Fitter than thou

Fitness: the guaranteed derailer of any teaching situation regarding natural selection, and even of the larger topic, evolution.

Let’s dispose of the first nonsense first: “survival of the fittest.” In the first place it’s a stupid tautology; you’re fit because you survive / you survive because you’re fit. Even when you gesticulate and explain, it still doesn’t make sense … because no one survives, not individually nor as a species. This is about reproduction.

I’ll write about how the phrase worked its way into the 6th edition of The Origin of Species another time. The reason I’m not starting with it in detail is because it’s not effective pedagogy – at the outset students need concrete logic about biological causes, not gibble-gabble about dead Empire Brits’ opinions. I always get to that later, but later, if you see what I mean.

The definition fallacy: a quality you have or you don’t

Here I have to blame the role of the suffix, “-ness,” which is instantly read as a thing which one may or may not possess. It certainly suits the metal, epic fantasy, teenfic model concerning”the best,” “the most bad-ass,” “the chosen one,” and “the destined.” Dial down the mysticism to no-less dubious natural endowments, and you get “I can’t help being superior.” No wonder it’s constantly confounded with privilege and discrimination, which as an academic effect, yields a hostility from all extra-biological fields that is currently at a solid high.

I bobbled that final point a wee bit, but I hope the point comes clear:

  • In circumstances when an inheritable feature does consistently contribute to higher reproductive success (than those without it), then a given individual with that feature is by no means guaranteed such result.
  • In circumstances when that feature doesn’t so contribute, i.e., not consistently, then when a given individual with that feature does so benefit from it, there’s no selective result at a population level.

Therefore fitness can in no way be isolated into a given individual’s features as if it were a possession.

The meaning fallacy: what it accomplishes

Here I’m addressing the attractive but ultimately merely romantic inference that natural selection – especially in its mistaken synonymity with evolution – goes somewhere, gets somewhere, arrives, and makes a thing. In rebuttal, and harking back to Adapt this, remember that selection is subject to three meaningful stopping-points, none of which constitute an intrinsic relationship with external conditions.

I’ll peg this as the single most difficult error to dispel, because it shows up in various ways. The most popular is the humanocentric version, to assume the larger narrative of evolution is a study in human advancement and/or current status. You’ll usually find the embedded concept of moral purpose in there too. The primary forms include both the naturalistic fallacy of progressivism (from bestial ape to struggling bipolar man to socially-harmonious man to rarefied angel) and the infantile self-justification from the captains of industry slash imperials. Thomas Huxley eviscerated both in his brilliant Evolution and Ethics in 1893, and I submit that we need discuss them no further.

The unfortunate in-biology version of this fallacy was my topic in Against it, I say – the confusion between specialization and optimality. Here’s a neat example: the observation that deer go right ahead and eat birds’ eggs and nestlings when they find’em. I groan every time I see intellectual deficit about it in the scientific text of all places, e.g., invoking some “need for special nutrients pushing herbivores to eat meat.”

Poppycock. So-called “herbivory” is actually “ultra-omnivory,” physiologically speaking, because it expands the animal’s digestive range. By contract, the most extreme (obligate) carnivores are strikingly limited in their digestive capability, with the most extreme probably being sanguivory. A cow eats grass because it can in addition to everything else; a cat eats meat because it can’t eat anything else. All the flat grinding teeth and whatnot that we call “herbivorous specialization” don’t change that. A deer doesn’t eat the li’l baby bird because circumstances forced it, but because it found a yummy baby bird well within the range of its dietary processing capacity.

That’s important when it comes to the four questions I presented in Have you ever looked at your hands? – what is a given catch-phrase really saying, and for which question? Specifically evolution: that deer are “adapted for eating plants,” well yes, the digest-anything tract is necessarily found among the behaviorally/ecologically herbivorous creatures. However:

  • That doesn’t mean those two things are matched to one another (obviously they’re not), nor that the creature is locked down to that behavior (ditto).
  • It totally dodges the point of how it happened at all – don’t envision these animals choking down bushels of indigestible material and looking hungry and miserable until they “adapted” to solve that problem.

The success/survival fallacy: extinction

Briefly reprising the first video: reproductive success isn’t a priori possessed by an individual, but it occurs (or doesn’t) individual by individual. Certain circumstances may result in demographic, i.e. frequency-based change after a consistent effect on reproductive success through generations. None of this implies a specific effect on the size or fate of the population as a whole. It takes a lot of work to teach students that “reproductive success” is not the same thing as population growth, for instance.

The most extreme form of this fallacy is found in considering species survival in the context of ongoing extinctions to be “adaptation.” It’s arguably also the single most successful meme in evolution, or at least tied neck-and-neck with clinal improvement-by-anagenesis.

