The extent of our dependence on others’ ideas and labor becomes obvious when you imagine trying to recreate your belongings stranded alone on an island. Who knows how to build a bicycle, let alone a car, and even if you did, how would you obtain the raw materials to do it? Even growing your own food depends on prior knowledge of principles discovered by your ancestors. Our scenario-building minds draw heavily on the ideas and experience of other minds to guide our own future. Our modern means of communication allow us to cooperate with virtually anyone anywhere on the planet.
Other animals cooperate, too. Symbioses are widespread. For example, you are host to millions of bacteria that could not do without you, nor could you do without them. In fact, bacteria outnumber human cells in your body. They do a job for you, and you provide them with a fine habitat. Symbiosis is common, as long as the benefits outweigh the costs. Some animals even take what appear to be considerable risks in their cooperation. Cleaner fish eat parasites out of the mouths of larger fish, which in turn do not swallow them. Some ants protect aphids (plant lice) from predators and even store their eggs. In return, the ants get to milk the aphids for honeydew.
Cooperation between members of the same species is similarly widespread. Ants, like other social insects, demonstrate large-scale cooperation. The reason they do this, ultimately, is that they are all closely related. A bee may sting an attacker and die, but its individual sacrifice increases the chances of survival and reproduction of its hivemates (and genetic line). Such species act, in some sense, as one super-organism. Naked mole rats are a mammalian species that follows a similar strategy. A queen reproduces with the help of a couple of males, whereas workers do all the other jobs around the burrow. Though the workers do not reproduce themselves, their actions increase the fitness of their reproducing relatives.
The evolutionary biologist William D. Hamilton suggested it is not the number of viable offspring per se that matters in evolution, but the genes that make it into the next generation. Since we share genes with our relatives—you share at least 50 percent of your genes with each of your siblings, children, and parents; 25 percent with half siblings, grandchildren, aunts/uncles, and nephews/nieces; 12.5 percent with first cousins; and so forth2—the frequency of our genes in the next generation is determined in part by the reproductive success of our relatives. If your behavior can aid your relatives’ fitness, it may be selected even if it is costly to you. Hamilton proposed a rule about when costly behavior is compensated by benefits to relatives.3
Cooperation between relatives can therefore be explained by kin selection. Consider how much pain you would be prepared to suffer for a given family member. To do this, sit as if you were sitting on a chair while leaning against the wall, with no chair, legs bent at 90 degrees. Try to hold this position for as long as possible. You’ll find that it is easy at first but will become painful the longer the position is held. Some enterprising, and possibly cruel, researchers used this exercise to quantify how much people were willing to hurt for their family, by promising participants more money the longer they could hold the position. If the money was for the participant, they ended up holding on the longest. If the money was for a relative, people held on according to how closely related they were. They held the position longer for a parent or sibling than for an aunt or grandparent. They held on less still for a cousin and the least for an unrelated person. Such behavior is exactly what would be predicted from the kin selection perspective.
You may well object that there are exceptions.4 For instance, you may have decided not to suffer at all anymore for a particular family member. You may well be willing to help close friends much more than you would be willing to help any of your relatives. The experimental results above, as well as corroborating ones, are only averages, so exceptions may be accommodated. Still, it is clear that not all human cooperation can simply be explained in terms of kin selection because we evidently cooperate extensively with people to whom we are not particularly closely related. It is this cooperation with nonrelatives that appears to be unusual in the animal kingdom and is essential for explaining human societies and cultures.
The sociobiologist Robert Trivers proposed that we cooperate with nonkin largely in expectation that the favor will be reciprocated in the future: I’ll scratch your back if you scratch mine. The return of the favor need not be immediate, and payment may be indirect—for instance, through money. In other words, we might have evolved to be so helpful because we ultimately get something back in return.
But is all our helping so selfish? People sometimes give generously without expecting anything in return. This is a virtue of which we are typically quite proud. I was not related to any of the people who gave me lifts as a hitchhiker. When a natural disaster strikes, people donate time and money—with little potential for reciprocity. During the process of writing this book, our house in Brisbane, like more than twenty thousand others, was severely flooded. Friends, neighbors, and countless strangers helped us shovel the mud out of the house, tear down the soaked walls, and clean what was salvageable. Someone even gave us a washing machine. It’s extraordinary how humans can pull together in times of crisis, creating a sense of indomitable community (and faith in the power of the human spirit). I do not recall a single argument or conflict, and we had some laughs in spite of it all. History is full of compassionate, selfless, and heroic actions. People are capable of sacrificing time, effort, and sometimes even their lives—all for the sake of helping others.
Nonetheless, many philosophers and economists question whether true altruism exists. They argue that the apparent altruists always benefit, or they think they benefit, in some way or another. Such a view may appear uncharitable, but it is certainly true that helping others may secure you future support. Your house may be flooded or hit by an earthquake in the future. People may not consider this factor at the moment they decide to help and simply act out of compassion. However, the tendency for selfless giving may have evolved because those who did act altruistically on average ended up benefitting (or at least their relatives did), even if they did not consciously seek benefits.5 For example, people who help a lot gain a good reputation, which in turn can bring advantages, and not only from those who were helped directly.
