Our sense of fairness is an evolved part of our response to cooperative group living. Cooperation is very much a win-win proposition, but often some individuals will contribute more to a particular undertaking, and some individuals will receive more of the benefits. Our sense of fairness is an intuitive gut sense of whether the rewards are appropriate. This is closely related to the ideas of Cheating (breaking the rules) and freeloading (gaining a benefit that goes to all without having contributed.)
The most obvious way that rewards can be fair is if they are proportionate to the contribution, but other cultural rules are used, and can make a great deal of sense (be adaptive) given the means of subsistence of that particular people.
In a culture where hunting for large animals is an important food source, a kill is usually shared across the entire tribe. This is partly because it is impossible for the successful hunter to eat or preserve the entire animal before it spoils, but is also important as a way to protect the entire tribe from the risk of unpredictable and “lumpy” rewards.
If there is a successful kill every week or so, then there is enough to go around. The best hunter may be two or three times more productive than the least competent, but even the best hunter might starve if they had to rely purely on their own resources. There is a substantial element of luck in large-game hunting. This risk may only be tolerable if it is spread over the entire tribe. The scheme of sharing kills is analogous to “income redistribution” from the best hunters to the worst hunters. Although the best hunters may grumble about freeloaders, a successful culture will find ways to keep their high achievers sufficiently happy that they remain motivated.
What does the parable of this tribe illustrate about the human condition? Though there may be incidental fringe benefits, the most important benefit that goes to high achievers is probably the benefit that goes to all members of the society, which is the benefit of being in a viable polity that can successfully compete with other polities and which can undertake the large-scale projects that may be necessary for mere survival in the natural environment.
Then, as now, it remains largely a fantasy that high achievers could flourish by casting off the burden of supporting freeloaders.
People are highly motivated to compare themselves to others, both better off and worse off. Social Comparison Theory
People care a great deal about their relative standard of living (compared to others), not so much about their absolute standard, beyond a certain minimum of food, clothing and shelter.
people differ in their abilities and interests
some occupations and behaviors are socially highly rewarded (wealth, power and prestige.)
Why these things?
In different cultures, different things are rewarded. For example, in a pre-modern pacific island culture, it might be prestigious to be a good fisherman, navigator, or to be the best drummer. Fishing and other subsistence activities might be self-rewarding, but other roles are rewarded in ways that may seem arbitrary to us, but that make sense in that culture.
Our understanding of human nature should inform our political and economic ideas of fairness and distributive justice.
This debate is politically important because the laws and cultural norms that govern current societies award most positions of wealth, prestige and power to men. If there were no innate sex differences that were relevant to achieving these social rewards, then any inequality of outcomes must be caused purely by arbitrary cultural conventions. That would be obviously unfair.
This inequality persists even in western countries where women legally have the same rights and opportunities as men, where sex discrimination is banned in the workplace, and where politicians that advocate sexist views rarely get elected. Persistent inequality is surely partly because many people in influential positions still believe in distinct gender roles, and judge people as being more or less suited to some job or office based on their sex (sexual discrimination.)
However, some of the difference in outcomes is clearly due to choices that women make, such as what career to pursue and whether to suspend their career to raise children. Even if a woman decides on highly rewarded career and relies on others to take care of her children, she may make different decisions in work–life balance that put her at a competitive disadvantage in getting promotions.