Ebook: Biological Approaches to the Study of Human Intelligence

"Biological approaches to the study of human intelligence have been slow to develop and slower to gain acceptance. Yet, as the chapters in this volume demonstrate, much information about the underlying biological bases of intelligence has been amassed. That which is now known in this area is both intriguing and challenging to many traditional notions about the nature of intelligence. To be sure, some of the biological findings are based on small samples and require further study and attempts at replication. Others, however, rest on more solid ground and are sufficiently well-replicated that they deserve serious consideration in any future theories regarding the prime contributors to and causes of individual differences in mental abilities.
In Chapter 1, Hans Eysenck, a long-time advocate of the biological approach, draws parallels between psychology, biology, chemistry, and physics and argues for the need to place the measurement of intelligence, and theories of intelligence, on a more scientific basis. In his summary of research investigating the biological basis of intelligence, Eysenck mentions the study of evoked potentials, cerebral glucose metabolism, and the biochemistry of the brain, each of which is afforded a thorough and detailed discussion in the later chapters by Deary and Caryl (Chapter 6), Haier (Chapter 7), and Naylor, Callaway, and Halliday (Chapter 8), respectively.
Following Eysenck's chapter, Bouchard (Chapter 2) elucidates the roles of genetic, chromosomal, and environmental influences on intelligence, and Thompson (Chapter 3) describes the application of behavioral genetic designs to the study of cognitive development (including general and specific abilities, information processing, scholastic achievement, reading disabilities, and mental retardation) in infancy and childhood. Each of these two chapters provides a convincing demonstration of the value and potential of behavioral genetic methodologies.
In Chapter 4, Jensen and Sinha provide a comprehensive survey of virtually the entire literature on physical correlates of mental abilities in humans. The topics they discuss include height and weight; head and brain size measurements (including the very recent in vivo brain size study by Willerman, Schultz, Rutledge, & Bilger, 1991); physical growth rate; myopia; blood types and blood serum chemistry; and a variety of other less-studied physical features. Following this, in Chapter 5, Lynn discusses the effects of nutrition on brain growth and intellectual development and considers the possible contribution of nutritional changes to the large increases in intelligence that have been observed in several economically advanced nations over the past 50 years. He also suggests that nutritional differences may account for a significant proportion of the difference in the mean IQ scores of whites and blacks in the United States-a hypothesis which, if borne out and acted upon, could have immediate favorable consequences. Finally, Kimura and Hampson-in Chapter 9-consider sex differences in mental abilities and the neural and hormonal mechanisms which mediate these. Their chapter identifies a number of biological mechanisms that make substantial contributions not only to observed sex differences in cognition but also to individual differences within each of the sexes."