Intelligence: Are we getting smarter?

 作者:明则肪     |      日期:2019-03-01 04:17:00
By Linda S. Gottfredson Read more: “Instant Expert: Intelligence“ Over the past century, each successive generation has answered more IQ test items correctly than the last, the rise being equivalent to around 3 IQ points per decade in developed nations. This is dubbed the “Flynn effect” after the political scientist James Flynn, who most thoroughly documented it. Are humans getting smarter, and if so, why? One possible explanation is that today’s world supports or demands higher levels of intelligence. Flynn himself suggests that intelligence has risen in part because we view life more analytically, through “scientific spectacles”. However, the idea that cultural environments have potent and widespread effects on how smart we are does not square with what we know about the high heritability of intelligence. Environmental variation contributes relatively little to the IQ differences in a birth cohort as its members mature over the decades. How, then, could it create such big IQ differences across successive birth cohorts living in the same era? Another theory puts rising IQ down to physiological changes. In the past century human height has been increasing in tandem with IQ throughout the developed world. Better public health measures have reduced the need for our immune systems to consume resources to combat infectious disease, leaving us able to spend more on growth – and larger, smarter brains may be just one consequence. Not only that, as more people travelled and married outside their local group, populations may have benefited genetically from hybrid vigour. Inbreeding is known to lower intelligence,