Maybe that needs a bit more clarification, that some species feature a reproductive profile which renders their offspring numerous and widely distributed – during a mass extinction (an incredible loss of species in a blip of geological time) this somewhat counteractss whatever is going on which has such a serious effect on all the species. It doesn’t mean you’re exempt from it, you just manage to outlast it longer than the other guys did.

Lions and tigers. Elephants. A smattering of great apes, merely one or two species per genus, including the loss of substantially more genera. Some “made it” through pure stochasticity, some through the countering effects of quickie reproductive details (in our case, perhaps our all-year reproductive season). But none of them through the details of whatever specializations that selection had produced, and consistently, a higher extinction rate in those groups featuring the most specializations, the lowest birth rates, and the most complex lives.

Just a hint for you – we may be the only remaining species of Homo because we were less specialized than our contemporaries during the Pleistocene. A bit less noble, eh?

Next: Who are you



4 thoughts on “Fitter than thou

    • The keys to making it through a mass extinction, given that the group you’re in is affected in the first place, seem to be:
      – abundance – if there are lots of you, it takes longer to wipe you out
      – replenishment – if lots are being born per unit time, ditto – but this is tricky because we’re talking about offspring who will themselves reproduce, so the “birth thousands, breed tens” of many creatures doesn’t count
      – generalist – wide range of diet including things you haven’t eaten before; wide range of tolerable tempieratures and light cycles

      None of these necessarily mean “boring,” but they don’t go well with being spectacularly big and full of interestingly-specialized anatomical devices. Nor with being endemic, meaning residing pretty much where you speciated and displaying the kind of ecological specialization which biologists label a “niche.”

      Compare the most prevalent modern forms of cows, pigs, dogs, and sheep, even without the population-boosting effect of domestication, to the diversity of their respective groups in the Pleistocene. You’ll find them to be very generalist. and anatomically a bit bland That’s us too.


  1. Hey Ron, I’m struggling through this stuff because it’s dense and not my field even remotely. Can you tell me if I’ve got this wrong? This is the way I often describe “descent with modification” to people, which frankly is no more controversial than fuckin’ mathematics.

    Imagine you’ve got a set of, oh, 100 items, colored red or green. Then what we’re gonna do is run it through time, from T=0 to T=much later. At all of those times, we take each item in turn. If the item is green, 40% of the time we’ll add another item of the same color to the set, and 60% we won’t. For the red items, the reverse. (You could modify this with more complicated rules for old age, bad luck, and so on, but let’s keep things simple.)

    By T=much later, there’s going to be an enormous population of red items relative to the green items. None of this is controversial in the least; a child could see it. Except if you call it “Theory of Evolution” or “Survival of the Fittest” or whatever-the-hell people get up in arms about. It’s not evolution “toward” anything, just dumb rules working themselves out over time, and the only concept of “fit” is that, under these unfair rules, red as a whole has a huge advantage: you’d *expect* it to dominate the population relative to green.

    I imagine you with a giant throbbing forehead vein right about now; your clenched hands about to break your laptop. As if speaking to a well-meaning child, what’s my little mathematical model got totally wrong?


    • I only hyperventilate over important stuff like realism in Marvel Comics. At this blog I’m mild and friendly.

      Your summary is wonderful with a couple of notes & nuances.

      First is the crucial specification of reproduction. Individual survival is irrelevant (to this process) except insofar as it facilitates reproductive events, and that is actually nowhere near as obvious or literal as one might expect. Survival is barely in the picture and ultimately, it isn’t at all. Or to turn the same thought around into a nice/happy version, one can live a long and lovely life with flatline real-outcome fitness.

      Second is what red and green really are. It’s easy to say “long teeth vs. flat teeth,” but the actual variables are developmental sequences with long unfamiliar names, and the degree to which those are inheritable. One cannot really get into how selection happens while black-boxing genes and development.

      Third is the context of other kinds of evolutionary change, in which this kind is embedded. Suffice to say there are lots of them, from large-scale effects like mass extinctions to small-population effects like genetic drift. Selection only works with what’s currently there, and these other effects are therefore incredibly important as its background.

      These points lay the foundation for encountering the much harder problem of cultural narratives and expectations. The trouble in explaining selection is not the thing in itself, but rather what the other person is 100% certain that you’re about to say as a moral-political directive. You could be up against the angry and fearful notion that you’re about to launch into a libertarian screed, or you could be up against the eager and agreeable search for confirmation that all religions are evil and especially Islam.

      Even if the expectations fall within the realm of biology, you are guaranteed to be up against the assumption that you are about to describe something cyclical and constructive, “so that” creatures avoid extinction, “so that” the camel got his hump, or “so that” a given ecosystem remains stable.

      Clearing all that out is dedicated education, the kind that requires the participant to pony up money and time.


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