Living along the Orioco River that borders Brazil and Venezuela are the Yanomamö people, hunter-gatherers whose average annual income has been estimated at the equivalent of $90 per person per year. Living along the Hudson River that borders New York State and New Jersey are the Manhattan people, consumer- traders whose average annual income has been estimated at $36,000 per person per year. That dramatic difference of 400 times, however, pales in comparison to the differences in Stock Keeping Units (SKUs, a retail measure of the number of types of products available), which has been estimated at 300 for the Yanomamö and 10 billion for the Manhattans, a difference of 33 million times!

How did this happen? According to economist Eric D. Beinhocker, who published these calculations in his revelatory work The Origin of Wealth (Harvard Business School Press, 2006), the explanation is to be found in complexity theory. Evolution and economics are not just analogous to each other, but they are actually two forms of a larger phenomenon called complex adaptive systems, in which individual elements, parts or agents interact, then process information and adapt their behavior to changing conditions. Immune systems, ecosystems, language, the law and the Internet are all examples of complex adaptive systems.

In biological evolution, nature selects from the variation produced by random genetic mutations and the mixing of parental genes. Out of that process of cumulative selection emerges complexity and diversity. In economic evolution, our material economy proceeds through the production and selection of numerous permutations of countless products. Those 10 billion products in the Manhattan village represent only those variations that made it to market, after which there is a cumulative selection by consumers in the marketplace for those deemed most useful: VHS over Betamax, DVDs over VHS, CDs over vinyl records, flip phones over brick phones, computers over typewriters, Google over Altavista, SUVs over station wagons, paper books over e-books (still), and Internet news over network news (soon). Those that are purchased “survive” and “reproduce” into the future through repetitive use and remanufacturing.

As with living organisms and ecosystems, the economy looks designed — so just as humans naturally deduce the existence of a top-down intelligent designer, humans also (understandably) infer that a top-down government designer is needed in nearly every aspect of the economy. But just as living organisms are shaped from the bottom up by natural selection, the economy is molded from the bottom up by the invisible hand. The correspondence between evolution and economics is not perfect, because some top-down institutional rules and laws are needed to provide a structure within which free and fair trade can occur. But too much top-down interference into the marketplace makes trade neither free nor fair. When such attempts have been made in the past,, they have failed — because markets are far too complex, interactive and autocatalytic to be designed from the top, down. In his 1922 book, Socialism, Ludwig von Mises spelled out the reasons why, most notably the problem of “economic calculation” in a planned socialist economy. In capitalism, prices are in constant and rapid flux and are determined from below by individuals freely exchanging in the marketplace. Money is a means of exchange, and prices are the information people use to guide their choices. Von Mises demonstrated that socialist economies depend on capitalist economies to determine what prices should be assigned to goods and services. And they do so cumbersomely and inefficiently. Relatively free markets are, ultimately, the only way to find out what buyers are willing to pay and what sellers are willing to accept.

Evonomics helps to explain how Yanomamö-like hunter-gatherers evolved into Manhattan-like consumer-traders. Nineteenth-century French economist Frédéric Bastiat well captured the principle: “Where goods do not cross frontiers, armies will.” In addition to being fierce warriors, the Yanomamö are also sophisticated traders, and the more they trade the less they fight. The reason is that trade is a powerful social adhesive that creates political alliances. One village cannot go to another village and announce that they are worried about being conquered by a third, more powerful village — that would reveal weakness. Instead they mask the real motives for alliance through trade and reciprocal feasting. And, as a result, not only gain military protection but also initiate a system of trade that — in the long run — leads to an increase in both wealth and SKUs.

Another battle has broken out in the century-long “anthropology wars” over the truth about human nature. Journalist Patrick Tierney, in his book dramatically entitled Darkness in El Dorado: How Scientists and Journalists Devastated the Amazon, purportedly reveals “the hypocrisy, distortions, and humanitarian crimes committed in the name of research, and reveals how the Yanomami’s internecine warfare was, in fact, triggered by the repeated visits of outsiders who went looking for a ‘fierce’ people whose existence lay primarily in the imagination of the West.”

Tierney’s bête noir is Napoleon Chagnon, whose ethnography Yanomamö: The Fierce People is the best-selling anthropological book of all time. Tierney spares no ink in painting him as an anthropologist who sees in the Yanomamö a reflection of himself. Chagnon’s sociobiological theories of the most violent and aggressive males winning the most copulations and thus passing on their genes for “fierceness,” Tierney says, is merely a window into Chagnon’s own libidinous impulses.

Are the Yanomamö the “fierce people”? Or are they the “erotic people,” as described by French anthropologist Jacques Lizot, another of Tierney’s targets? The problem lies in the phrasing of the question. Humans are not easily pigeonholed into such clear-cut categories. The nature and intensity of our behavior depend on a host of biological, social and historical variables. Chagnon understands this. Tierney does not. Thus, Darkness in El Dorado fails not just because he didn’t get the story straight (there are countless factual errors and distortions in the book) but because the book is predicated on a misunderstanding of how science works and of the difference between anecdotes (on which Tierney’s book is based) and statistical trends (on which Chagnon’s book depends).

To be sure, Tierney is a good storyteller, but this is what makes his attack on science so invidious. Because humans are storytelling animals, we are more readily convinced by dramatic anecdotes than by dry data. Many of his stories enraged me … until I checked Tierney’s sources myself.

For example, Tierney accuses Chagnon of using the Yanomamö to support a sociobiological model of an aggressive human nature. Yet the primary sources in question show that Chagnon’s deductions from the data are not so crude. Even on the final page of his chapter on Yanomamö warfare, Chagnon inquires about “the likelihood that people, throughout history, have based their political relationships with other groups on predatory versus religious or altruistic strategies and the cost-benefit dimensions of what the response should be if they do one or the other.” He concludes: “We have the evolved capacity to adopt either strategy.” These are hardly the words of a hidebound ideologue bent on indicting the human species.

The fourth edition of Chagnon’s classic carries no subtitle. Had he determined that the Yanomamö were not “the fierce people” after all? No. He realized that too often people “might get the impression that being ‘fierce’ is incompatible with having other sentiments or personal characteristics like compassion, fairness, valor, etc.” As his opening chapter notes, the Yanomamö “are simultaneously peacemakers and valiant warriors.” Like all people, the Yanomamö have a deep repertoire of responses.

My conclusion is that Chagnon’s view of the Yanomamö is basically supported by the evidence. His data and interpretations are corroborated by many other anthropologists. Even at their “fiercest,” however, the Yanomamö are not so different from many other peoples around the globe. Yanomamö violence is certainly no more extreme than that of our Paleolithic ancestors, who appear to have brutally butchered one another with abandon. If recorded history is any measure of “fierceness,” the Yanomamö have got nothing on Western “civilization.”

Homo sapiens are the erotic-fierce people, making love and war too often for our own good. Fortunately, we now have the scientific tools to illuminate our true natures and to help us navigate the treacherous shoals of surviving the transition from a state society to whatever comes next.