Mankind Quarterly, Vol. 46, No. 3 (Spring 2006)
pp. 273-312

Determinants of Mental Ability on a Caribbean Island, and the Mystery of the Flynn Effect
Gerhard Meisenberg, Elliott Lawless, Eleonor Lambert, and Anne Newton

On the Caribbean island of Dominica, mental test scores have risen by approximately 1.2 standard deviations (18 IQ points) over the past 35 years. In this paper we relate this secular trend to some of the social, educational and material conditions that could conceivably affect mental ability. We find that measures of formal schooling are the strongest correlates of IQ in both the older and the younger generation. Since secular IQ gains coincided with a major expansion of the school system, we propose that advances in formal education are a major cause for the rising IQ in Dominica. Family structure has a minor influence on IQ, and is unrelated to the generational IQ gain. Also family size is not an important variable. Measures of parental socioeconomic status are only mildly related to intellectual outcomes in both the older and the younger generation, and explain only 10% of the generational IQ gain. Neither generational increases in height and head circumference nor changes in the consumption of different types of food during childhood can explain a significant fraction of the generational IQ gain. These physical measures are only marginally related to IQ in either age group. A large portion of the generational IQ gain remains unexplained.