One approach to deciding whether humans are basically good or evil is to infer what extremely early human behavior was like. What was the behavior and social structure of the earliest common ancestors of modern humans, about 150,000 years ago? What about our earlier social primate ancestors? Were these ancestors violent or peaceful? Did everyone had equal power within the social group, or did might make right?
Of course, no one knows what the behavior of prehistoric humans and proto-humans was. Since behavior doesn't fossilize, it is hard to see how we ever could know for sure. What scientists have done is study our closest non-human relatives, the Chimpanzee and Bonobo, and also living humans whose way of life is similar to our best guess of how early humans lived.
Why is early human behavior better evidence for human nature than how people behave now? Perhaps by looking at the behavior of ancestors we are getting more directly at the essence of human nature. In particular, culture has a huge role in shaping our behavior and social structure. It is very difficult to say, looking at human life today, what things are human nature and what are arbitrary cultural conventions.
When we look at our social primate cousins we can see an aspect of our natures without being confused by culture. While there is evidence that non-human primates can adopt useful behaviors and socialize others into these patterns, culture clearly plays a far smaller role that it does for humans. We argue that being The Cultural Animal is the most important defining characteristic of humanity, so any animal that lacks complex culture is not exactly human, but their behavior is the best evidence we have of proto-human behavior. Since evolution works by tinkering with that went before, a great deal of our common ancestors are still in us.
Especially fascinating is evidence that other social primates have moral emotional responses, such as to unfairness:
Yet humans are neither chimpanzees or bonobos; we see ourselves in them, but they can't tell us who we are. Our social primate nature has been augmented and overlaid by new mental structures.
Anthropology gives fascinating evidence about the vast diversity of human behavior and about the vast diversity of ways in which cultures shape our behavior into functioning social patterns. Any way that humans actually live today is clearly a possible way of living (at least under the right conditions). But how did our earliest ancestors live?
There is convincing archeological evidence that farming and agriculture don't date back more than about 10,000 years, so early humans weren't farmers or herders. They must have gotten their food by some combination of gathering plant foods, scavenging the carcasses of dead animals, and by hunting. People that live this way are called hunter-gatherers.
Among hunter-gatherer peoples that have been described by anthropologists, these groups tend to be:
Although there is no entirely convincing theory for why hunter-gatherer cultures should have these things in common, we can see how these behaviors and values are consistent with their lifeways. They form a synergistic whole, where each reinforces the other. Nomadism works well with hunter-gathering because it allows them to move on when food is exhausted. A nomad can't have many possessions because they have to carry them. Sharing works well with hunting, because kills are unpredictable, and meat must be eaten before it goes bad. Minimizing in-group conflict benefits any group. Sharing, egalitarianism, and lack of possessions reduce serious within-group conflict, and nomadism makes it easier for groups to split when there is conflict.
Why are hunter-gatherers egalitarian? You might think the answer is obvious: we humans would just as soon not have any big man lording it over us. But why do we feel that way? Evolutionary Psychology is largely about explaining why we have the emotions and motivations that we do. Since being anything other than a hunter-gatherer is relatively recent (on the time scale of genetic evolution), our innate emotions and motivations should be well adapted to that way of life.
The simplest answer is that hunter-gatherers don't need a leader (to resolve internal conflicts or lead war parties). In the hunter-gatherer life, everyone has to work to get enough to eat, and often has to work independently and take initiative. Egalitarianism is one way that a culture can manage Social Conflict. Evolutionary psychology predicts that individuals will be motivated to get more than an equal share of food or of sexual partners, but also predicts that nobody will want be on the losing side of within-group competition. An egalitarian social system reduces this conflict by setting the standard to be equality.
Yet a standard of equality does nothing if the rule isn't followed. Evolutionary psychology predicts that we will be watchful for signs that we are losing out. If we have to enforce fairness by fighting for our rights (as the monkey attempts in the video above), then we will only be treated fairly by those we can defeat in a fight. Since some are better fighters than others, this creates the Dominance Hierarchy usually seen in social primates. The solution that egalitarian human societies have hit on is social control–the group cooperates to enforce equality (see reverse dominance hierarchy). Although less drastic solutions are preferred, in hunter-gatherer groups there are always many hunters with excellent skills in using lethal weapons. Aspiring big men know that.
So are the behaviors of hunter-gatherer groups more virtuous than what we see in other societies? Certainly it is common enough for state societies (based on farming) to have high levels of social inequality, including hereditary nobility, to practice slavery and human sacrifice, to value fighting ability and to frequently attempt empire-building military conquest. That does create a lot of suffering.
Yet anthropologists are quite reluctant to declare one culture to be superior to another in any way, let alone to say that it is morally superior. We know what we think is moral, but other cultures don't entirely agree. Is it fair to judge them by our standards? Cultural Relativism says no.
Evolutionary Psychology provides a tricky way of generating an answer by turning this question around. It is likely our innate moral senses and motivations evolved to help us to function in hunter-gatherer groups with egalitarian social structures. As long as our social natures have not changed since then, living in a small egalitarian group would be the most natural way to live; it would “feel right” to us. For the past 5000 to 10,000 years almost everyone has been living in much larger, less equal, groups, where our moral sense doesn't quite line up with the social rules. This evolutionary mismatch has created millenia of nagging frustration.
The moral superiority of hunter-gatherer life isn't quite that clear-cut, though. First, although philosophers who study Ethics don't agree on much, they do agree that “feeling right” is not a sound way to decide what truly is right (see Evolutionary Ethics). Second, it is likely that peoples who have been through the meat-grinder of civilization have endured some fine-tuning of their motivational structures. Although evolution does tend to move slowly, if you are living in a despotic city-state you'd better develop some acceptance of social inequality, or you're going to die. This creates strong Selection Pressure, which can shift things pretty dramatically in 10 generations (300 years), or even less.
What about war? Are humans naturally violent, or peaceful? We don't really know how often tribes of early humans got into battles or whether they attacked other homnids (such as Neanderthals). We would expect that nomadic hunter-gatherers would rather move on than risk death in battle, as long as there was somewhere to move on to. Once we adopted farming, moving on was no longer an attractive option, so inter-group conflict increased. Inter-group conflict is also common in recent hunter-gatherers. Even before the rise of the state most of us were were worried about raids from neighboring tribes, and had to be prepared to fight. See The Better Angels of Our Nature for a book-length study of human violence.
So are humans basically good or evil? What has the study of human origins told us? We evolved as egalitarian hunter-gatherers, so that kind of social structure feels right to us. In recent millenia we've learned to tolerate some social inequality, gone on to invent new types of hierarchical organizations with overwhelming military and economic power, and picked up some new moral sentiments such as loyalty, respect for authority, and patriotism. We don't know how much of this change in the moral landscape is recent genetic evolution and how much reflects the flexibility of our moral mechanisms. The significant heritability of political attitudes and personality traits suggests that at least part of the story is genetic.
This explains how we got to be the way we are, and why we are fascinated by hunter-gatherer lifeways, but what has looking at the beginning told us about ourselves, as we are now? Whether humans are innately good or bad today depends on our current nature, which is at least slightly different than how we were back then. Were we corrupted by civilization? Or has change between then and now has been almost entirely Cultural Evolution? Then, if we could find an empty corner of the planet with adequate abundance for hunting and gathering, we could go back to living the way that humans were designed to live.
Stories about whether humans are inherently good or evil are myths. Fascinating, but neither true nor false. See Good Or Evil?.