You'll recall that Mr. Permavegan wrote to me seeking a "worthy opponent" to help him refine or dismiss his hypothesis that meat was a "fallback food of last resort" for our prehistoric ancestors. I boldly accepted the challenge...
...and then pulled a D.B. Cooper.
So, first, I offer my apologies to Jonathan, and to the rest of you, for this mean rock-tease. Though my disappearance was not intentional (in the sense that it was pre-meditated), its effect was the same regardless. I have no real defense, but a brief explanation may be in order: in short, I encountered serious time-management issues this semester, coupled with the grieving process over my Dad's death, both of which were stressful enough independently, but together were converging to be an emotional K-T Event for me. I decided, sometime in mid-January, that writing a regular blog was just too much on top of all this other stuff, and cynically deleted it, thinking it had done no good anyway.
But, I'm over that pity party now, rested, healthy again, and ready to maintain this blog in a more measured way than before (but that's for another post).
So, without further ado....
My critique of Maxson's hypothesis rests on three main points:
- He seems to misunderstand, and thus misapplies, the concept of a fallback food; in doing so, he concedes the argument to his oppoents (though apparently none of them were smart enough to notice!);
- He lacks precision when discussing our ancestry in the context of his argument (just like, it should be noted, most of his opponents); and,
- He engages in the naturalistic fallacy (again, just like his opponents).
What Is A Fallback Food?
Maxson argues that humans (by which I presume he means H. sapiens)
are not adapted to a structural dependence on meat. The evidence is much more compelling that we inherited an immunological resistance to meat-related pathogenecity that allowed us to survive on meat as a fallback food during times when superior plant-foods were not available.But, based on current understanding of human evolution, this formula is backwards. Meat would be what's called a "preferred food," and various plants would be "fallback food."
In anthropology, fallback foods are resources upon which primates depend for survival during times when preferred foods are scarce. Preferred foods are "high-quality" (that is, nutrient-dense) resources for which primates will temporarily abandon their fallback strategy when the opportunity presents itself, and for which they will take risks.
It might seem that preferred foods are more evolutionarily significant, given their caloric pay-off, but they're not. Because fallback foods are what a given primate population eats most of the time, they influence that population's evolutionary development far more than preferred foods do. As Marshall, et. al., (2009) summarized it:
Fallback foods are becoming increasingly invoked as key selective forces that determine masticatory and digestive anatomy, influence grouping and ranging behavior, and underlie fundamental evolutionary processes such as speciation, extinction, and adaptation.Maxson is basically right that humans (H. sapiens?) have inherited a suite of characters developed over 70 million years of primate evolution, and that the primate adaptation to frugivory is the foundation of our anatomy and biology. But this doesn't mean that fruits, tubers and seeds were our preferred foods; quite the opposite, in fact. They were what "we" depended on most of the time for our daily survival, and thus they became the selective factors with the greatest influence on our dental and digestive anatomy.
By arguing that meat was a "fallback food of last resort" for our ancestors, Maxson is essentially saying that meat-eating made us human by shaping our anatomy in a unique way... precisely what his "livestock propagandist" opponents appear to be saying, too! I doubt this was his intention, however; he wants to argue that meat-eating wasn't terribly important to our evolution, and he'd be on much better footing if he reversed his categories and called meat a risky, preferred food... which is what most anthropologists think it was, anyway.
(It hasn't been lost on me -- nor should it be on you -- that none of Maxson's opponents appear to have called him to the mat on this point! More evidence that "paleo-dieters"/"livestock propagandists" know much less about evolution than they think they do!)
Who Is This "We"?
In a significant portion of his essay, Maxson refers to human ancestors and modern humans alike under the umbrella pronoun "we." While from an animal-rights perspective I applaud his inclusiveness, I'm afraid it's not precise enough for the purposes to which he wants to put it. When talking about what "we" are or are not adapted for, or what "our ancestors" evolved to do, one cannot simply speak so vaguely.
Which human species are Maxson referring to? The australopithecines? The paranthropus? H. heidelbergensis, believed to be the common ancestor of both our species and H. neanderthalensis?
It matters, because hominin species have developed in a wide range of habitats and climatic conditions across a large slice of geologic time, and have exploited a varied range of fallback food and preferred food strategies. If we aim to figure out precisely how important meat-eating was to the evolution of modern human anatomy, we have to speak with more precision. Specificity brings clarity, especially in scientific discussions.
