“In the beginning, all people lived around a great ironwood tree in the jungle, speaking the same language. One man whose testes were enormously swollen from infection with a parasitic worm spent his time sitting on a branch of the tree, so that he could rest his heavy testes on the ground. Out of curiosity, animals of the jungle came up and sniffed at his testes. Hunters then found the animals easy to kill, and everyone had plenty of food and was happy.
“Then, one day, a bad man killed a beautiful woman’s husband, in order to get the woman for himself. Relatives of the dead husband attacked the murderer, who was defended in turn by his own relatives, until the murderer and his relatives climbed into the ironwood tree to save themselves. The attackers tugged on lianas hanging from one side of the tree, in order to pull the tree’s crown down towards the ground and get at their enemies.
“Finally, the lianas snapped in half, causing the tree to spring back with tremendous force. The murderer and his relatives were hurled out of the tree in many different directions. They landed so far away, in so many different places, that they never found each other again. With time, their languages became more and more divergent. That is why people today speak so many different languages and cannot understand each other, and why it is hard work for hunters to catch animals for food.”
That story was related to me by Sikari people, a tribe of six hundred New Guineans. The story exemplifies a widespread class of myths called origin myths, familiar to us through accounts of the Garden of Eden and the Tower of Babel in the Bible’s Book of Genesis. Despite those parallels with Judeo-Christian religions, traditional Sikari society lacked churches, priests, and sacred books. Why is the Sikari belief system so reminiscent of Judeo-Christian religions in its origin myth, yet so different in other respects?
All known human societies have had “religion,” or something like it. But what really defines “religion”? Scholars have been debating this and related questions for centuries. For a belief system to constitute a religion, must it include belief in a god or gods, and does it necessarily include anything else? When, in human evolutionary history, did religion appear? Human ancestors diverged from the ancestors of chimpanzees around six million years ago. Whatever religion is, we can agree that chimps don’t have it, but was there already religion among our Cro-Magnon ancestors of 40,000 years ago? Were there different historical stages in the development of religions, with creeds like Christianity and Buddhism representing a more recent stage than tribal belief systems like that of the Sikaris? These longstanding questions have become acute to all of us reeling from recent terrorist attacks, and struggling to comprehend the fanaticism that drove them. We tend to associate religion with humanity’s noble side, not with its evil side: Why does religion sometimes preach murder and suicide?
If we are to answer these questions, David Sloan Wilson tells us in Darwin’s Cathedral, we must recognize that religions are human institutions and belief systems evolving by the process which biologists term “group selection.” Religions potentially offer practical, social, and motivational benefits to their adherents. But religions differ among themselves in the degree to which they motivate their adherents to have children, to rear those children to become productive members of society, and to convert or kill believers in competing religions. Those religions that are more successful in these respects will tend to spread, and gain and retain adherents, at the expense of other religions. Two quotations from Wilson’s book will serve to summarize his thesis:
Something as elaborate—as time-, energy-, and thought-consuming—as religion would not exist if it didn’t have secular utility. Religions exist primarily for people to achieve together what they cannot achieve alone. The mechanisms that enable religious groups to function as adaptive units include the very beliefs and practices that make religion appear enigmatic to so many people who stand outside of them.
Demographic change in a population depends upon births, deaths, immigration [i.e., conversion in the case of religion], and emigration [i.e., abandoning one’s religion]. The balance of these inputs and outputs must be positive for any religion to persist, but their relative importance can vary widely. As one extreme example, the Shakers were successful for a brief period of time based purely on immigration, and without any births. Based on immigration alone, Judaism is at a large disadvantage compared to proselytizing Christian and Islamic religions, which accounts in part for its minority status. Despite its disadvantage with respect to immigration, however, Judaism has persisted on the strength of the other factors that contribute to demographic growth (high birth rate, low death rate, and low emigration).
Wilson introduces his argument with two chapters examining religion from the twin perspectives of group evolutionary biology and the social sciences. The next four chapters test his hypothesis against some actual religions: early Calvinism, Bali’s water temple system, Judaism, the early Christian Church, the Houston Korean Church, and the Christian doctrine of forgiveness. These discussions are full of new perspectives on institutions seemingly so well known that one might think there was nothing new to say about them.
