Have Europeans evolved to be fat depressed alcoholics?

Have Europeans evolved to be fat depressed alcoholics?

As levels of obesity and binge drinking continue to soar in Europe, Scottish researchers have discovered Westerners may be genetically programmed to consume fatty foods and alcohol with a greater appetite than those in the East.

Scientists at the University of Aberdeen have uncovered a genetic ‘switch’ which they believe makes Europeans far more likely to opt for high-fat food and alcohol than those in Asia.

Their findings – which also have implications for the treatment of depression – could ‘open up a world of new therapy options’ for what is rapidly becoming the ‘plague’ of the Western world.

Scientists at the University’s Kosterlitz Centre compared the DNA of humans to that of mice and birds and found a genetic ‘switch’ also known as an enhancer, that has remained unchanged for 300 million years.

This ‘switch’ – a piece of DNA which turns genes on or off within cells – controls the galanin gene, which, when turned on in an area of the brain called the hypothalamus, regulates appetite and thirst.

Dr Scott Davidson, a native of Peterhead who found the ‘switch’ said: “There are 25,000 genes in every cell and these are nearly identical in all mammals - what makes us different from other species, and from each other, is when, where and by how much each of these genes are turned on or off during our development as embryos and in our lifetime.

“Not all cells turn on all genes all at once – something organises which genes are turned on in different cells and we call them enhancers or switches.”

The team, led by Dr Alasdair MacKenzie, also noticed that the ‘switch’ was different in some people and when they compared different racial groups they found that it had mutated and was weaker in 16 per cent of Europeans and 30 per cent of Asians.

Dr MacKenzie said: “The switch controls the areas of the brain which allows us to select which foods we would like to eat and if it is turned on too strongly we are more likely to crave fatty foods and alcohol.

“The fact that the weaker switch is found more frequently in Asians compared to Europeans suggests they are less inclined to select such options.

“These results give us a glimpse into early European life where brewing and dairy produce were important sources of calories during the winter months.  Thus, a preference for food with a higher fat and alcohol content would have been important for survival. The negative effects of fat and alcohol we see today would not have mattered so much then as life expectancies were between 30-40 years.

“It is possible that during the winter individuals with the weaker switch may not have survived as well  in Europe as those with the stronger switch and as a result those in the west have evolved to favour a high fat and alcohol rich diet.”

The study, published in the respected Journal of Neuropsychopharmocology, also found that changes in the same ‘switch’ were linked to depression.

Dr MacKenzie added: “Galanin is also produced in an area of the brain called the amygdala where it controls fear and anxiety. Thus, changing levels of galanin in the amygdala will have an effect on an individual’s emotional state. Intriguingly, the switch was also active in the amygdala.

The Aberdeen scientists worked alongside a team based in the Institute of Psychiatry in London led by Prof Peter McGuffin who recently conducted genetic studies on thousands of depressed patients.

“This study showed that the galanin gene is linked to depression and we show that part of a gene which is linked to depression is strongly linked to our switch.” Dr MacKenzie added

In addition to the genetic studies his team has started to pick apart the machinery that control the switches.

Dr Davidson said: “This has already allowed us to identify potential drug targets that will be used to develop a whole new generation of antidepressants as well as drugs to reduce cravings for fatty food and alcohol.”.

Professor Ruth Ross, Head of the Kosterlitz centre was delighted with the findings of the project and said: “It is now becoming obvious that the majority of the information in our DNA required for health does not reside in genes but in the vast uncharted areas of our DNA which tell the genes what to do”.

“This study represents a major advance in our ability to understand how human genetic variation within this huge, murky and unexplored region of DNA contributes to disease susceptibility and places the University of Aberdeen at the very forefront of the field”.

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