The mechanism of cultural evolution being described here deserves some digression. 

The fact is that humans often do behave in ways that seem irrational by purely Bayesian standards. We fly in the face of what reason says would be our best probability policy. 

Even in our time, some adults still spank kids. Some men still bully women. Some states still execute their worst criminals. Research based on observation and analysis of these patterns of behavior suggests strongly that they don’t work; these behaviors do not achieve the results that they aim for. In fact, they reduce the chances that we will achieve those results. These behaviors and the beliefs underlying them are counterproductive. Therefore, we must ask: Why do we, as rational humans who usually operate under a rational, Bayesian system sometimes hold on so obstinately, in a few areas of our lives, to beliefs that cause us to act in irrational ways?

                                           

   

                  Lethal injection room, used to execute criminals (credit: Wikimedia Commons) 

The reply is that we do so because our culture’s most profound programming institutions—the family, the schools, and the media—continue to indoctrinate us with these values so deeply that once we are adults, we refuse to examine them. Instead, our programming causes us to bristle, then defend our “good old ways”, violently if need be. If the ensuing lessons are harsh enough and there is a reasonable amount of available time, a whole society can sometimes learn, change its ways, and then adapt. But the deep social change is always difficult. Alfred Whitehead, in his 1927 essay Symbolism: Its Meaning and Effect, wrote:

“It is the first step in sociological wisdom to recognize that the major advances in civilization are processes which all but wreck the societies in which they occur.”⁴

                                                                    

                                            

                     Alfred North Whitehead (credit: Internet Encyclopedia of Philosophy) 

It is also worthwhile to say the obvious here, however politically incorrect it may be: all our obsolete but obstinate beliefs, moral values, morés, and behavior patterns did serve useful ends at one time. 

For example, in some but not all early societies, women were taught to be submissive, first to their fathers and brothers, then to their husbands. The majority of men in such societies were far more likely to help to nurture the children of their socially sanctioned marriages because they were confident the children born to these submissive women were biologically their (the men's) own.

Raising kids is hard work. In early societies, if both parents were committed to the task, the odds were better that those children would grow up, marry, have kids of their own, and then program into those kids the values and roles that the parents themselves had been raised to believe in. Other non-patriarchal societies taught other roles for men and women and other designs for the family, but they weren’t as prolific over the long haul. Patriarchy isn’t fair. But it makes more babies who become adult citizens.

Traditional beliefs about male and female roles didn’t work to make people happy. But they did give some tribes numbers and thus power. More workers and soldiers. They are obsolete today, partly because child nurturing has been largely taken over by the state (public schools), partly because no society in a post-industrial, knowledge-driven economy can afford to stifle half of its human resources (i.e. the female half), and partly because there are too many humans polluting this planet now. 

Population growth is no longer a keenly sought goal because it no longer brings a nation power. Millions of poor today are more likely to be a liability than an asset for a nation. If they suffer too much, they might even start a violent revolution and unravel their own way of life.