Scientifically speaking, sex has two main purposes: procreation and the bonding of parents for the care of children. If people do not reproduce in their lifetimes, it is a truism that upon their death there will be no more people. If once a child is born, the child’s parents or another caregiver do not care for the child, however imperfectly, the child’s chances of reaching an age to reproduce is virtually zero.
Certainly, people have engaged in sexual activity throughout time, whether voluntarily or involuntarily, for purposes other than procreation or bonding with a mate; for pleasure, to be entertained or to entertain, for money or barter, to dominate the other or ingratiate oneself to the other, as an act of aggression or a token of submission, for any number of reasons or combination of reasons. And even when a man and a woman engage in sexual activity for the expressed purpose of procreating, only a small percentage of those sex acts are successful in producing offspring. Procreation, even when hoped for, is far from guaranteed.
In times before the availability of modern contraception, in the few decades after World War II, not everyone paired off in couples, and certainly not everyone reproduced. Historically, women died in childbirth and men died in war. Both died from accidents and diseases at rates unheard of today. Even absent death and disease, giving birth to and raising children was not necessarily the norm.
As an example from my own family, one of my great-grandmothers, Amazetta “Zetta” Curtis, had at least 4 and maybe 5 children. Her first child, Goldie, was born out of wedlock in 1887 in upstate New York. Zetta subsequently moved to Chicago and married my great-grandfather, Mark Ichabod Warren. Zetta had three and perhaps four children while married to Mark; my grandmother Winifred in 1893, Raymond in 1896, and Norman in 1899. Some of Zetta’s letters hint that Raymond had a twin sibling that died in infancy. Of Zetta’s four children that survived infancy, only Winifred had any descendants. Golda married but never had any children, Raymond married and had one child that died during World War II without having any children, and Norman never married or had any children. Winifred married Russel Boeman and had three daughters and two sons.
Russel’s paternal grandparents are another example. George W. Boeman and his wife Sarah Martin had three children, one of which died in infancy. Their only daughter, Orlie, married and had one daughter who never married or had any children. Their only son, Sigler, had three sons, Harry, Roy, and Russel. Harry never married and never had any children, Roy married and had one daughter who never married or had any children, and Russel married Winifred and had five children as mentioned before.
The point is that anyone who studies in depth family history, at least in the United States and particularly through records like censuses that detail family relationships, will notice that men and women not getting married and not having children was not unheard of prior to the advent of contraception. Stigma or no stigma, it was not uncommon at all. There is no way to know for sure why these men and woman never married, or if married never had any children. Certainly, a percentage of these individuals were attracted to the same sex or in same sex romantic relationships. Others undoubtedly wanted to have children but, like some couples today, where unable. Others likely simply chose not to have children or never found a partner to marry or have children with. A sizable percentage of people remained childless in decades past despite the overall natural increases in the population.
Today, though, such a large percentage of people of child-bearing age are not having children that not only is the population not increasing, but declining in many places throughout the developed and developing world.
Population scientists estimate that in order for a population to remain relatively stable, on average each woman throughout her lifetime must have 2.1 children. Anything below a fertility rate of 2.1 and the population declines, anything above and the population increases. In the United States, the current rate is estimated to be 1.84. Two of the United States’ largest competitors on the world stage, China and Russia, have even a lower fertility rate, both at 1.60. Two of the other largest economies in the world, Germany and Japan, are still lower at 1.48 and 1.38 respectively. Outside Asia, Europe, and the United States, the ninth largest economy, Brazil, is also appreciably below replacement at 1.73. Of the ten largest economies, only India at 2.28, with the fifth largest economy and second largest population, is above replacement. But even India is projected to fall below the replacement rate of 2.1 this decade. The world’s largest predominantly Muslim country, Indonesia, and perhaps most influential, Saudi Arabia, are also below replacement at 2.04 and 1.94 respectively.
The simple fact is that if sexual activity does not entail procreation in the behaviors of a critical mass of people, populations will inevitably decline. As a world wide trend, decoupling sex from procreation has and will continue to have profound consequences for all of humanity, akin in times past to the invention of the machine gun, or atomic bomb. Once the decline begins it will very difficult, and painful, to reverse.