There was an article in New Scientist some months back (sorry, haven't kept it so can't give the reference) that did a good job of explaining why single teenage motherhood is actually a good strategy under some circumstances - like no job, no prospects, and less than average life expectancy. It makes sense if you consider that, biologically at least, our sole purpose in life is the propagation of our genes.

Some people OTOH may consider that NS has a lot in common with DM...