Many people believe in some sort of karma—a general cosmic rule that what goes around comes around. Various religions promise some personal account keeping and payback or reward, if not here, then in an afterlife. This encourages helping behavior but also turns even the most generous, selfless acts into something that is fundamentally self-serving. I’d like to think that humans are not merely selfish, yet I do not know of conclusive evidence against such ultimate explanations, and my liking or disliking the idea is, sadly, irrelevant. Be that as it may, we can probably agree that in the long run most of us expect some kind of return for our giving. When the balance between giving and receiving gets too out of balance, most of us become rather irritated.
A notorious problem for reciprocal altruism, then, is that individuals may cheat. There are always takers who do not give anything in return. Whether you call them leeches, parasites, freeloaders, or some more offensive term, we tend to bristle at people who take advantage of us—and we may seek retribution. Extreme freeloaders may be called sociopaths. They are characteristically irresponsible, unreliable, and egocentric, taking advantage of others’ goodwill by exploiting their prosocial tendencies. In small societies people quickly learn to mistrust and stop cooperating with those with a reputation for cheating. In today’s large, mobile societies, however, sociopaths may sometimes move from one group to another and start afresh. Yet freeloading is not only a trait of people you dislike. In fact, humans often cooperate in one context and cheat in another. For example, many otherwise prosocial people will proudly state how they avoid paying taxes (which, of course, is cheating everybody in the country). Violations of reciprocal altruism may range from small, simple oversights to large-scale exploitation—from not doing the dishes to thieving, from
assault to invasion.
Because of the problem of cheating, it has been hotly debated how cooperation among nonrelatives could have possibly become common practice in the first place. As Dawkins argued so persuasively, from a genetic perspective we are hosts to selfish genes that try to replicate themselves either directly or via our kin. If this is correct, then cooperation should only work in the long run if it benefits our genes. Cooperative systems are always under threat from freeloaders because they get the benefits without having to pay the cost. So freeloaders should win, and their genes should spread more than those of the cooperators—leading to the ultimate collapse of cooperation. Human societies managed to overcome this problem, even if they are evidently not immune to abuse. We developed means to detect, punish, and deter cheating.6 Groups established effective ways of encouraging and enforcing cooperation. We managed to cooperate reasonably consistently and, eventually, on a large scale.
With our already discussed capacities for problem solving, mind reading, time traveling, and exchanging our minds, humans can agree on shared sets of rules in everybody’s mutual long-term interest. For instance, we may agree on the rule that if you want to take certain things from someone, you need to ask permission. Today, in most societies governments have turned cooperative rules into written laws. Police enforce these rules, judges determine punishment for transgressions, and legions of lawyers argue about what you can get away with. In principle, the important thing is that violations of rules need to be identified and addressed. Repeated or severe transgressions typically attract harsher consequences, such as exclusion from the group through banishment or death. But gossip and public shame are usually powerful enough deterrents, especially in small groups, because cooperators, for obvious reasons, would rather interact with other cooperators than with cheats. Who wants to hang out with, and rely on, someone who will cross you? People therefore work to clear their names if wrongfully accused, and one’s honor is of paramount importance. Reputation matters. It allows for “indirect reciprocity,” in which other group members bestow benefits on those who cooperate consistently and costs on those who do not.
We internalize rules of conduct and monitor and evaluate our own and others’ behavior accordingly. Our morality is fundamental for effective cooperation with nonrelatives. We will look at this in more detail in the next chapter, but for now I’ll simply note that through cooperative rules humans have been able to establish flourishing, cooperative societies. The big prize this persistent cooperation brought is that our ancestors could complement genetic evolution with a powerful new way of rapidly meeting adaptive challenges: cultural inheritance.
YOUR SCHOOLING WAS DESIGNED FOR the acquisition of cultural knowledge, which was accrued over many generations and deemed important to teach the next generation. Even without formal schooling, every human group passes on cultural heritage. Obviously, groups differ in their traditions (e.g., Australians play the didgeridoo and Austrians the alphorn), but they all discovered or invented thousands of tunes, symbols, technologies, and customs passed on from one generation to the next. Each new generation then builds on this heritage. The capacity for this kind of cumulative culture appears to be universally human. Michael Tomasello argues it is also uniquely human:
New forms of cultural learning created the possibility of a kind of ratchet effect in which human beings not only pooled their cognitive resources contemporaneously, they also built on one another’s cognitive inventions over time. This new form of cultural evolution thus created artifacts and social practices with a history, so that each new generation of children grew up in something like the accumulated wisdom of their entire social group, past and present.
