Behavior geneticists

The origin of most myths about IQ is the field of American behavior genetics. Psychometrics refers to the construction and application of psychological tests (for example, the IQ test), while behavior genetics is a field of study concerned with the genetic basis of animal and human behavior. Not all behavioral geneticists use psychometric tools, and not all psychometricians (people who construct and apply psychological tests) are... 

There s another important difference in the approach to heritability between biology and behavioral genetics. Biologists are usually interested in how well a trait will respond to selective breeding, while behavioral geneticists have been focused on how much of a trait is determined by genes.8... 

So what is the crude approximation here In general, the heritability calculation of behavioral geneticists assumes a linearization of an ill-defined nonlinear function relating phenotype variance to gene-derived variance, environment-derived variance, and an assortment of partial interactive variances from various sources. The linear approximation considers the total phenotypic variance to be simply the sum of variance due to heredity plus the variance due to environment. Heritability is the proportion of phenotypic variance due to genes, so according to the linear model heritability plus the proportion of variance due to environment must always be equal to i.o. 

The clearest refutation of the idea advanced by hereditarian behavior geneticists that the prenatal environment is of only small consequence for childhood and adult IQ is the research on known IQ effects of prenatal exposure to certain neurotoxins. Any argument that this neurotoxic impact is extreme, rare, and therefore irrelevant is unsound. In addition, every known neurotoxic effect confirms the possible prenatal impact of other environmental agents not yet studied, and we do know there are literally hundreds of such neurotoxins already dispersed in the environment.15... 

Some behavioral geneticists are beginning to understand that analysis of the impacts of environment on gene expression may be as important as the identification of genes associated with behavior. See Rutter, 2006, pp. 211—220. 

Helicoidally isotropic particles furnish the simplest examples of bodies manifesting screw-like behavior. These particles are isotropic, in that their properties are the same in all directions. Yet they possess a sense, and spin as they settle in a fluid. These ideas are likely to be of interest to microbiologists, biophysicists, geneticists, and others in the life sciences for whom handedness and life are intimately intertwined. The microscopic dimensions of the objects of interest to them insures ipso facto that the motion takes place at very small Reynolds numbers. Readers interested in an elementary but broad survey of sense in the physical and biological sciences are referred to Gardner s delightful book The Ambidextrous Universe (Gl). 

The nervous system lies between genes and behavior. In his Nobel Prize lecture in 2002, geneticist Sydney Brenner said, Behavior is the result of a complex, ill-understood set of computations performed by nervous systems. It seems essential to decompose the question into two one concerned with the question of the genetic specification of (different) nervous systems and the other with the way nervous systems work to produce behavior. .. We are drowning in a sea of data and starving for knowledge. 

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