1) I've attended delivery of mom of 12. This is nothing new.
2) We didn't evolve to have pregnancy at any specific age. When menarche begins, pregnancy can occur. However, success of prgnancy and of the mom living is lower at such a young age so I guess there is sone evolutionary pressure.
3) Age of puberty has gotten younger over the years. Many factors implicated. Those early games of "playing doctor" can have more serious implications.
4) it's not rape if there isn't a significant age difference between the two. At that age, girls are often more physically and emotionally mature than their male peers.
That having been said, overall a sad state of affairs. One wonders it this could have been prevented. I wonder what information about sex this girl was given (or not) by parent(s) prior.