Home > Ape Mind, Critical Thinking, Dystopia, Philosophy sans Sophistry, Reason, Secular Religions, Skepticism > Arithmetic, Conditions, Constraints and the 40-80 Ratio

Arithmetic, Conditions, Constraints and the 40-80 Ratio

Before I attack the actual paper about the 40-80 ratio, let me attack a few more common sense assumptions about the reasons behind popular belief in that ratio.

The first question is:

What was the average number of live children born per fertile woman?

This one is easy.. Women have traditionally got pregnant from their mid-teens to mid-40s, we can assume a fertile period of about 30 years- under ideal conditions. The length of breastfeeding for most societies and individuals throughout history has been between 1-2 years. Since women cannot get pregnant while breastfeeding (at least earlier on), and the duration of human gestation is about 9 months- we can assume that each fertile woman had one kid every 2.5-3 years.

About 20-40% of all pregnancies (embryo implantations) end in miscarriage- often within the first two months. Plus some pregnancies caused complications impairing further fertility or resulted in the mother’s death. We can therefore assume an average of about 10 live births per fertile woman, through most of human history.

Which brings us the second question..

What percentage of live births reached adulthood?

Most evidence indicates that just under half of all live births lived to adulthood, through most of human history. Let us be optimistic and say 60% of live birth reached adulthood and all were fertile young adults.

The human sex ration is 1:1 for males and females, and therefore we can assume that each fertile woman under fairly optimum conditions had 3 boys and 3 girls who reached adulthood. Since 1 boy and 1 girl are the bare minimum required for maintaining population, this allows a margin of 2 boys and 2 girls. Once you factor in wars, diseases, injuries, infertility and premature death of kids- we have a real margin for expansion of less than 2 males + 2 females per woman.

Do you see the problem? Let me explain..

Pre-modern medicine and hygiene, the number of fertile adult descendants per woman was low enough to cause serious problems if many of them were killed by war, disease or slavery.

Many ‘experts’ on human behavior and evolution never consider that the combination of such a perilous existence and small group size (200-1,000 per group or upto 10,000 per meta-group) on behavior. These conditions likely created a strong desire to reduce mortality from things like hunting and conflicts. In any case, such mortality was most likely to affect men- who were important in both hunter-gatherer and agricultural societies.

The secondary problem is that men who did not get pussy would not work or cooperate, so any attempt to significantly reduce male access to women would likely result in the dissolution and destruction of that group.

Nobody is denying that some men must have got laid more than others, but the idea that most men did not have enough access to pussy simply does work in any pre-industrial society.

One has to also factor in the type of law enforcement and social mores in such groups. Throughout most of human history, practices such as beating your “wife”, restraining her to have sex, public chastisement of misbehaving “wives” were widely accepted for a reason.

A pissed off guy who did not play nice with the group or work hard was much bigger threat to their survival than a screaming woman who complained of rough sex, choice of guy or getting a good beating.

There is a reason most long-lasting cultures are both patriarchal and prefer male children over female children.

Men do the work, as long as they can expect to get laid.

Another way to put it is:

Continuation of civilization requires that most men can frequently stick IT into a woman, who will play along. Without that incentive, even hunter-gatherer groups tend to disintegrate rather quickly.


  1. namae nanka
    August 3, 2010 at 3:39 pm

    Is there a reason proposed for why most people use “ration” when what they want to say is ratio?

    You have any ideas?

  1. August 8, 2010 at 2:14 am

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