientifically than I ever could. I'm not arguing that alcoholism is good for humans. For the individual, alcoholism is just like any other disease, detrimental to the organism. For the population however, it may help the species. The idea is, keep an organism alive so it can breed, even at the health of that organism.
Interesting points. Could we make a distinction between highly stressful addiction, for instance those in the trenches of WWI, and addiction due to boredom, such as a perfectly easy living middle class teenager injecting smack? The second must be different to stress induced addiction.
We're talking much longer time scales. More than one generation type timescale. What is happening in Russia is the leftover alcoholics in the gene pool who haven't died off and bred themselves out yet.
Anywhere in the world where you have had extended periods of famine, war, disease, or other factors, you will find high levels of alcoholism in the genetic pool. As those societies come out of the periods of duress, the alcoholic gene will die off. It's not healthy for an individual to carry the disease in it's active state. Which is where modern man comes into play, because of our increased health and medicine systems as a society, it takes longer for the alcoholic gene to die off through generations, if we're even allowing it to die out at all anymore.
The scary aspect of this theory is that as we advance as a species, we have been putting more and more effort into helping the alcoholics and other diseased. While I completely agree with the fact we should continue to help those who need it, you have to wonder, are we hurting the human species by not only allowing, but helping the genetically weak survive? No other animal species on earth other than humans is capable of going against Mother Nature's (and/or God's) evolutionary rules. (for a simple example, the more we take antibiotics, the more bacteria are able to resist them. Or when hygiene became more prevalent in Europe, we lost our resistance to some diseases)
