BBC Radio 4 has just concluded an excellent three-part series on the controversies over the genetics of intelligence and it’s one of the best and most nuanced discussions you’ll hear about the topic for many years.
The series is called Intelligence: Born Smart, Born Equal, Born Different and it’s carefully put together, wide in scope and doesn’t shy away from either tough science or difficult issues.
The only point I’d make about is one of context: most of the discussions apply to Western populations. This is not a point about race but one about environment.
Calculating heritability for a particular trait, in this case for cognitive function, involves working out how much of the difference between people is accounted for by genetics and the environment. But the result only holds for similar populations in similar environments.
For example, malnutrition, disease and high levels of environmental neurotoxins (e.g mercury from illegal gold mining) have a massive impact on cognitive function in kids and are clearly all environmental, rather than genetic, contributors to cognitive function.
But when most of these studies are done, these serious environmental effects have been screened out either explicitly (for example, by not including people who have pre-existing damage through neurotoxins in the study) or implicitly (because, for example, malnutrition barely exists where most heritability of intelligence studies are done).
The qualified conclusion is that general cognitive function is largely heritable when the most significant environmental effects on cognitive function have already been removed. This would be true for many European kids, for example, but much less so for kids from, let’s say, South Sudan.
The programme doesn’t claim otherwise, and lucidly describes how heritability is population specific, but it’s worth bearing in mind how much of the subsequent discussion addresses issues more relevant to the developed world than the one fifth of the world’s population who live in extreme poverty.
Either way, if you want to get up to speed on the debate about intelligence, cognitive function and genetics, the BBC Radio series is an excellent place to start and you’ll come away much smarter as a result.