In January, Bryan Caplan supported "Claim #1: One of the main causes - if not the main cause - of economic, cultural, and other forms of success is genetic," but argued against "Claim #2: Policy-makers can make their societies more successful by improving the quality of their societies' genes." His argument was a simple application of comparative advantage: on the margin, more people, even more dim people, increase a society's productivity by freeing up more bright people from dim tasks.

Randall Parker begs to differ.

• Low IQ immigrants will inevitably lower the living standards of higher IQ natives by lowering incomes, raising taxes, raising crime, and lowering the quality of government.
• Low IQ immigrants will pull higher IQ people away from creative design, engineering, and science work.
• Therefore one result of an influx of lower IQ immigrants will be to slow the rate of technological advances. This will delay technological advances which are the only hope for that half of humanity that have IQs below 90.
• One obvious piece of evidence for my argument can be seen from the incomes and occupations of higher IQ people in lower IQ countries.
• Another obvious piece of evidence is found in the steepness of the slope of lines in charts of national per capita GDP versus IQ. The slopes of graphs of per capita GDP versus IQ are even getting steeper with time. The steeper the slope the wronger the Benthamites.

Parker goes on to make the (relatively) obvious claim that evenly distributing the bright people amongst the nations would lower world GDP. Indeed, Innovators need collaborators and institutions to support them.

Do read all of Caplan's post and Parker's post. I'm inclined to agree with Parker, except that it's not clear what happens at the margin. If a society already has a lot of dim members, then how do the relevant economies of scale play out?