National intelligence and suicide rate: an ecological study of 85 countries

According to de Catanzaro’s (1981) evolutionary theory of human suicide, a threshold intelligence is necessary for suicidality. Intelligence and suicide mortality should thus be positively related. This prediction was tested and confirmed in an ecological study of 85 countries. National IQ was significantly positively related to the national male and female suicide rate. The relation was not attenuated when countries’ per capita Gross Domestic Product and the type of national IQ estimation were controlled. The relation was still positive, though not statistically reliable, when three further indicators (rates of the divorced, aged, and unemployed), salient for suicide rates and available for a subset of 36 countries, were additionally partialed out. Further evidence for a positive relation of intelligence and suicide mortality is provided by the observation of excess suicide prevalence in the Terman Genetic Study of Genius sample, relative to the general population.