Paleolithic Fantasies


We live in an age like all previous ages, one in which thinking people assess the state of the world, find it wanting, and consequently seek a better, even perfect, way of life. Such people tend to roughly divide into those who seek their utopias in a vision of the future (today: think digital prophets, genetically modified crops) or a return to a golden past when human beings were in perfect harmony with nature (past: think Eden and the Noble Savage; today: think organic farming, artisanal cheese). Interestingly, one finds both types among both liberals and conservatives, though usually with different emphases (liberals tend to go for the organic, conservatives for traditional morality, while both seem to think that digital technology holds great promise for the future, either through greater community or better security). And advocates of both sides seem to appeal, either implicitly or explicitly, to “human nature” as the ultimate measure of the perfect way of life (using either Darwin or the Bible as the validating text). Thus, amid all the changes of outward circumstance, human nature has remained unchanged through time.

Marlene Zuk, author of Paleofantasy: What Evolution Really Tells Us about Sex, Diet, and How We Live (W. W. Norton, 2013), addresses the myth, the just-so story, of a fixed human nature from an evolutionary perspective. An evolutionary biologist currently associated with the University of Minnesota, Zuk has conducted extensive field research, particularly on crickets, and is the author of numerous specialized articles and several popular books on evolutionary biology, behavioral biology, and sexual selection. She is therefore particularly well-qualified to demolish popular myths about human evolution, which she does with clarity and wit in this new book. (Her wit is best illustrated by her statement that “After all, nothing says evolution like a brisk round of the plague.”) Her immediate targets here are evo-myths about diet and health, particularly those that base their tenets on the very false idea that contemporary human beings are Paleolithic creatures uncomfortably and unhealthily stuck in an unnatural modern industrial environment. In other words, the natural man, the Noble Savage, the Eden which we have lost, is to be found in the lifestyles of early Stone Age humans prior to the development of agriculture (the true Original Sin) and settled life, that is prior to about 10,000 years ago. Supposedly, humans of the Paleolithic lived in that much admired perfect harmony with nature, and to restore our health and souls, we need to retrieve that lifestyle and apply it to our urbanized lives today.

Alas, like all utopian dreams, whether of past or future, what Zuk calls paleofantasies are exactly that, fantasies, and in the course of demonstrating just how fantastic they are, she treats her readers to a particularly clear and nonidealogical series of lessons on what evolution really is. And what it is not: it is not purposeful and it is not perfect or ever perfected. Thus, she demolishes the notion of the Noble Savage (by whatever name) when she writes that there is no utopian moment of perfect synchronicity between human beings and their environment. Both organisms and environments constantly change (and both humans and environments certainly did over the 2.6 million years of the Paleolithic period), and to think that today’s human beings are unchanged from those of even a mere 10,000 years ago “misses the real lessons of evolution” and “is specious” (p. 59). And lest we think that evolutionary change moves in some kind of logical direction, she writes that “evolution is more of a drunkard’s walk than a purposeful path” (p. 78).

Evolution never intends anything. It is a Rube Goldberg contraption, or rather the creatures it throws up are, because, rather than aiming at or achieving perfection, it measures success only by reproductive success. “If something works well enough for the moment, at least long enough for its bearer to reproduce, that’s enough for evolution” (p. 8). When you think about it, this is actually an excellent measure, simply because “perfection” is purely a human concept, and no one can agree on just exactly what perfection is. Should we eat only meat, because, as some paleo diet buffs claim, that’s what our Pleistocene ancestors ate? Or should we eat only raw vegetables and fruit, because, as other buffs claim, those were the exclusive menu items of our ideal past? Should we eschew grains, because they are cultivated and therefore not natural? Just exactly what would the “perfect” diet for human beings consist of?

According to Zuk, it depends. As she shows, various populations of human beings have evolved to utilize foods that our hunter-gatherer ancestors would not have been able to eat. For example, adults of some populations can digest milk, while the majority of human adults cannot (lactose intolerance). Certainly, the latter should avoid dairy, but the former can consume dairy products pretty much as they please. Insofar as the deleterious effects of agriculture are concerned, yes, it appears to be true that initially human health and well-being declined after people began cultivating grain crops and living in permanent settlements, but Zuk points out that it did not take all that long for this disadvantage to disappear; and as we know, agricultural societies grew larger and faster than foraging societies (reproductive success again being the measure of evolutionary success). Certainly some kind of genetic mutations could have occurred that conferred a greater ability to prosper on a diet high in grains; but it is also possible that as people improved their knowledge of cultivation and selectively improved the quality of their crops, and also exploited the advantages of settlements in facilitating trade, they overcame the initial disadvantages of agriculture. But whatever the case, it’s important to keep in mind that the early agricultural peoples themselves apparently thought that the advantages of agriculture outweighed its disadvantages—why else persist in farming?

