According to the conventional wisdom of anthropologists, the ancestors of humans lived in Africa. Early ancestors were forest dwellers. This is the origin of our gripping hand, which allows us to spread the thumb and oppose it to the other four fingers. Experts speak of the thumb's ability to abduct and oppose. The habitat of our ancestors then changed, possibly due to a change in climate, to a savannah. Our ancestors began to walk more upright. The hands were no longer needed for locomotion and were available for tool use.
However, the ability to use tools could not have been the driving force behind the increasing intelligence of our ancestors - at least not alone. For hundreds of thousands of years, our ancestors made do with simple tools made of stone, wood, and bone. The driving force behind the development of intelligence must have been elsewhere. There must have been a very strong selection pressure that lasted for generations. Since humans have few natural enemies and the climatic conditions did not exert extreme selection pressure, the selection pressure could only have come from within - from living together within our own species. Our ancestors almost certainly lived in small social groups, just like our great ape relatives. Unfortunately, there is no evidence of how our ancestors lived together socially; we can only hypothesize and see if there is a selection pressure that can explain the characteristics of modern humans.
One hypothesis is that human ancestors were violent and cannibalistic. This may sound horrible, but it is plausible because our close relative among the great apes, the chimpanzee, also occasionally exhibits cannibalistic behavior, hunting down chimpanzees from other groups, which are then brutally treated and eaten. To survive and thrive as an individual in a cannibalistic species, one must be either physically strong or mentally alert. Those who are physically strong are better able to fend off attacks or not be attacked in the first place out of respect and can act aggressively towards others themselves. If you are smart, you can read your opponent's intentions and be more successful in the end, even if you are physically inferior. Of course, it is best to be strong and clever. The stronger and smarter the attackers became over the generations, the stronger and smarter the other members of the species had to become, otherwise they would be eaten and thus no longer participate in biological reproduction. Cannibalism therefore creates a self-reinforcing selection pressure within a species, in which only the strong and/or clever survive. This would explain why Homo sapiens has become so much more intelligent than its ancestors and closely related species.
Modern humans are still prone to violence, but they are much more peaceful than chimpanzees. Therefore, there must have been another crucial selection pressure. This selection pressure could have come from the behavior of female group members when choosing a mate. Biologists have noticed that both humans and domesticated animals have strange similarities, such as a shortened facial skull and diminishing body hair compared to earlier wild forms. Consider the appearance of domesticated pigs compared to wild boars. Evolutionary experiments with various mammalian species have shown that these secondary characteristics develop when the most peaceful animals are favored in breeding selection. Applied to humans, this would mean that our female ancestors had a preference for peaceful male mates.
At first glance, this appears to be a logical contradiction: the (male) leaders of a group should be as strong and aggressive as possible in order to defend the group against external (or internal) attackers or to actively go on the prowl against other rival groups. On the other hand, their aggression and cannibalistic desires should not be directed against their own group members, especially the physically weaker female group members and offspring. When choosing a mate, female group members had to make sure that there were enough aggressive male offspring whose aggression would not affect the group members later on, and on the other hand, that a few smart ones who did not make it to the top of the group due to lack of physical strength were also given a chance to mate. Such a balancing act can only be achieved through ambivalent mating behavior - including cheating and cuckoo babies.
This can only be achieved through complex social behaviors that are not fully transparent to male group members. And as the time between birth and sexual maturity became longer and longer for our ancestors, the male leaders also had to be discouraged from practicing infanticide, i.e. the widespread custom in many animal species of killing the young children of their predecessor when the leader changes. If our ancestors had consistently practiced infanticide, they would probably have died out because hardly any children would have made it to adulthood.
If these two hypotheses on essential evolutionary selection pressures in human development are correct, then the consequences are as follows:
- To begin with, tendencies towards infanticide provide a selection pressure towards being smart, as clever offspringones might have found ways to prevent from being killed at least once they had achieved a certain minimum age.
- Dumb females had a selective disadvantage that they could not compensate for with physical strength, since males were almost always stronger, and they had to be clever to avoid having their children killed in the event of a change of leadership in the group. Females therefore had to be at least averagely intelligent if they did not want to be "mated out" on a statistical average over many generations. However, females with above-average intelligence may also have been at a selective disadvantage because the boss may not have tolerated being dominated by a partner who was too smart in the long run.
This consequence coincides with an observation that can be made in schools today. Most girls perform slightly above average - very weak performances, but also singular individual talents, are comparatively rare. This observation may also have cultural causes, because girls tend to cope better with the school system in terms of their social behavior, but the observation at least does not contradict the consequences derived from evolutionary biology.
- In males, on the other hand, both the strategy of being strong and the strategy of being particularly clever could lead to a selective advantage. Cleverness and strength should therefore have a wider range in males than in females.
This consequence is also consistent with observations of modern humans: The range of physical strength and intensity of talent is much greater in boys than in girls. This phenomenological finding is also consistent with a molecular biological finding: while female individuals have two X chromosomes, ensuring a certain balance between the traits inherited from father and mother, male individuals have only one X chromosome, meaning that changes in the genetic material have a greater effect here. The greater variation in males is not due to the Y chromosome, which is much smaller than the X chromosome and has been progressively shortened throughout evolution, but to the lack of a second X chromosome.
- The social behavior of females must be much more complex than the social behavior of males. The real power had to lie with the female leader of the group, but she had to use her male partner to exercise her power, and the male partner was not allowed to realize that he was really just a tool in the hands of his partner. Well, this constellation can probably still be found in many couples and families today, where the man is formally the head of the family on the outside, but the woman "wears the pants" at home. Men often believe that they are the bosses, but in reality they are just the smoking gun in their partner's hand. This stereotypical gender relationship is wonderfully portrayed in the animated series about the clever Viking boy Wickie, whose father Alvar is the strong leader of his Viking village, but has nothing to laugh about at home with his wife Ylva.
So our intelligence did not evolve primarily to use tools and conquer the earth, but to manage our social life. To do this, human social behavior must encompass a wide range of evolutionarily induced behavioral patterns. Human freedom consists in choosing among different patterns of behavior that are best for us depending on the situation. The increase in freedom over the course of human evolution can again be explained by a positive feedback loop: Those of our ancestors who were able to variably choose between different courses of action were less predictable for their opponents in attack or defense, and thus could gain a survival advantage by correctly predicting the future. This ability to freely weigh up courses of action gradually became established throughout the tribe, which in turn made the opponents more and more clever, and an advantage could only be gained by an even greater degree of independence from predetermined reflexes and by an even more precise weighing up of different future scenarios. As humans, we have thus trained ourselves to be free. Or damned, as the case may be.
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