In Genesis, the first humans are instructed to be fruitful and multiply. Given that the human population now exceeds seven billion individuals, one could assume humans took that instruction to heart. Along the way, the transition from hunter gathers, where the population was constantly on the move, to an agrarian society where everyone stays put, no doubt helped humans in this goal. Development of technology and industry, advances in medicine, and improvements in our diet also played a part, and for that, we have our advanced brains to thank. Had our ancestors not begun to walk upright, which freed their hands to allow for tool making, which, in turn led to the the development of our brains, we might still be swinging in trees, rather than building skyscrapers, unraveling our genetic code, and planning a trip to Mars. Humans have done such a good job of distancing ourselves from our primate past that we’ve created numerous myths of divine origin to explain where we came from rather than accepting what the evolutionary evidence tells us.
In the film The Adventures of Baron Munchausen, Robin Williams plays a king who can detach his head from his body. Connected, he’s course and vile, and enslaved by his animal instincts, but detached, he’s thoughtful and contemplative and fully intellectual. Many people like to believe humans operate as essentially rational creatures, guided by common sense, and ignore the many, many times humans behave in ways contrary to rational behavior. Nowhere is this more evident than in the area of attraction and the dating rituals humans devise for finding and choosing a mate. People spend much time and many words trying to explain why they are attracted to certain people and not to others, or why a particular relationship didn’t work out, attempting to conceptualize the instinctive biological imperitive to survive and procreate. Applying too much rationality to reproductive behavior can have other implications relevant to the continuation of the species.
One of the consequences to increasing intelligence is that humans can become focused on other creative endeavors and begin to override the biological imperative by either delaying or simply refusing to reproduce for a variety of reasons. The religious sect known as the Shakers was an example of a community who practiced celibacy, even between married couples, and chose to grow by recruiting new members rather than via the traditional route of having children. They found alternate means, such as weird dances and building distinctive furniture, as a way of channeling their creative impulses away from their sexual desires and, as a result, all that remains of their community, aside from a few later converts who may still practice the lifestyle, is the furniture they created. The sect, by and large, went extinct when the last of its stalwarts died off during the twentieth century.
Typically, the higher up the economic ladder one moves, the fewer children one has. In an agrarian society where many individuals are needed to perform the necessary work, larger family sizes are advantageous to effectively create the workforce a family would require. In my genealogical work, I’ve seen families with as many as eighteen to twenty children, though not all by the same mother. For those living in cramped urban settings, large families are less of an advantage, though they can be found there as well. Equally so, given the risks inherent in childbearing, expecting a single woman to bear numerous children over a relatively short period of time can be dangerous for both the woman and her offspring. There’s a reason why the mortality rate for women and infants was so high in colonial times besides the lack of adequate pre- and postnatal care available.
While a change in thinking can alter the desire to have children, we have yet to overcome a simple fact of reproduction. In order for there to be a child, there has to be a contribution from a man and a woman regardless of whether the two have sex. Neither gender can produce a child solely on its own. There has been talk of fusing genes or chromosomes, or otherwise cloning a person to overcome this situation, but as of now, science has yet to produce a human child using this method. The fundamentalist claim that homosexuals can’t reproduce doesn’t take into account the fact that both parents no longer need to be present at the moment if conception. Perhaps this is another reason the far right hates science so much.