An analogous point could be made about our modernity: If modern urban life is so bad for us, so unnatural and maladaptive, why did we develop it in the first place? If we are really, as some do argue, merely products of biological evolution like any other animal and, as some do argue, our consciousness is merely an illusion, how did we “evolve” a state of affairs so contrary to our biological being? And why do we cling to it so tenaciously? If it were really so horrible, wouldn’t we be fleeing the city for the more natural environments of the northern woods or western prairies (the United States’ closest approximation of the Edenic savannahs)? The fact that we do not suggests that urban industrialized life may not be so bad for humans after all. (How bad it may be for other organisms is a different question.)

Whatever the sources of some people’s dissatisfaction with modern human life, a mismatch between our Paleolithic natures and modernity is not one of them, and the appeal to evolution is, as already noted, based on a misconception of what evolution is. A major aspect of that misconception is an over-emphasis on natural selection. But as Zuk points out, “it is important to distinguish between two concepts that are sometimes—incorrectly—used interchangeably, evolution and natural selection. At its core, evolution simply means a change in the frequency of a particular gene or genes in a population” (p. 251). The mechanisms by which these gene frequency changes occur include not only natural selection, but genetic drift, gene flow, and mutation. “Genetic drift is the alteration of gene frequencies through chance events” (p. 251). “Gene flow is simply the movement of individuals and their genes from place to place, and activity that can itself alter gene frequencies and drive evolution” (p. 252). “The final way that evolution sans natural selection can occur is via those mutations, changes in genes that are the result of environmental or internal hiccups that are then passed on to offspring” (p. 252). In order to see whether or not evolution is occurring in humans today, one does not look at superficially visible traits but at changes in gene frequency among human populations.

Another all too common misconception is that “evolution is progressing to a goal” (p. 252), what can be called the teleological error. Even well-known and well-informed people believe that evolution is goal directed. For example, Michael Shermer, the editor of The Skeptic magazine and the author of a number of pro-evolution books, writes in The Science of Good and Evil that “Evolutionary biologists are also interested in ultimate causes—the final cause (in an Aristotelian sense) or end purpose (in a teleological sense) of a structure or behavior” (p. 8); he then states that “natural selection is the primary driving force of evolution” (p. 9). In contrast, Zuk reiterates throughout her book that “everything about evolution is unintentional” (p. 223), that “all of evolution’s consequences are unintended, and there never are any maps” designating a foreordained destination—and she is in fact an evolutionary biologist!

A good example of an unintentional evolutionary consequence is resistance to HIV, the retrovirus that causes AIDS. As it happens, some individuals are resistant or immune to the retrovirus, but not because evolution or natural selection intended them to be so. Centuries ago, bubonic plague swept through Europe; millions died of this highly infectious disease, but some few people did not get the disease despite having been exposed to it. No doubt they thought God had spared them for some divine reason. Centuries later, some of their descendents were exposed to HIV and did not become ill. Did God plan that far ahead to spare these few lucky individuals? Did evolution? No. A random mutation happened to render human cells unreadable to the plague bacterium (or, as Zuk suggests is more likely, unreadable to the smallpox virus); consequently, the bacteria could not enter the cells and wreak their havoc. The mutation would have had to have occurred before the introduction of the disease into the lucky few’s environment (there would not have been enough time for it to occur and proliferate after the disease’s introduction), and may have had no prior function, good or bad. As chance would have it, centuries later, the same mutation also made the owner’s cells unreadable to the AIDS virus, thus rendering him or her immune to HIV—quite by chance. Pace Lamarck, perhaps we can say that it is not characteristics that are acquired, but functions. The gene mutation that confers HIV immunity has after many generations finally an acquired function.

Why then do organisms seem so perfectly adapted to their environments? Perhaps they are not so perfectly adapted as they appear to human eyes; more importantly, since environments change, organisms must change as well, but perhaps if they were too perfectly adapted (each and every individual of the species therefore being identical), they would rather quickly become imperfectly adapted to even small changes in their environment. Perhaps, then, perfection is an extinction trap rather than a desirable goal.

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