This is what morality looks like in terms of biology.
Summary: Sociobiology is the science of how our genes drive our behaviors, especially our reproductive behaviors. It describes that the different reproductive potential of males and females leads to very different behaviors. Males can potentially have far more children than females, so their strategy includes risk-taking and a fighting to have access to multiple females. The females are far more limited in how many children they can potentially have and so taking risks is unlikely to be of benefit to them. Instead, their strategy is to get the male with the best genes possible. Theirs is more of a quality strategy as opposed to the male's quantity strategy. This is a typical mammalian strategy, but it gets more complicated the more developed the society is such as in wolves, primates, elephants, porpoises, etc. In humans, the long demanding development period of children has led to a more and more monogamous situation. That has reduced the advantage for males of risk-taking and fighting for mates. At the same time, more and more the female is trying to get investment by the male in helping with the development of the children. This, in turn, has allowed and propelled the society and civilization to develop more, which has also then extended the child developmental period even more. Ultimately, though we are still quite genetically adapted to the tribal strategies, things have changed and more importantly, we have changed, we have developed and chosen to use different strategies than the ones our genes may tell us. Our moral instincts can adapt to changing circumstances by using new moral systems. We can adapt strategically to a new ecology before the ecology really exists or our genes are adapted to it.
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Sociobiology is a science that was popular in the 70's and then lost favor. I hear that it is popular again. I don't much care. It is quite logical and that never changes. Its premise is that our behaviors are driven by survival strategies and instincts. It's about evolution, genes, instincts, competition, and survival. At the end of it though, we are clearly shown that human survival is about more than genes and instincts. It is about our choices as individuals and as a species about our future and deciding what we will be. It's about learning and deciding our strategy.
The largest difference between males and females is the number of potential offspring. The second largest difference is how much investment they have in their offspring at any time. Related to that is who can get stuck with the offspring at any time. How these factors play out to make the basic strategies of reproduction which is much of the strategy of survival.
The basic rules of Sociobiology apply to species that have any social behavior. That includes fishes, reptiles, birds, and mammals because though their social behavior would often be considered very limited, they must cooperate to reproduce. The most important aspect of it though is competing for reproductive resources. Because males normally have the potential for far more offspring than females, the strategies are different. (To keep this short and on point, this discussion now refers only to mammals with internal fertilization, though the same rules apply to other species as well.) So females may try to get reproductive resources that can include nesting material, food, protection, etc. Nothing they can do can greatly change their reproductive potential. Males, on the other hand, tend to have more of a quantity than quality strategy. Their reproductive success can be enhanced by mating with multiple females. This is seen in the common "alpha" strategy of mammal males competing for "harems" of females. He can potentially have a huge number of offspring if he can control a group of females and keep other males away. Males are evolved to take more risks including fighting for reproduction. It is why they are usually bigger than females. The most important resources for females though, more than even physical resources, is superior genes. Females promote the competition between the males so that they can know which is the superior one to reproduce with. They use beauty to attract him. Even when they "demand" physical resources before mating that will help the survival of their offspring, they are selecting for the fittest male.
That is the most basic description of Sociobiology as it applies to mammals. We're working our way up in complexity though. There are all kinds of complexity that can be added. "Social" animals like whales, wolves, elephants, primates, and others have unusual or unique circumstances that can change or modify that basic mammalian pattern. One case is that while generally after mating, females raise the young alone, different forms of monogamy can occur when conditions are harsh or otherwise require it. Otherwise, males of the same species are dangerous to a female with young. They use the same resources and may well kill her offspring. Generally, females of a specie don't want males f the same specie around, except in exceptional cases. (Note that female strategy may include killing the offspring of other females or preventing them from even having offspring.)
Notice, and this is critically important to human behavior - in some species females are adapted to accepting monogamy when needed. To be monogamous and help the females raise the young, males have to adapt more. That may include bonding behavior to the female. The female though may not be exhibiting bonding behavior. In humans, sometimes they do, sometimes they don't. This will be an important issue in the future.
As a general principle, almost no behavior is unique to male or female humans. Training of children may include emphasis of the more gender appropriate behaviors. This refers to children with normal heterosexual instincts and does not refer to individuals with sexual instincts that do not match their physical gender. Biology is not perfect and sexuality can potentially be ambiguous at the best of times. Ultimately, as is the case in so many situations, it may simply come down to a decision to survive. not how.
Another modification on the basic mammal reproductive behavior that those social species have is family and even clan social behavior. Then the male competition may be very restricted and competition for the best genes involves both sexes in a strategy called Status. Anthropologists define status as who an individual has reproductive access to. The tribe bunny hunter does not get to make time with the Buffalo Chief's daughter. It also allows competition between families. Frankly, status can take on completely unexpected forms from the great hunter to who wears a suit best or has a big wad of money. Status drives... well in ways, it can drive most of human behavior... Which makes sense in terms of evolution no matter how weird it can look objectively. (...And also can make this topic of status ridiculously difficult to describe. Because of other factors about the genes, needing to deal with that complexity involving status, largely goes away, even if the instincts and importance do not.) The obvious question about status is how much can an individual judge about the genes of another individual. The answer would probably be not much except for the fact that we are highly evolved to do just that. We have all kinds of instincts to analyze the genetic nature of other individuals. Apparently, we have mechanisms to detect even antibody comparability.
Power is the power to kill (Roman commentary). No matter how developed social behavior becomes and what forms it creates to reduce aggressive competition, aggressiveness doesn't go away. It is as real as feminine beauty. There are so many ways aggressive behavior can be used in so many forms of competition. ("Aggressive" is synonymous with "Active" perhaps more even than with "violence".) VIolence in society may or may not be well controlled by law. If it is not, deterrence is the only effective response. Anyone using an aggressive strategy must also calculate the potential cost. Violence is always a risky strategy.
