BEHAVIORAL DIFFERENCES 293 



are similar in that emphasis may be placed alternatively upon the effects of a well- 

 defined genetic entity or upon the genetic contribution to the variance of a character 

 continuously distributed. The concept of thresholds which appear so important to 

 behavioral genetics is familiar to students of growth and was formally described by 

 Wright 1451 in his discussion of Polydactyly in guinea pigs. Thus the unique nature 

 of behavioral genetics lies predominantly in the need for more extensive and detailed 

 control of the life history of the subjects and of the use of special methods developed 

 by psychologists and animal behaviorists for the objective measurement of behavioral 

 patterns. 



DISCUSSION 



Dr. Burdette: Dr. Benson Ginsburg of the University of Chicago will open the 

 discussion of the paper of Dr. Scott and Dr. Fuller. 



Dr. Ginsburg: One section of the paper by Drs. Scott and Fuller should be empha- 

 sized by repeating it. "The preceding remarks point up a major difference in the 

 methodology of behavioral genetics, genotypic versus phenotypic orientation. In the 

 former, an investigator starts with a known genotypic difference and studies its effects 

 upon behavior. In such a situation a gene, a chromosome, or a whole genotype is 

 analogous to a treatment applied to an organism. The genotypically oriented in- 

 vestigator does not usually stop with demonstrating a correlation between genotype 

 and behavior. He is also interested in tracing the path between gene and character 

 through intervening physiologic mechanisms." I wholeheartedly agree with this 

 point of view and cite it as the reason that the Scott-Fuller paper really does belong 

 in a section devoted to physiologic genetics. 



My own view toward so-called behavioral genetics follows from this position: 

 behavior is a biologic aspect of organisms under genetic control and with an evolutionary 

 history. I do not think that I am any more or less of a geneticist since turning from 

 pigment studies to behavior. It is simply that one is studying another phenotype 

 belonging to a different and more fundamental aspect of organisms. I believe that 

 genetics occupies a central synthesizing position in the biological sciences and that it 

 contains the organizing principles for thinking about evolution; for thinking about 

 ontogeny; and for thinking about methods of investigating the ways in which organisms 

 come to be the way they are, both phylogenetically and ontogenetically, including 

 having the capacities to interact with each other. Physiologic genetics is thus involved 

 in the study of the capacities of the nervous system, the endocrines, and the way in 

 which all the capacities of the organism behave, including those making possible the com- 

 plexities of group organization, development, and interaction. 



At the level of the gene, genetics occupies the same central position in a broader 

 context. The new laws of physics and chemistry will probably come from a study of 

 these biomolecules, the genes, and the ways in which they are able to duplicate them- 

 selves and control cellular activities. In this manner, genetics occupies a very central 



