According to the late Harvard University biologist Ernst W. Mayr, the greatest evolutionary theorist since Charles Darwin, “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.”

Reproductive isolation is the key to understanding how new species form, and many types of barriers can divide a population and split it into two different groups: geographic (such as a mountain range, desert, ocean or river), morphological (a change in coloration, body type or reproductive organs), behavioral (a change in breeding season, mating calls or courtship actions), and others. After isolation, if members of the split populations encounter one another and cannot produce viable offspring that can themselves later successfully interbreed and produce viable offspring (hybrids such as mules are infertile), then these two populations constitute two different species.

Let’s say that a species migrates out of Africa into Europe around 400,000 years ago and becomes reproductively isolated from its ancestral population for the next 320,000 years. It evolves distinctive anatomical features and adaptations for the colder climes. Moreover, even after other descendants of the original ancestral population move into Europe around 80,000 years ago, the skeletons from both groups show no obvious signs of blended characteristics. Modern scientists classify the creatures as two different species.

Then, however, genetic analysis reveals that members of these two species interbred and produced viable offspring that populated Europe and spread eastward as far as China and Papua New Guinea. By Mayr’s definition, these two interbreeding populations are not two species after all, but two sibling subspecies of the original African species. A subspecies has a characteristic appearance and geographic range, Mayr explains, yet he adds this significant qualifier: “It is a unit of convenience for the taxonomist, but not a unit of evolution.”

Thus it is — revealing the identity of my example — that we must reclassify Homo neanderthalensis as Homo sapiens neanderthalensis, a subspecies of Homo sapiens. A comprehensive and technically sophisticated study published in the May 7 issue of Science, “A Draft Sequence of the Neandertal Genome,” by Max Planck Institute evolutionary anthropologists Richard E. Green, Svante Pääbo and 54 of their colleagues, demonstrates that “between 1 and 4% of the genomes of people in Eurasia are derived from Neandertals” and that “Neandertals are on average closer to individuals in Eurasia than to individuals in Africa.” In fact, the authors note, “a striking observation is that Neandertals are as closely related to a Chinese and Papuan individual as to a French individual…. Thus, the gene flow between Neandertals and modern humans that we detect most likely occurred before the divergence of Europeans, East Asians, and Papuans.” In other words, our anatomically hirsute cousins are actually our genetic brothers.

This modified Out of Africa theory holds that around 400,000 years ago a population of hominids migrated northward through the Middle East and into Europe and parts of western Asia. Between 80,000 and 50,000 years ago another population from the ancestral continent journeyed a similar route into the Eurasian landmass, and there the two populations met and mated. We are their descendants. The Neandertal species did not go extinct, because it was never a separate species; instead population pockets of Neandertals died out around 30,000 years ago, whereas other Neandertal populations survived through interbreeding with their modern human brothers and sisters, who live on to this day.

I always suspected that Neandertals and anatomically modern humans interbred, based on a simple observation: humans are the most sexual of all the primates, willing and able to do it just about anywhere, anytime, with anyone (and even with other species if the Kinsey report is to be believed in its findings about farmhands and their animal charges). Given the viable hybrid offspring that the most diverse members of our species have produced as a result of cultural conjoinings through both ancient migrations and modern travel, one has to suspect that close encounters of the corporeal kind occurred not infrequently in those dark and lonely cave nights over the course of those long-gone millennia.

Now that is a tale worthy of a romantic novel, brought to you by science.

On July 2, 1866, Alfred Russel Wallace, the co-discoverer of natural selection, wrote to Charles Darwin to lament how he had been “so repeatedly struck by the utter inability of numbers of intelligent persons to see clearly or at all, the self acting & necessary effects of Nat Selection, that I am led to conclude that the term itself & your mode of illustrating it, however clear & beautiful to many of us are yet not the best adapted to impress it on the general naturalist public.” The source of the misunderstanding, Wallace continued, was the name itself, in that it implies “the constant watching of an intelligent ‘chooser’ like man’s selection to which you so often compare it,” and that “thought and direction are essential to the action of ‘Natural Selection.’” Wallace suggested redacting the term and adopting Herbert Spencer’s phrase “survival of the fittest.”

Unfortunately, that is what happened, and it led to two myths about evolution that persist today: that there is a prescient directionality to evolution and that survival depends entirely on cutthroat competitive fitness.

Contrary to the first myth, natural selection is a description of a process, not a force. No one is “selecting” organisms for survival in the benign sense of pigeon breeders selecting for desirable traits in show breeds or for extinction in the malignant sense of Nazis selecting prisoners at death camps. Natural selection is nonprescient — it cannot look forward to anticipate what changes are going to be needed for survival. When my daughter was young, I tried explaining evolution to her by using polar bears as an example of a “transitional species” between land mammals and marine mammals, but that was wrong. Polar bears are not “on their way” to becoming marine mammals. They are well adapted for their arctic environment.

Natural selection simply means that those individuals with variations better suited to their environment leave behind more offspring than individuals that are less well adapted. This outcome is known as “differential reproductive success.” It may be, as the second myth holds, that organisms that are bigger, stronger, faster and brutishly competitive will reproduce more successfully, but it is just as likely that organisms that are smaller, weaker, slower and socially cooperative will do so as well.

This second notion in particular makes evolution unpalatable for many people, because it covers the theory with a darkened patina reminiscent of Alfred, Lord Tennyson’s “nature, red in tooth and claw.” Thomas Henry Huxley, Darwin’s “bulldog” defender, promoted this “gladiatorial” view of life in a series of popular essays on nature “whereby the strongest, the swiftest, and the cunningest live to fight another day.” The myth persists. In his recent documentary film Expelled: No Intelligence Allowed, Ben Stein linked Darwinism to Communism, Fascism and the Holocaust. Former Enron CEO Jeff Skilling misread biologist Richard Dawkins’s book The Selfish Gene to mean that evolution is driven solely by ruthless competition, both between corporations and within Enron, leading to his infamous “rank and yank” employee evaluation system, which resulted in massive layoffs and competitive resentment.