In tribal humans, aggressiveness, including violence, was an excellent strategy. By the way, in ways this discussion is entering the zone of speculation, but the more data the anthropologists find, the more they see aggression. Consider that the past leads to the present and often the future. The needs of civilization are working against that though and examining history, there were many societies and groups that were either disinclined towards violence or possibly just really bad at it.
Through time, human males have used various strategies for "reproductively" acquiring females. One of the best-known examples we have data on is that about 14% of modern Mongols are descended from Genghis Khan. Male polygyny is natural in most mammalian species. How common was it in humans? Perhaps more interestingly, why is it not as common now? There is evidence that 12,000 years ago, when tribes were really large organizations, there was warfare that was for acquiring females. It led to the death of a major percentage of men to the point that it put human genetic diversity at risk. Pitcairn Island offers an interesting lesson in the strategy. Feudalism of various forms was basically the social and political structure of the world following the time of the tribes. The ruling class males would have had a huge reproductive advantage generation after generation. Even later with the rise of the city-states and industry, the power of economics, wealth, gave as much potential for status as the ruling class had. There would have been a constant flow of genes from the upper classes to the lower classes. There would have been a continual replacement. (I might argue that as cantankerous as many Americans were, they were commonly the un-inheriting offspring of the nobility.) The point of this though is that polygyny as is meant by sociobiology, a reproductive strategy has been common through all of history. Has that changed and if so, why?
(I would go so far as to speculate that humans before some important development, perhaps language, were in a more precarious position in the ecology where survival depended more on cooperation and violence within the tribe was more of a risk to the tribe. After the development of language or something else, humans dominated their ecology enough that it was other humans that were the main danger to individuals rather than external factors from the ecology. It was then that a strategy of violence became more useful compared to maximum cooperation previously needed.) Back to it...
Marriage is a custom that formalizes mating, but while there have been marriages for a long time, it rarely stopped polygyny. Marriage became necessary when there was property involved. It was a custom of the wealthy. Primogeniture, inheritance of property and title by the firstborn son, had been common for a long time. It was not dictated by nature. It was a strategy dictated by a need for order. So was marriage. There is no such thing as material wealth in nature (though there can be territories held by families). Marriage was a strategy for managing material wealth. Now though, it solves other problems as well. Marriage promotes social stability, partly by reducing reason for conflict. It reduces resources spent competing for females, though still a great deal of that is done. Now it becomes even more important as human development requires far greater resources, including education, for the extended development requirements associated with the complex modern world. Marriage that was invented as an economic strategy has become an extremely important moral strategy basically replacing polygyny and offering more resources for individual child development. Notice, strategy and choice have superseded instinct and simple biology. That is how humans can make it to the future.
Somewhere in here belongs a discussion of beauty. Beauty is a primary part of the feminine reproductive strategy. Beauty provides more choice of mates. There are two kinds of beauty. There is the beauty of health and form that indicates fertility which is obviously very desirable in the reproduction game. There is also the beauty that bends a male's mind. That is a form that has evolved to match idiosyncrasies of masculine attraction. It is literally beauty that is in the eye of the beholder or more accurately in the mind of the beholder. This is an important principle. It is a beauty that is deceptive or manipulative. It is not indicative of superior fertility. It is an adaptive response to how males perceive beauty that indicates fertility, but adjusted just a little to enhance that perception and cause an amplified response. It's weird and hard to understand and it can be very subtle, though there is one example that might illustrate the idea well enough to communicate it. Men are attracted to women's breasts. They are part of what indicate fertility and are a distinctly feminine trait. Men are programmed to respond to them visually. Well, sometimes men respond more strongly to larger breasts. (No, not all men and not all the time.) It's not that larger breasts are necessary for successful child raising, but they are just a stronger signal for males. It's the same signal, but amplified. At that point, they are the second kind of beauty, not practical for reproduction, but effective for attracting males, because of the programming of the male. It can be anything that may be perceived, the curve of a shoulder, the color of eyes, the softness of hair, etc. I remember the first time I noticed how beautiful a woman's legs could be. It is a subjective response though, programmed into the person experiencing and subject to change moment by moment and by circumstance. Many aspects of feminine beauty can be this way and a true artist of a plastic surgeon or makeup artist can sculpt stunning examples of this kind of beauty. It messes with men's minds (strongly manipulates) whether natural or created. this is a general principle of evolutionary biology that should be understood well. Like evolution, it is not about reason, it's about what works (or "what is"). I'm not going to guess how women respond to beauty, but clearly they do based on magazine content. As for masculine beauty, I'm not going to even guess, but obviously it exists and at its base is related to perceptions of superior genes.
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In a sense, as Sociobiology is the science of survival behavior, then this whole book could be about Sociobiology. This brief section is here partly to explain that moral instincts and moral systems are a study of science and it offers a lot of insight into the subject. Partly this essay is to cover the minimum foundation needed to lay out the importance of how our genes drive much of our survival behavior, that is moral behaviors. At the same time, our behavior is more than biology. We are transitioning between ecologies. We come from and are adapted to an ecology where polygyny and fighting is a better strategy, but we have already adapted and decided to limit the fighting and practice monogamy. Logically speaking it makes sense, because of the greater requirements needed for child raising now and the danger of violence to our society and civilization. In the future, we will be more genetically inclined that way, but now we have made the decision, a moral decision in order to survive. We are far more than our genes.