East Asian communities may have to thank the environment because this is what prevented them from becoming alcoholics, a Yale University study has said.
It is a known fact that that many Asians carry variants of genes that help manage alcohol metabolism. Some of those genetic variants can make people feel uncomfortable, sometimes even ill, when drinking small amounts of alcohol.
As a result of the prevalence of this gene, many communities in countries like China, Japan and Korea have low rates of alcoholism.
Previous studies led by Kenneth Kidd, professor of genetics, psychiatry and ecology and evolutionary biology had provided evidence that recent natural selection in East Asia had caused one particular variant of the alcohol-regulating gene to become common.
In the present study led by Hui Li and researchers from Kidd's team, they studied the variant in the DNA of individuals in many different population groups in several more East Asian countries.
They discovered that the gene variant became widespread through natural selection in only some of those East Asian populations, particularly Hmong- and Altaic-speaking groups.
Scientists said that the genetic clues suggest that something was different in the environment of those populations and that the genetic difference assisted survival in that environment, though they still not identified that environmental difference.
However they believe that the genetic change could be triggered by any number of factors, like emergence of some new parasite.
Kidd believes that it is "just a serendipitous event'' of evolution that has restricted these populations from becoming alcoholics.
"What this finding does is highlight that something important in recent human history has affected the genetic composition of many East Asian populations," he said.
Kidd's team studied a gene variant known as ADH1B that code for alcohol dehydrogenases, enzymes that help in metabolism of alcohols, including ethanol and protect individuals from carrying them against alcoholism.
He said that lower rates of alcoholism in many of the Asian communities might well be due to cultural as well as genetic causes.
The study appears in April 2 issue of journal PloS One.