[klenwell]

According to the professor on whose research this information is based, a third of the world's languages have this linguistic peculiarity.

You can hear her account around 30 minute mark of this RadioLab episode: http://www.radiolab.org/2011/jan/25/birds-eye-view/

[jkn]

Can't listen to it right now, but this article:

http://online.wsj.com/article/SB1000142405274870346730457538...

suggests that speakers of all these languages share the good spatial orientation abilities. Anyway it's true then that my argument doesn't hold. One should first verify if there is a subset of nomadic peoples that lack this language feature, and that they have poorer orientation abilities.