Tag Archives: cognitive function

Cognitive Function and our Genetic Code

Courtesy of Razib

Developing Intelligence : 99% Genetic? Individual Differences in Executive Function Are Almost Perfectly Heritable
Your ability to control thought and behavior relative to your peers – a set of capacities known as “executive functions” – is almost entirely genetic in origin, according to a newly in-press paper from Friedman et al. Over 560 twins completed tests to measure fundamental components of these executive functions, and the results were analyzed in terms of how similar identical twins performed to one another relative to fraternal twins (all twins in the study were reared together). Astonishingly, the results show that the variance common to all executive functions is correlated roughly twice as much between identical twins as between fraternal twins, and that individual variance in executive function falls directly in line with what would be expected from a perfectly heritable trait.

Furthermore, Friedman et al. integrated measures of general intelligence (“g”, estimated through the WAIS IQ test) and perceptual speed (essentially the speed with which subjects can complete very simple tasks) to show that the genetic contribution to executive function is not completely explained by genetic contributions to those more commonly-studied abilities. This is consistent with previous work showing that IQ is only moderately heritable (with 50-70% of variance explained due to genetic factors, far short of the 99% explained here).

99.9% is huge. The only study I can remember that came close is one of the studies that found working memory is 96% correlated with g. The conclusion that study and others received is that working memory was g. If the 99.9% number holds up for this study, then it will be accurate to say that executive function is genetically determined.

Fun stuff, and doubtless some serious money here for the pharmaceutical industry. True social equality looks like it will have to wait until gene therapy (Eugenics While You Wait(TM)) becomes common.