One of the hallmark distinctions between us and other animals is the length of time we spend raising our young. Young calves are capable of standing on their feet right out of the womb, whereas human babies would die without immediate and prolonged caretaking. The transition from zero weaning to adolescent care-taking must have included an intermediate stage that would be familiar to the grating experience of witnessing someone over-parent today. Watching someone who is hovering over the sandbox, monitoring their child's every move with a hawk-like vigilance, probably has analogs to hundreds of thousands of years ago.

When different subspecies of Homo Sapiens were intermingling, there must have been a mother who held and played with her seven-year-old son, speaking kiddie talk until the wee hours, to the derision of others. Someone from another tribe might have scolded her, "By that age, our children are hunting, fighting and even having sex. Kids need to be kids!" But then this "helicopter" mom kept it up, and all this stimulation during the child's formative years helped cultivate imagination and creativity. All the time he spent playing in the sandbox when he was young later gave him the bright idea of storing grains in a dry place or for burying raw meat in ice, and his tribe then stayed healthy during a rough winter or maybe an Ice Age, whereas the other ones died off. His knowledge became valued, and so he reproduced often, and then he had many daughters who had the same "over"-parenting gene his mom had. They continued to care for their children as long, if not longer, until we wind up in the situation we are in today, with those resisting over-parenting, and those soldiering on because they can't help it.

The paradox of declining birth-rates in Europe and the developed world is a puzzling anomaly. The birth-rate increases with lower incomes, which is counter-intuitive since more wealth seems to imply a greater capacity to support a family.

However, the higher birth-rate in low-income and low-education levels may simply be due to limited access to contraception. Or it could be due to the reproductive urgency of a harsh life; when people close to you die young, it increases the urgency to couple and reproduce.

Either way, education and money obviate those things, so then what's left? Perhaps the declining birth-rate could be explained by the simple folk short-hand excuse, "The world doesn't need more people."

Perhaps, when money and a certain station in life bring about the luxury of rational choices and family planning, to take on the costly proposition of child-rearing, the motivation has to come from external forces. Somehow, the couple needs to believe, "We need more people."

"We" could be anything. The default "we" is usually your city, church or culture. If for example, you are attached to Zoroastrianism (one of the oldest surviving religions, which now only has less than 200,000 members), and you attend the meetings regularly, you might feel the exhortation from elders to be fruitful and multiply as the only way to keep the culture alive. You may then pair up with a fellow Zoroastrian and shoot for five or more children.

In the absence of religion, you might feel like your town needs more people. If you were one of the early pilgrims, for example, reproduction would be an urgent communal necessity to grow the city to a large enough size to survive the ebb and flow of seasons and foreign threats.

But most Americans live in big cities now, and if you are ever stuck in traffic, it's easy to think that your city doesn't need more people. "We do not need more people, in fact, it would be nice if people went away."

This could all be a psychological trick, though, because your mayor wants more growth, and population growth is crucial for GDP growth. However, the individual is not attached to that at all. The individual's experience is that of overcrowding. If living spaces are tight, it might be easy to think, "Well, where would I put a new baby? How would I cram a kid into an already overcrowded school? How will my kid find a job one day?"