ABC:

A Phoenix, Ariz., woman put her 5-week-old baby on top of her car in his car seat and drove away, apparently forgetting he was there, not even noticing when the seat fell off the car and landed in an intersection, police said.
Neighbors discovered the baby on the roadway, still strapped to his safety seat, which was lying on its side. Luckily, the baby was unhurt.
The baby’s mother, 19-year-old Catalina Clouser, who allegedly had been smoking marijuana, was arrested and charged with aggravated driving under the influence and child abuse, police said.
Do not blame marijuana. Blame instead the weakness of sex eduction. Two things pointed out by the sociobiologist Sarah Hardy: One, young mothers are usually not the best mothers (this is true also for chimps and other primates). An infant who has a teen or child mother has entered life through a bad door. Death and abandonment are closer to its life than the life of a child raised by a mother who is older and prepared. Two: In the old and dark days, the chances of a child or teen becoming a mother were not as great as they are today not because of changes in morality but major changes in nutrition.
Looked at comparatively, rates of teenage pregnancy (which happen to be higher in the United States than in any other developed nation) have less to do with moral decline than with changes in the nutritional status of human beings over the last tens of thousands and hundreds of years. Teenage pregnancy, then, is very much a human-made problem, a human-solvable public health issue, not a moral one.

As in all apes, human ovaries evolved to factor how much fat a woman’s body had stored. For a still partially dependent girl living among nomadic hunter-gatherers, this indicator of nutritional status would have been synonymous with how much social support she had. Among nomadic foragers, where youngsters depend on shared nutritional subsidies from other group members, a young girl’s fat reserves provided a fairly good indicator of how much social support she could expect from parents, grandparents, boyfriends, her mate perhaps, as well as other group members.

By and large, the plumper a girl is, the sooner she matures. Girls growing up in nomadic foraging society on the African savanna remained active, intermittently fed, and very lean, menstruating for the first time closer to sixteen than twelve, the average age of girls today in sedentary, hypernourished Western societies.

We are humans. Humans are the cultural animal. We use culture to solve adaptive lags and physical defects. In the way we use glass to correct flaws in vision, we need contraceptives to solve this unexpected shift in human sexual development. That mother should be happily smoking pot and not sadly raising a child.