An Evolutionary View of Humans 4: Sharing

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One of the biggest differences between our nearest living relatives (The common chimpanzee, Pan troglodytes) and humans is our unique sense of the importance of a social contract. We have a concept of ownership, possession, exclusivity of access, etc. when it comes to material goods such as tools or resources, and of course, sexual relationships. It has been argued that this is a feature that can be found in primates. In a classic series of experiments done by Kummer with baboons, he showed that one male baboon perceived an ongoing sexual liaison between another male and a particular female. As long as the paired male was in sight, the focal baboon would not make sexual advances towards the paired female even though she was in a state of sexual receptivity. This was the case even when the focal male and the paired female were enclosed in a cage together, with the paired female enclosed in a different cage a safe distance away. Similar observations have been made in other primates including chimpanzees in captivity and in the wild.

However the presence of a vague ability to perceive danger … that you will likely be severely attacked by a large male under certain circumstances is expected in social primates. What Kummer’s experiment may really demonstrate is that baboons don’t get cages.

The evolution of a sophisticated mechanism or set of mechanisms in hominids (humans and their upright ancestors) that elaborates on this capacity is what we would expect from an evolutionary perspective. We are upright using our hind limbs exclusively for locomotion, and thus different from other apes, but at the same time the nature of our uprightedness (that we can also use overhead bars and straps on a bus or subway for stability, for instance) is a feature of our positional behavior that relates directly to the fact that apes tend to suspend below branches rather than walk atop them (as to Old World monkeys).

In other words, I don’t think that a trait observed in one species is not unique and not the result of adaptive evolution just because a mild form of the trait is observed in other closely related form. Such a situation … total uniqueness … is simply not expected most of the time.

Tropical and subtropical human forager groups all exhibit what we call a “sharing ethic.” Typically, this is manifest as social rules whereby if one person asks another for a particular thing, it is simply given. Both stinginess and gloating (over possession of something) are culturally proscribed. A person is judged by others on the basis of many things, but near the top of the list is a strong sharing ethic. It is even likely that people show off by trying to be the better sharer.

From a biological perspective it is thought that sharing is necessary in foraging societies because the nature of foraging is such that no one individual can maintain a sufficiently consistent food supply over medium to long term on the basis of their own efforts. Only by sharing, whereby one person with a surplus distributes that surplus one day, and in return benefits from the largess of others, can an individual avoid periods of starvation that would sometimes last days or weeks (and thus possibly be fatal).

This argument, however, is weak on its own, because most (all?) tropical and subtropical foragers do have access most of the time to resources that are consistent over long periods. In most of these groups, females are able to obtain in a given day sufficient food for their immediate needs and the needs of their offspring. Males, on the other hand, tend to forage for resources that result in occasional abundance dispersed among days of an inadequate supply. Were humans to stop sharing in these groups, this could work out as long as everybody (males included) foraged in the female style.

However, the resources that males tend to obtain from the wild (mainly meat from hunting), despite their irregularity, may serve a critically important role – or more than one role. For example, basic cellular function, especially as related to growth and the immune system, require the synthesis of many proteins that are built from amino acids. Some of these amino acids are synthesized in cells, others are not and must be ingested … typically in the form of proteins in a variety of plant foods as well as animal foods. the amino acids are not interchangeable. Almost all proteins are made from a list of 20 amino acids that occur in varying degrees of abundance in various plant foods. If you eat only plant foods, there will always be one amino acid that is the rarest of those needed, so you must ingest a larger than optimal quantity of foods. But if you eat meat, you are ingesting a perfectly balanced set of amino acids. In other words, a very efficient way of maintaining your body is to eat other animal bodies.

So, it may turn out that the highly variable sources of “balanced” proteins … mainly meat from hunting … are a critical resource for this (and other) reasons. So while day to day energy needs cannot be met among these forager groups from hunting (that comes mainly from the plant foods), the needs of growth and immune system function and general cellular processes can be met with this variable food supply. But only if it is shared.

The problem this presents is actually psychological (or maybe I should just say neurological … brain based). Apes don’t share much. When chimpanzees forage … and they typically forage for rare, high quality foods … they benefit by foraging alone because this reduces competition with other chimpanzees. They do not bring the food they find to any other place than where they found it in order to consume it.

In contrast, human foragers do two critically important things. First, they bring much of the food they forage to a central place … the forager “camp” as we call it. Since all the foragers in a given group (by definition) live in the same camp, they are therefore bringing this food into direct competition with other foragers. If they were chimps, the dominant chimps would just take the food from the lower ranked chimps, or small coalitions of cooperating individuals (usually males) would take any of the food they wanted from any of the other chimps.

The second thing foragers do is they process much of this food. This processing is often essential to make these food items edible. In other words, human foragers are finding items (plant parts) that are not edible by humans … and thus constitute a kind of VERY low quality food (zero or near zero caloric value) and by processing — including cooking with fire — turn this stuff into medium or high quality food.

The only way to do this second thing (turning the inedible into the edible) is to do the first thing … to have a central place foraging style. And the only way to do this is to have a social ethic that manages the concepts of possession, ownership, sharing, and so on.

How does this ethic emerge in an individual? A little introspection and reference to experience can help answer that question. Sharing, being fair (the opposite of “cheating”), a capacity to learn and live by certain social ethics and so on emerge over several years in children with the continuous, time consuming, and energetically costly efforts of adults.

What are the social mechanisms that are at work in this aspect of childrearing?

Are there ways in which adults, who are at a stage in their lives when they are looking for possible mates, evaluate each other with respect to these behavioral qualities? Are there aspects of the human dating/mating/marriage rituals and patterns that demonstrate this?

Are there ways in which adults demonstrate these qualities, and if so, how do others ascertain if these demonstrations are false vs. honest indicators of a sharing ethic?

How does this play out in social relationships other than mating/marriage?

Are there conditions in which sharing is the inappropriate behavior? If so, how do individuals or subsets of society balance a sharing ethic and what might be called a selfish ethic?

Do the manifestation of these behaviors vary across age and gender, or social class?

Humans are different from chimps in these critical aspects of behavior, and these differences are manifest in both ecological and reproductive aspects of human culture and society. Modern foragers demonstrate the human condition, and the way in which these problems have been solved through adaptive behaviors. What kinds of problems emerge in other kinds of human societies that have emerged only recently in human prehistory, such as agricultural societies where the value of land on which food is grown, or the efforts put into crop tending, create a new kind of resource … immobile, big, and vulnerable. What kinds of problems emerge in pastoral (i.e., cattle-keeping societies) in which the key resource is potentially VERY mobile, but still big and vulnerable? What are the resources that Western Industrial societies rely on and how is that managed? In other words, what would a list of evolutionary discordances … differences between the normal foraging way of life and other ways of life … look like?

Next Item in the Series: The Opposite Sex

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