For example, why, among the innumerable tiny Jewish sects competing with each other and with non-Jewish groups within the Roman Empire in the first century AD, did Christianity emerge as the dominant religion three centuries later? Early Christianity’s distinctive features contributing to this result included its active proselytizing (unlike mainstream Judaism), its practices promoting having more babies and enabling more of them to survive (unlike contemporary Roman society), its opportunities for women (in contrast to contemporary Judaism and Roman paganism and to later Christianity), its social institutions resulting in lower death rates of Christians than of Romans from plagues, and the Christian doctrine of forgiveness. That doctrine, which is often misunderstood as the simplistic notion of indiscriminately turning the other cheek, actually proves to be part of a complex, context-dependent system of responses ranging from forgiveness to retaliation. Under certain circumstances, experimental tests carried out by playing simulated games show that forgiving someone who has done you one wrong may really be the response most likely to gain you advantages in the future.
Obviously, the main subject of Darwin’s Cathedral—religion—is widely contentious. In addition, many of the subjects on which Wilson draws to interpret religion—subjects such as group selection, adaptation, hypothesis testing, and how to “do” science— are contentious among scientists. Discussions of these subjects tend to be partisan, oversimplified, and riddled with misstatements. A great virtue of Wilson’s book is the scrupulous fairness with which he treats controversial matters. He is careful to define concepts, to assess both their range of applicability and their limitations, and to avoid posturing, misrepresentations, exaggerated claims, and cheap rhetorical devices. Thus, Wilson’s book is more than just an attempt to understand religion. Even to readers with no interest in either religion or science, his book can serve as a model of how to discuss controversial subjects honestly.
It seems to me that what we think of as “religion” encompasses four different, originally unrelated, elements: explanation, standardized organization, moral rules of good behavior toward in-groups, and (all too often) rules of bad behavior toward out-groups. Those elements served different functions; they appeared or began to disappear at different times in human history; and they came together only within the last eight thousand years. Most efforts to define religion begin with one element: belief in a god or gods. But that definition immediately plunges us into difficulties, as Wilson notes:
Religion is sometimes defined as a belief in supernatural agents. However, other people regard this definition as shallow and incomplete. The Buddha refused to be associated with any gods. He merely claimed to be awake and to have found a path to enlightenment.
Some Jews and Unitarians as well, and many Japanese people, are agnostics or atheists but still consider themselves to belong to a religion. Conversely, many tribal societies believe in agents that we Westerners think of as spirits rather than as gods. What do these agents have in common?
An essential feature shared by the Judeo-Christian God, ancient Greek gods, and tribal spirits could be formulated as follows: “a postulated supernatural agent for whose existence our senses can’t give us evidence, but which is invoked to explain things of which our senses do give us evidence.” Quite a few Americans today believe God to be a “first cause” that created the universe and its laws and explains their existence, but that let the universe run thereafter without divine interference. Creationists invoke God to explain a lot more, including the existence of every plant and animal species, but most creationists wouldn’t invoke God to explain every sunrise, tide, and wind. Yet the ancient Greeks did invoke gods or supernatural agents to explain sunrises, tides, and winds. The New Guinean societies in which I have lived go further and have supernatural explanations for the songs of each bird species (as the voices of former people transformed into birds).
Clearly, in modern Western society religion’s explanatory role has gradually become usurped by science. Where Sikaris and Old Testament believers invoke origin myths (like the ironwood tree and the Tower of Babel) to explain linguistic diversity, modern linguists instead invoke historical processes of language change. Explanations of sunrises, tides, and winds are now left to meteorologists and astronomers. For modern scientists, the last bastion of religious explanation is God-as-First-Cause: science still has nothing to say about why the universe exists at all. From my freshman year at Harvard in 1955, I recall the great theologian Paul Tillich defying his class of hyper-rational undergraduates to come up with a scientific answer to his simple question: “Why is there something, when there could have been nothing?”
Besides a belief in God, a second defining feature of religions that we take for granted is standardized organization. Most modern religions have full-time priests (alias rabbis, ministers, or whatever else they may be called) who receive either a salary or else life’s necessities. Modern religions also have churches (alias temples, synagogues, mosques, etc.). Within any given sect, all those churches use standardized sacred books (Bibles, Torahs, Korans, etc.), rituals, art, music, architecture, and clothing. None of those features applies to New Guinea tribal beliefs.
Historically, those organizational features of religion arose to solve a new problem emerging as ancient human societies became richer and more populous. In recent times all Europeans have lived under political systems termed states, which European scholars initially assumed to be the natural form of political organization. But after 1492 AD, as Europeans spread over the world, they encountered peoples living under simpler and less populous political systems variously termed chiefdoms, tribes, and bands. From buried artifacts preserved at archaeological sites (such as recognizable trappings of chiefs and kings), archaeologists infer that the first chiefdoms emerged from tribal societies in the Fertile Crescent of western Asia around 5500 BC, and that the first states with kings emerged from chiefdoms around 3500 BC.