Younger people used to be more emotionally mature than our young people are today, IMO. In the middle ages a boy was apprenticed at 7, became a man at 14 and was supporting himself (by hard labor usually) by 16. A girl by puberty had been taught to run a household. They got married, had babies, and died before age fifty (if the girl didn't die sooner in childbirth). In the industrial age young men weren't emotionally ready until possibly their early 20's to settle down. For women it was a bit earlier but they died younger than men so it worked out. Nowadays I don't think the average college student is mature enough to make a commitment like marriage. The divorce rate for teen marriages is many times the divorce rate for older people because most kids haven't learned that love is a decision, not a feeling. Some of them never learn.
So, my opinion is that if a person is mature enough for committment then younger childbearing is biologically ideal, but if the kid isn't grown up yet between the ears young marriage is a recipe for disaster. That being said, I met my husband when I was 16, began dating him at 18 and married him at 20. We're still together, so I guess we were mature enough to deal with it.