We all stand on the shoulders of giants7—or, rather, we stand on the shoulders of millions of ordinary, mostly dead people from whom we inherited our culture. We have evolved a fast and flexible way to pass on information to the next generation. What worked well in the past is maintained until something more suitable comes along. Cumulative culture has a role in most of what we do: it shapes our minds and is essential for explaining how we have transformed the Earth. It is evident in architecture, arithmetic, ceremonies, clothes, conversations, crafts, cuisines, customs, dance, games, infrastructure, mating rituals, music, philosophy, public performances, rites of passage, science, spirituality, stories, and technologies—among other areas. If the mechanisms of cumulative culture are unique, then they would explain much of the apparent uniqueness of the items on this list.
The most important characteristic of human culture, then, is that it acts as a second inheritance system, in addition to genetic inheritance. Like genes that were selected because they gave individuals an adaptive advantage, cultural information can have distinct survival and reproductive benefits. One obvious advantage of cultural evolution is that it enables us to adapt much faster than we ever could biologically. And this might have given us an additional edge over other creatures. In response to a sudden onset of an ice age, people could simply make warmer clothes, whereas gradual biological selection for thicker fur takes many generations—and much chilly suffering. Richard Dawkins suggests that cultural evolution is based on the replication of what he called “memes” (in analogy to genes), such as ideas, behaviors, or tunes that spread from one person to another. While there are heated debates about the precise similarities and differences between cultural and biological evolution,8 the important point is that cultural knowledge can make a difference to survival and reproduction and hence can influence biological evolution itself.
Cultural knowledge evolves in response to local demands. Aboriginal Australians living in the dry center of the continent managed to eke out a living because they knew how to find water and food. Even the wisest among them would probably perish if suddenly transported into the northern arctic. The Inuit, by contrast, have managed to hunt with the limited materials available in the Arctic and devise ways to stay warm. Yet an Inuit would probably fare no better than our transported Aboriginal person were she to suddenly find herself alone in the Australian desert. (I would no doubt perish in either place.) Relevant local cultural knowledge is essential for human survival in diverse habitats.
Whereas culture used to be extremely localized, written language and modern information channels enable us today to rapidly exchange knowledge across the globe. Perhaps it is now possible for a single person to accumulate the tools and knowledge necessary to survive in all manner of harsh environments. Before such opportunities for mass distribution of “memes” existed, however, they must have been transmitted person to person. Cultural forms fit local functions (just as Darwin observed that biological form fits function—to raise a parallel to biological evolution). Each generation must have learned exactly how the solution to a problem worked and passed it on—if not, it was lost.9 One generation not speaking the language of their parents can mean, and has often meant, that the language dies out. Unlike recessive genes, social learning could not lie dormant for a generation (to raise a difference from biological evolution). It was crucially important that all the significant “memes” are transmitted reliably and with sufficient accuracy.
To achieve high-fidelity social learning in the absence of written language, humans had to rely on two processes. Information is passed on either with the intent of the possessor or with the intent of the receiver. Teaching and imitation are the two recognized pillars of human cultural inheritance. Each new generation acquires the material, social, and symbolic traditions of its group in these ways.
IMITATION IS WIDESPREAD. YOU MIGHT not admit to it, but you copy what others say, what they wear, and what they do. For culture to be transmitted across generations it is essential that children reliably imitate. In fact, humans demonstrate the first signs of a capacity for imitation from birth. When you stick your tongue out at a newborn, there is a chance that the baby will do the same back to you. It is unclear how this earliest copying is related to later imitative abilities, but it certainly encourages adults to copy th
eir babies in attempts to socially engage.
By nine months infants can copy novel actions and thus acquire new skills. For instance, through observation they may learn how to combine a couple of objects to make a rattle. As we saw in Chapter 5, they retain this new knowledge and can later make rattles from similar objects. By one year, infants begin to imitate rationally: when they copy actions, they appear to take the model’s situation into account. In one study infants saw an adult use his head rather than his hand to turn on a light switch, and they copied the act. In another condition in which the model had his arms tied behind his back, and there was hence a rationale as to why he did not use his hands to turn the light on, the infants instead used their hands to turn on the light. They seemed to understand what the model was trying to achieve and what he could do in the circumstances. From about eighteen months onwards, imitation often becomes a favorite past-time. Toddlers engage in sustained imitation games with older children and adults, taking turns copying and being copied.
When my colleague Mark Nielsen showed twelve-, eighteen-, and twenty-four-month-old children how to open puzzle boxes with a tool to get at a reward, they could all do it. Yet while the younger children simply used their hands to open the boxes, the older children imitated the use of the tool—even though they could have more easily opened it with their hands. When twelve-month-olds first see a model unsuccessfully attempting to open the box with their hands and then resort to tool use, the infants also choose to use the tool rather than their hands. Thus they imitate tool use when there is a rational reason to copy the exact actions. Only the older toddlers, however, copy even when there is no obvious reason to act in the more complex way. In a sense the younger infants’ strategy appears to be smarter: they copy the most efficient way to solve a problem, whereas the older toddlers “overimitate”—that is, they also copy superfluous actions. Yet there must be other reasons driving the older toddlers’ imitation. Why else would they put in the extra effort?
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