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