THE ROLE OF NUTRITION IN SECULAR INCREASES IN INTELLIGENCE

In a number of economically developed nations the intelligence of the population has increased by approx. 1 standard deviation (SD) over the last half century. No satisfactory explanation for this increase has yet been forthcoming. In this paper it is argued that the major causal factor is improvements in nutrition. These have led to parallel increases in height, head circumference and brain size, and to improved neurological development and functioning of the brain. These are responsible for higher intelligence. Nutrition is still suboptimal for substantial proportions of the population and further increases in intelligence can be anticipated if standards of nutrition could be improved. © 1990.