I’d been meaning to post something on this for awhile, forgot, then was recently reminded again.  This has to be a top candidate in the category of arbitrary and useless skills that people get ridiculously good at:

Link if embed doesn’t work: http://www.youtube.com/watch?v=LyU5v0ZYMjI

The point is not to make fun of this kind of skill acquisition but to raise the question of why we do this.  In particular, the first people who started racing through stacking cups had to have been doing it because it provided some intrinsic reward for them for motivation.  I think skill learning does have some intrinsic reward (and maybe more for some people than others), possibly related to the involvement of cortico-striatal loops that use or are at least near reward processing (and the common dependence on dopamine).