Evolution Could Soon Protect Humans from Alcoholism

Alcoholism is a global problem. MEHDI FEDOUACH/AFP/Getty Images

Humans may be evolving a genetic variant that would make them physically unable to consume large amounts of alcohol, new research suggests. If this gene is able to take hold on the global population, it could one day help reduce alcoholism and alcohol-abuse related health ailments.

In a study published this week in Nature Ecology & Evolution, two researchers from the University of Pennsylvania looked at the genome of 2,500 people in 26 populations found on four continents to better understand how the human genome continues to change. The DNA information from these individuals was obtained via the 1000 Genomes project, the largest public catalog of human variation and genotype data, New Scientist reported.

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Our DNA is hereditary material that stands as the code for each individual person. DNA is gathered together in a specific sequence that further determines how hereditary information will be expressed in people.

A gene variant is when DNA sequence has been slightly altered so as to express a different behavior or physical feature. When this change happens in a single individual it is known as a mutation, but when this change is seen across a population, such as the first emergence of blue eyes in Europe, it is referred to as a gene variant. Variations that help humans survive are passed down to subsequent generations and those that hinder survival are often erased from our DNA.

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The duo specifically looked at genes that had both emerged recently and existed in various populations that did not seem to have much geographic contact. This allowed them to identify five gene variants that seemed to be on the rise in various areas of the globe. These variants were related to traits such as malaria resistance, testicle health, and heart disease prevention, New Scientist reported. However, one gene variant, the ADH variant, was of particular interest due to its effect on our ability to tolerate alcohol.

When we drink alcohol, our body is able to metabolize or break down the ethanol in our drink so that we can get the chemical out of our bodies as soon as possible. When we drink too much alcohol our bodies struggle to keep up with metabolizing the chemical. This causes too much alcohol to enter our bloodstream which is what causes the unpleasant effects of drinking, such as nausea.

According to the study, the ADH variant affects our ability to metabolize alcohol. Also, the exact mechanism is not yet clear, individuals with this variant would not be able to break down alcohol as well. As a result, even the smallest amount of alcohol would cause extremely unwell feelings and New Scientist reported that it is unlikely these individuals would be able to physically consume enough alcohol for them to develop alcoholism.

Study co-researcher Benjamin Voight of the University of Pennsylvania told Newsweek that previous research suggested that African Americans with this gene variant have a slightly reduced risk of developing alcohol dependence. "It is small but consistent," said Voight. Thus this genetic variant may act as a sort of protection against this alcoholism.

At the moment, the variant is seen sporadically throughout populations and has only been detected in East Asian and West African populations. It hasn't made any significant difference to human health and lifestyles, at least not yet. In addition, Voight emphasized to Newsweek that this gene variant would not act as a one-step solution to alcohol dependency.

"Alcohol dependence is a complex human trait—an individual's risk for alcohol dependence is a function of genetic background, environment, and behavior," said Voight. "So the contribution from this specific genetic change has to be viewed in the context of the myriad of other factors that perhaps contribute a lot more."

Rather, Voight told New Scientist that his research shows that genes can change in similar ways throughout global populations, and these changes may be an effort to help people adapt to changes in their ecologies.