Polygamy and power structures. Polygamy allows rich men to corral all the women. If there are one million people in an area, and half are women, there will be 500,000 men. If each polygamist has four wives, 375,000 men will have no wives or children. If polygamists have an average of two wives, 250,000 men will be deprived of wives and children.
This is why polygamist religions begin with rapid expansion. Taking over new areas is the only way single men can find women. After they reach their natural area of expansion, polygamous societies tend to decline for an obvious reason. Their gene pools continually diminish in variety. Skills tend to move to the middle of the bell curve.
Over time, polygamous societies produce ever fewer Newtons and Edisons. The increased policing needed to control young men without families of their own imposes huge costs on the society, keeping investment capitol from forming.
There are historical indications of this. Throughout the last third of the first millenium, a polygamous empire made great advances in medicine, mathematics, and other sciences. By the last half of the second millenium, that same culture had reached a point of stagnancy. No intellectual advances were made in any area.
As polygamists prosper, they get more wives. That accelerates the intellectual decline. Reduced genetic variety, combined with the less motile sperm cells of older men, produces unaviodable results.
Young, single men in any society cause most of the crime and disruption. They are easily organized into military or para-military groups. Since they are kept from having permanent attachments of their own, they are easily encouraged to destroy other people who are “different” or who have more.
It is a fact that older rich men control every society. When wealth is measured by wives, and many men are wealthy in wives, revolution can only be avoided by getting young, single men to focus on destroying others.
Polygamy exalts selfishness. It is impossible to bring political stability to a polygamous society without mandating monogamy or sacrificing people within striking distance of angry, bitter young men who are given a few dollars worth of weapons and a lot of encouragement from older, selfish, wealthy men who value their own gratification more than the well-being of their own sons.
And daughters.
