On Dec 17, 2013, at 1:01 PM, Christopher Green wrote: > My understanding is that here, as in the intelligence debate, proportions of > variance attributable to "heredity" are only valid for a given level of > variance in the environment. Restrict the range of variability in the > environment and "heredity" goes up. Increase the variability of the > environment and "heredity" goes down. In short, it can be a highly misleading > statistic unless the environment is somehow artificially "standardized."
Yes, that was the point I was trying to make with my example. I have never really understood the fascination with heritability estimates. They were developed primarily for agricultural purposes (if I remember correctly: it's been a long time since I studied the history of this area) because knowing the proportion of additive genetic variance to total phenotypic variance helps us to estimate responses to artificial selection. However, even when heritability is zero, genes will still be important contributors to the development of a trait. A heritability of zero simply means that genetic variance is not associated with phenotypic variance. This will occur, for example, when directional selection (or genetic drift) has led to the fixation of genes important for the development of a trait. And there are many other complexities that enter into interpreting heritability. For me, it was useful simply for showing that there were genes in a population that we might want to take a look at. Understanding how these genes were important for the development of a phenotype (i.e., describing gene-environment interactions and epigenetics) was always the goal. I never got very far in this line of work, but many others have since then. Best, Jeff -- --------------------------------------------------------------------------------- Jeffry Ricker, Ph.D. Professor of Psychology --------------------------------------------------------------------------------- Scottsdale Community College 9000 E. Chaparral Road Scottsdale, AZ 85256-2626 Office: SB-123 Phone: (480) 423-6213 Fax: (480) 423-6298 --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=31543 or send a blank email to leave-31543-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
