From what I've seen throughout middle school, high school, and university, guys procrastinate more.

It's also widely known that women mature faster than males, and according to the sidebar, males keep maturing until their late 20s.

My questions:

Do you think this differential in seriousness is due to a lack of development in males pre-20s? Does anyone here have any evidence (anecdotal or otherwise) for this being the case?

Feel free to post any studies/non-anecdotal evidence for the maturation differential between the sexes.