Inglehart et al. (2008) report the same finding: the main predictor of happiness differences across nations is the feeling of freedom of choice. These authors go a step further in their analysis. They find that, at the national level, this sense of freedom is a function of national economic development, democratization, and increasing social tolerance. This suggests that the distal predictors of national differences in happiness are two strongly correlated variables: national wealth and the rule of law. However, this argument cannot explain why the highest percentages of very happy people in the WVS are consistently found in northern Latin America and West Africa (Nigeria and Ghana).
An alternative explanation is provided by van de Vliert (2009). This author recognizes the association between national wealth and SWB, but analyzes climatic factors as well, such as harshness of summers and harshness of winters. From the perspective of this theory, people from poor societies in geographic areas that do not have excessive climatic variation are likely to be happier than people in poor societies with excessive climates. Van de Vliert’s theory thus may be able to explain the happiness paradox of Latin America and West Africa. However, his explanation of the relatively high happiness of Scandinavians is less convincing.
We find that national percentages of very happy people across the three latest WVS waves (2000–2004, 2005–2009, 2010–2014) are consistently and highly correlated with national prevalence of the rs324420 A allele in the FAAH gene, involved in the hydrolysis of anandamide, a substance that reportedly enhances sensory pleasure and helps reduce pain.