Why is the long-term mating strategy common in humans

The end goal of sexual reproduction is to successfully pass on one’s genes to the next generation. In order to motivate us to achieve this goal, we’re hard-wired to find certain members of the opposite sex attractive and form relationships with them.
  
A typical relationship can be defined as a long-term or an expected long-term bond between individuals each of whom will ultimately contribute half of their genetic code to produce an offspring and raise it.

The long-term mating strategy (monogamy), as opposed to the short-term mating strategy, is the most preferred mating strategy worldwide. Since marriage is found in all the cultures, even in those that have been cut off from the rest of the world, it cannot be a social construct.

The desire to seek a long-term partner and produce and raise offspring with them is hard-wired into the human psyche by the engine of natural selection. But why?



The evolution of monogamy

Our early ancestors probably engaged in unconditional short-term mating. They basically banged whenever they could. They had to. Survival was extremely hard thanks to predators and diseases. Only by reproducing indiscriminately and as often as possible could they increase the chances of successfully passing on their genes.

But about 2 million years ago, something changed. Our early ancestors became bipedal i.e. they stood up and walked. The female pelvis grew narrower but the human brain grew significantly in size as we freed our hands, made tools, started fires and developed language.

So for a baby’s big head to pass through the narrow birth canal, the baby had to be born well before the brain could be fully developed. This evolutionary trade-off resulted in a highly vulnerable and helpless baby with prolonged childhood, wholly reliant on its parents.

It was probably at this stage in our evolutionary history that monogamy became the dominant mating strategy in order to facilitate adequate support, protection, and care that a helpless baby requires from both its parents.

baby grasping finger
Our ancestors were always on the move so newborn infants had to grasp their caregiver’s bodies tightly to avoid falling off. A baby’s grasp can be strong enough to support its own weight! 

Women pursuing monogamy

Women pursuing monogamy makes all the sense in the world. Since they can produce a limited number of offspring with many time constraints and huge costs, they can best ensure their reproductive success by raising their few offspring well.

Although they can benefit from short-term mating, the costs are pretty huge.

Men pursuing monogamy

Men pursuing monogamy is an interesting phenomenon because they have a lot to gain from short-term mating and very little to lose (see what men gain (and lose) by pursuing the short-term mating strategy).

But the fact that so many men pursue long-term mating tells us that the benefits of monogamy are somehow outweighing the benefits of short-term mating in many contexts.

Men are wired to pursue short-term mating so that they can father as many children as they can. This equation of reproductive success for men changes when you factor in vulnerable babies with big heads and prolonged childhoods.

It’s no longer about quantity but about quality of offspring. Only by providing adequate care to his offspring can a man ensure that it will survive and successfully reproduce later in life.

There’s little reproductive success to be found in fathering dozens of offspring who all die or fail to reproduce because they didn’t receive adequate care.


Pulling off the anchor

There are psychological programs for short-term mating and long-term mating strategies in both men and women. What strategy they choose will depend a lot on the cost/benefit calculations they carry out in their heads and the context in which they make the decision.

Men are pulled more strongly toward the short-term mating strategy because they can benefit from it reproductively. What anchors them to long-term mating is the need for a great amount of parental investment and care that a human baby requires.

What do you think would happen if we pulled off that anchor? What if parental investment and support of a baby are taken care of by something else, like government funds and childcare policies or even well-to-do mothers?

In such a situation men are likely to revert to pursuing short-term mating or serial monogamy because they know that each offspring that they father will be well taken care of. Now, in order to maximize their reproductive success, quantity again becomes important.

In the developed countries with good childcare support divorce rates are high mainly because men start new families every now and then. This has resulted in the rise of single moms.

In the developing countries that are poor and barely supporting their own economy, let alone supporting children, ‘single mom’ is an alien concept or a highly stigmatized one. Single dads do exist but they’re far less common worldwide because that kind of a strategy is not very reproductively beneficial for men.

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