Comment: From the Armchair to the Toilet: McGinn’s Evolutionary Tale of Disgust

One of Strohminger’s (2014) central criticisms of McGinn’s (2011) theory of disgust is his negligence in failing to consult science, or even common sense. I will deepen both of these criticisms via a closer examination of McGinn’s theory of the function and evolution of disgust. While it lies in the background of much of what he says, McGinn does not devote a great deal of attention to his evolutionary account. The majority of the discussion comes in Chapter 6, “The Function of Disgust.” Having earlier denied disgust to animals (a mistake that Strohminger has already addressed), McGinn focuses on what it is about the human condition that required that we alone evolved disgust. He says this difference lies in the vastly expanded scope of human desires. This expansion allegedly occurred during a hypothetical and hitherto unrecognized epoch in human evolution, which I will call the Caligulocene. The Caligulocene followed the biological evolution of uniquely human cognitive capacities (such as imagination and intellect, and our sense of the future, possibility, and mortality), and these cognitive capacities had the maladaptive side effect that humans underwent an unrestricted expansion of their desires.

For example, he says, because we could conceive of the future, we were anxious about whether there would be food tomorrow, so we consumed as much of it as possible. Perhaps we will have no mating opportunities in the future, so better to have as much sex as possible. More expansively, humans were not limited to thoughts of the finite, and as such we were able to conceive of a potentially infinite number of objects of desire. Consequently, no finite number of desired objects could suffice—human desires became “essentially infinite, unquenchable” (2011, p. 124). During the Caligulocene, the only force between early humans and complete decadent collapse was our willpower, but willpower alone could not suffice, so disgust arose as a Leviathan to reign in “a prior tendency in our make-up, namely, boundless excess.” “In the simplest case,” he says, “disgust exists not to prevent us from eating poisonous food, but to prevent us from eating too much good food,” and “the original disgust objects (according to this hypothesis) were objects that we were unhealthily greedy about” (2011, p. 125).

Aside from the vast amount of evidence that disgust does function to prevent us from ingesting pathogens, this account is in clear conflict with current (and vastly more plausible) “evolutionary mismatch” explanations of such excesses of food and sex (e.g., Power & Schulkin, 2013), which McGinn (2011) does not mention here. Briefly, mismatch theories hold that early humans, like all of their evolutionary ancestors, lived in an environment where food and mating opportunities were limited. Under such conditions, it was on balance adaptive to, for example, eat as much as possible. This theory holds that our current severe problems with these excesses have more to do with recent cultural innovations (resulting in a surplus supply of these previously desired things), than with any cognitively expanded desire to, for example, eat more and more kinds of doughnuts.

In any case, while the basic fact that disgust protects from the excesses of normal appetites is true enough, the desires of Homo Caligulus do not stop with these. Here, McGinn says, we have to think our way back into prehistory, and “we must be prepared to be bold” (2011, p. 127). Essentially, when the ordinary objects of our desire ran short, or when we grew tired of them, our desires began to spill over, leading us to have sex with unorthodox objects, and to eat anything that seemed edible. I could not see it coming, but McGinn says, “You can see where I am going with this: early humans started desiring sex with dead bodies and wanting to eat feces … maybe also desiring to eat decayed human flesh” (2011, p. 127). Such desires, he says, naturally escalate into the strongest temptations, such as incestuous necrophilia. Really.

Taking all of this perhaps more seriously than it deserves, what is (or could be) the evidence for this story? McGinn (2011) gives plenty of examples of depraved human behavior, indiscriminately mixing together various periods of human history, with a stronger emphasis on the present. Granted, there is no shortage of examples that our higher cognitive capacities can lead us into all manner of bizarre behaviors, but the question is not whether people do sometimes do these things, but rather whether the desire to do so is (or was), universal and intense, and McGinn’s examples provide no evidence to support this more general hypothesis.

If we turn to standard anthropological methods for evidence (which is more than McGinn does), the situation does not improve. Is there genetic or morphological evidence for massively increased inbreeding during the onset of our cognitive explosion? Do we see a vastly increasing number of human bones with human tooth or tool marks on them at early hominid campsites? Feces on cooking utensils? Artwork depicting these desires? Corpses (perhaps infants) increasingly posed in sexually provocative ways in their burial sites? Not that I know of. Traditional societies are also often studied as more closely exemplifying our ancestral condition, but is there evidence for the widespread (or at least much more frequent) occurrence of coprophagia, necrophilia, or incest among them? While there are cultural differences in these respects, nowhere do we find behavior widespread or extreme enough to be consistent with the hypothesized pressures of the Caligulocene, and nowhere does McGinn attempt to provide substantial, empirical evidence for it.

This inventory is far from a comprehensive account of the flaws of McGinn’s theory. Nevertheless, I hope it suffices to explain why, in the end, I am (truly) in doubt as to whether we are meant to take any of this seriously—whether McGinn’s evolutionary story is not merely a joke, but intended as such. Either way it’s not that funny.