There is a broad tendency for people to talk about all of these human species as though they are all equally relevant to the evolution of H. sapiens. Vegans and carnists alike are equally guilty on this score, each camp cherry-picking the traits or species that seem most suitable to their respective bias, often with little regard for the actual patterns and context of the fossil record.
Vegans, for instance, will highlight the apparent dependence of (some) australopithecines on roots and tubers that grew on Pleistocene savannahs, ignoring everything that happened in the following 2 million years.
Likewise, carnists will invoke, say, the heavy meat-dependence of H. neanderthalensis, with no regard to the fact that Neanderthals are not our ancestors. Or, they will point to chimpanzees hunting and killing small game, without explaining how such behavior has shaped chimp (let alone human) evolution.
This is insufficient in both cases, at least if our goal is to inform the debate with actual science.
Who Cares What Species X Ate?
Finally, Maxson seeks to argue that "a plant-based diet is most definitely the natural diet of Homo sapiens." I'm glad he didn't write, "veganism is most definitely the natural diet of Homo sapiens," because while the first statement might approach plausibility, the second one is flatly absurd.
Yes, you read that right. A vegan just wrote that veganism is not the natural human diet. And he'll now write that the "paleo-diet" isn't, either.
As a scientist(-in-training), I am skeptical that there is any such thing as a "natural human diet." True, our species possesses a suite of characters inherited from (largely) frugivorous primate ancestors. It's true, also, that our species has for its entire history hunted and killed other animals for food. Neither of these facts, however, (nor any of the many others that each "side" in this debate can muster) implies something about what's "natural" for us to eat.
I realize that Maxson hasn't forthrightly stated that veganism is our natural diet, but his whole argument seems to rest on that implication. As does, it should be noted again, the bulk of his opponents' arguments with regard to their particular diet ideology (i.e., "paleo"-dieters argue we should eat animals because our ancestors did).
The problem is that both lines of argument rest on the naturalistic fallacy. From the ethical perspective of modern humans in modern situations, what our prehistoric ancestors did is irrelevant. So what if australopithecines were mostly herbivorous? So what if Cro-Magnons hunted and ate bison? We are not living in their world or facing their challenges.
From a biological perspective, it's certainly true that humans have a fundamental need for specific nutrients. But that by itself doesn't mean we have a need for (let alone an obligation, either biological or ethical, to eat) specific nutrient sources. Neither meat nor vegetables possess magic powers, and we have come far enough technologically to make the question moot, anyway. There are supplements for everything.
Further, it's a mistake to assume (as both camps here often do) that because we have such a biological need, that need was somehow being met in our ancestors' daily diets. It's entirely likely that our ancestor species, like most others, passed on their genes by living just long enough to ensure their offspring survived to sexual maturity. That's good enough, as far as evolution is concerned. Natural selection doesn't care if you've met all your daily nutritional requirements; it just needs you to make sure your kids live long enough to fuck.
I'm dubious about all arguments from an appeal to nature, whether from vegans or carnists. Among vegans, it often seems to signal a reluctance to face the facts about our species. It's as though they think accepting H. sapiens' meat-eating and hunting past somehow weakens the moral argument for animal rights. I don't think it does, any more than the long history of human slavery weakens the moral argument against servitude. One does not need to deny the historical reality of slavery to argue that slavery is wrong. Same thing applies to animal-eating.
Veganism is an entirely modern philosophy, and there is nothing to wrong with that. Attempts to reverse-engineer it into our history and our evolution are doomed to failure, and only weaken our case in the long run when properly-skeptical listeners check our factual claims and find them wanting.
Vegans should, in my opinion, always engage non-vegans on moral and ethical grounds first, only resorting to "health" arguments when they're actually on our side.
Of course, the natural sciences can inform our ethics, but we should all have learned by now that biology is not destiny. Vegans argue that humans descend from a long, herbivorous ancestry, and that many of the traits of that ancestry are reflected in our anatomy. Carnists retort that cavemen met many of their nutritional needs by eating meat, and that meat-eating might have shaped some aspects of our physical evolution.
You know what? They're both right. Personally, I think neither side will ever win the debate over H. sapiens' "natural" diet, because no such thing exists. We might as well, someone once said, debate how many angels can dance on the head of a pin.
And from an animal-rights perspective (the basis of my personal commitment to veganism), it's a pointless argument, anyway. The primary goal of the vegan movement is -- or ought to be -- saving nonhuman animals from exploitation. I don't see how trying to prove veganism is "natural" helps that goal.