Cranial size and IQ in Asian Americans from birth to age seven

Abstract

The Collaborative Perinatal Project is a longitudinal study of over 53,000 children followed from birth to 7 years. Up to now, studies have analyzed data on the 17,000 European American children and the 19,000 African American children. Here data are reported and analyzed for a sub-sample of 100 Asian Americans. The Asian sub-sample averaged a higher IQ (110) at age 7 than did the white (102) or the black sub-samples (90). At birth, 4 months, 1 year, and 7 years, the Asians averaged a larger cranial capacity than did the whites or blacks despite being smaller in stature and lighter in weight (at age 7, Asian z scores from -0.20 to -0.40 in height and weight). Head circumference (or cranial capacity) at birth correlated .46 with head circumference (or cranial capacity) at age 7 which correlates .21 with IQ test scores at age 7. The Asians also averaged a higher parental socioeconomic status at birth than did the whites or blacks (Asian z scores = +0.41 and 1.27 respectively). Socioeconomic status related to cranial capacity and to IQ scores but not to stature or to weight, neither of which correlated with IQ. Males averaged larger body and cranial sizes than did females (and, by 12 months, larger cranial sizes even after correction for body size).