It's important not to overinterpret the _g_ factor as some unitary essence of intelligence rather than the length of a hyperellipsoid. It seems likely that [if you gave people a bunch of _physical_ tests, they would positively correlate with each other](https://www.talyarkoni.org/blog/2010/03/07/what-the-general-factor-of-intelligence-is-and-isnt-or-why-intuitive-unitarianism-is-a-lousy-guide-to-the-neurobiology-of-higher-cognitive-ability/), such that you could extract a ["general factor of athleticism"](https://isteve.blogspot.com/2007/09/g-factor-of-sports.html). (It would be really interesting if anyone's actually done this using the same methodology used to construct IQ tests!) But _athleticism_ is going to be an _very_ "coarse" construct for which [the tails come apart](https://www.lesswrong.com/posts/dC7mP5nSwvpL65Qu5/why-the-tails-come-apart): for example, world champion 100-meter sprinter Usain Bolt's best time in the _800_ meters is [reportedly only around 2:10](https://www.newyorker.com/sports/sporting-scene/how-fast-would-usain-bolt-run-the-mile) [or 2:07](https://archive.is/T988h)! (For comparison, _I_ ran a 2:08.3 in high school once!)
Anyway, so Murray and Herrnstein talk about this "intelligence" construct, and how it's heritable, and how it predicts income, school success, not being a criminal, _&c._, and how Society is becoming increasingly stratified by cognitive abilities, as school credentials become the ticket to the new upper class.
It's important not to overinterpret the _g_ factor as some unitary essence of intelligence rather than the length of a hyperellipsoid. It seems likely that [if you gave people a bunch of _physical_ tests, they would positively correlate with each other](https://www.talyarkoni.org/blog/2010/03/07/what-the-general-factor-of-intelligence-is-and-isnt-or-why-intuitive-unitarianism-is-a-lousy-guide-to-the-neurobiology-of-higher-cognitive-ability/), such that you could extract a ["general factor of athleticism"](https://isteve.blogspot.com/2007/09/g-factor-of-sports.html). (It would be really interesting if anyone's actually done this using the same methodology used to construct IQ tests!) But _athleticism_ is going to be an _very_ "coarse" construct for which [the tails come apart](https://www.lesswrong.com/posts/dC7mP5nSwvpL65Qu5/why-the-tails-come-apart): for example, world champion 100-meter sprinter Usain Bolt's best time in the _800_ meters is [reportedly only around 2:10](https://www.newyorker.com/sports/sporting-scene/how-fast-would-usain-bolt-run-the-mile) [or 2:07](https://archive.is/T988h)! (For comparison, _I_ ran a 2:08.3 in high school once!)
Anyway, so Murray and Herrnstein talk about this "intelligence" construct, and how it's heritable, and how it predicts income, school success, not being a criminal, _&c._, and how Society is becoming increasingly stratified by cognitive abilities, as school credentials become the ticket to the new upper class.