London, Jan 15 (IANS): Presence of a gene variant involved in sensory pleasure and pain reduction may contribute towards making a population happier than others, suggests new research.

"The citizens of nations which rate themselves happiest display a specific genetic feature: their DNA is more likely to contain a specific allele involved in sensory pleasure and pain reduction,” said Michael Minkov of the Varna University of Management in Bulgaria.

The researchers weighed up genetic and various external factors that might contribute to national differences in happiness. 

The researchers used data from World Values Survey (2000 - 2014) that consists of nationally representative surveys on beliefs, values and motivations of people conducted in almost 100 countries. 

They calculated the average national percentages of respondents who unambiguously reported being "very happy". 

Their calculations also included population genetic data from an allele frequency database maintained by population geneticist from Yale University as well as climatic information about the harshness of summers and winters, the historic prevalence of pathogens and World Bank economic data, since national differences in subjective well-being are thought to depend on socioeconomic and climatic factors in addition to genetic factors.

The authors found a strong correlation between a nation's happiness and the presence of the A allele in the fatty acid amide hydrolase (FAAH) gene variant rs324420 in its citizens' genetic make-up. 

This allele helps prevent the chemical degradation of anandamide, a substance that enhances sensory pleasure and helps to reduce pain, the researchers explained.

Nations with the highest prevalence of the A allele are quite clearly also those who perceive themselves happiest, the study said.

The findings were published in Springer's Journal of Happiness Studies.