
Originally Posted by
Laramie Hartmann
Many experts in the field do believe in the usefulness and validity of IQ testing. The tests have been developed to eliminate cultural and environmental factors as much as possible. Twin studies are just one of the methods used to prove the validity of IQ testing. I can agree that there may be some unintended bias, but that doesn't render testing ineffective. High test scores strongly correlate with many factors that most consider positive, such as high income, low criminality, and marital stability.
Why would you believe that selective evolutionary pressures wouldn't select for higher intelligence in certain populations? We were able to breed dogs with specific traits in just a few hundred years; humans have had far longer for variance to develop, and intelligence is an incredibly useful trait, especially in unforgiving climes.
To your point on hip displasia, you're correct that phenotypic expression for an individual cannot be perfectly predicted from genetic sequencing, but accurate predictions on group outcomes can be made.
They're not everything, but genetic differences between populations are important factors to look at when considering the causes for various group outcomes.