This view of life need not have become the dominant one. In 1902 the Russian anarchist Petr Kropotkin published a rebuttal to Huxley and Spencer in his book Mutual Aid. Calling out Spencer by phrase, Kropotkin observed: “If we … ask Nature: ‘who are the fittest: those who are continually at war with each other, or those who support one another?’ we at once see that those animals which acquire habits of mutual aid are undoubtedly the fittest.” Since that time science has revealed that species practice both mutual struggle and mutual aid. Darwinism, properly understood, gives us a dual disposition of selfishness and selflessness, competitiveness and cooperativeness.

Darwin was born on February 12, 1809, the same day as Abraham Lincoln, who also struggled to reconcile our binary natures in his first inaugural address on the eve of the Civil War: “The mystic chords of memory, stretching from every battlefield and patriot grave to every living heart and hearthstone all over this broad land, will yet swell the chorus of the Union, when again touched, as surely they will be, by the better angels of our nature.”

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.

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Charles Darwin is back in the news, with Kansas school board members once again shifting seats Left and Right (with liberals this time winning out). Is there really a liberal-conservative split over the theory of evolution? There is. According to a 2005 Harris Poll, 63 percent of liberals but only 37 percent of conservatives believe that humans and apes have a common ancestry. Similarly, a 2005 Pew Research Center poll found that 60 percent of Republicans are creationists while only 11 percent accept evolution, compared to 29 percent of Democrats who are creationists and 44 percent who accept evolution.

These findings are unfortunate because if anyone should embrace the theory of evolution it is conservatives. Charles Darwin’s theory of natural selection is precisely parallel to Adam Smith’s theory of the invisible hand. Darwin showed how complex design and ecological balance were unintended consequences of individual competition among organisms. Smith showed how national wealth and social harmony were unintended consequences of individual competition among people. The natural economy mirrors the artificial economy. Conservatives embrace free market capitalism. In fact, we are against excessive top-down governmental regulation of the economy because we understand that it is a complex emergent property of bottom-up design in which individuals are pursuing their own self interest without awareness of the larger consequences of their actions.

The connection between natural selection and the invisible hand is most enlightening. Adam Smith was a professor of moral philosophy who posited a theory of human nature with competing motives: we are competitive and cooperative, altruistic and selfish. There are times of need when we can count on the humanity of strangers to help us, but daily trade in a marketplace is founded on the lesser angels of our natures, as Smith explained in The Wealth of Nations: “It is not from the benevolence of the butcher, the brewer, or the baker that we expect our dinner, but from their regard to their own interest. We address ourselves, not to their humanity but to their self-love, and never talk to them of our own necessities but of their advantages.”

By allowing individuals to follow their natural inclination to pursue their self-love, the country as a whole will prosper, almost as if the entire system were being directed by an invisible hand. It is here where we find the one and only use of the metaphor in The Wealth of Nations: “Every individual is continually exerting himself to find out the most advantageous employment for whatever capital he can command … He generally, indeed, neither intends to promote the public interest, nor knows how much he is promoting it. He intends only his own security; and by directing that industry in such a manner as its produce may be of the greatest value, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention.”

The connection between Smith and Darwin is through the British theologian William Paley, who in his 1802 book, Natural Theology, presented a theory of intelligent design and used Smith’s invisible hand metaphor. Paley discusses a breeding pair of sparrows who are unaware of the long-term and unintended consequences of their act of reproduction — the survival of the species: “When a male and female sparrow come together, they do not meet to confer upon the expediency of perpetuating their species … They follow their sensations.” God made sex fun because its end result — of which organisms are unaware — is beneficial to the population: “Those actions of animals which we refer to instinct, are not gone about with any view to their consequences … but are pursued for the sake of gratification alone.” Behind the scenes, Paley says, God is pulling the strings. How? “For my part, I never see a bird in that situation, but I recognize an invisible hand, detaining the contented prisoner from her fields and groves for a purpose, as the event proves, the most worthy of the sacrifice, the most important, the most beneficial.”

When Darwin was in college he read Smith’s Wealth of Nations and Paley’s Natural Theology. He consciously employed Smith’s invisible hand metaphor in the Origin of Species as a counter to Paley’s misuse of it. Here is Darwin’s description of what happens in nature when organisms pursue their self-love, with no cognizance of the unintended consequences of their behavior: “It may be said that natural selection is daily and hourly scrutinising, throughout the world, every variation, even the slightest; rejecting that which is bad, preserving and adding up all that is good; silently and insensibly working, whenever and wherever opportunity offers, at the improvement of each organic being in relation to its organic and inorganic conditions of life. We see nothing of these slow changes in progress, until the hand of time has marked the long lapses of ages, and then so imperfect is our view into long past geological ages, that we only see that the forms of life are now different from what they formerly were.”

So, where Adam Smith employed the metaphor of the invisible hand to describe a natural bottom-up process of self-organization, William Paley used it to describe a supernatural top-down process of divine organization. Charles Darwin’s theory of natural selection, then, is an inversion of Paley’s inversion of Smith’s metaphor. How recursive!

Today we know that the economy operates best without excessive top-down direction from governmental intelligent designers, and thus this is one among several reasons why conservatives should embrace Darwin and the theory of evolution.

This article was first published here.