George Orwell would have loved this: an immodest proposal that humans are hybrids . . . of chimpanzees and pigs. (Let’s be charitable and take “chimpanzees” as shorthand for “an apelike common ancestor of chimps and humans.”)
No, it’s not a joke, though you might at first mistake it for Orwellian or Swiftian satire. Nor is it just an isolated, fantastic assertion. It’s built on a thoroughly researched and carefully argued, if far-fetched, alternative theory of the origin of new species, in which hybridization plays a significant part and is claimed to be more common and more possible across wider taxonomic gaps, with only partial loss of fertility, than commonly thought. (The uniquely dysfunction-riddled quality of human sperm is offered as one piece of evidence.) The theory’s progenitor, geneticist Eugene M. McCarthy, is a “saltationist” (from the Latin for “leap”)—a proponent of the concept of sudden, major evolutionary change—and he annotates his theory with a history of the argument between saltationists and gradualists, claiming that Darwin was and became more of a saltationist behind the scenes than he let on in the Origin.
The argument is long and complex and, frankly, I haven’t gotten very far into it yet. And I may yet be persuaded (comments are open—have at it!) that it is too crackpot to be worth the time. Suffice it to say that the argument about pigs is supported by a long list of features we have in common with pigs but not with any primate—among them a prominent, cartilaginous nose, naked skin with a thick layer of subcutaneous fat, multipyramidal kidneys, and “glabrous mucous membrane bordering lips.” But note that when it comes to skin, at least, lean, hairy wild pigs don’t have these characteristics, so you might as plausibly argue that a human mated with a wild pig to produce the domestic pig—thus creating dinner in our own image.
(Our noses, naked skins, and subcutaneous fat are at least as well accounted for by Welsh feminist Elaine Morgan’s aquatic ape theory. I’ve long been fond of this one, which receives support from every trip to the beach or the pool where you see that beatific, homecoming smile on faces of all ages. That link is a very entertaining video of Morgan challenging evolutionary dogma—”Charles Darwin must be spinning in his grave!”—but if you’re like me and don’t have time for a video, here’s a written summary.)
So why is this weirdness worth posting about? Because challenges to evolutionary dogma, which are increasing in number and coming from increasingly respectable scientific quarters, are a symptom that the theory as it stands is too stiff and tight to contain the facts we are discovering and is about to split like a chrysalis (even if “about to,” in mental geological time, is measured in decades). Two examples are the exploding field of epigenetics, which raises the possibility that mutation could be creatively responsive to rapid environmental change, and eminent mathematician Leslie Valiant’s provocative book Probably Approximately Correct, which I capsule-reviewed here. The review was unkindly cut, and it’s short, so here’s the original:
A winner of the Turing Award, a.k.a. the “Nobel of computing,” Leslie Valiant celebrates Alan Turing as the progenitor of a third scientific revolution, potentially as profound as Newton’s and Einstein’s in transforming our understanding of the world. Why not “fourth revolution”—why omit Darwin? Because—it’s the bombshell of this slim, math-heavy book—Valiant dares to say Darwin’s theory is radically incomplete, that until it is equipped to make quantitative, verifiable predictions, evolution by natural selection cannot account for the complexity of living things and is not “more than a metaphor.” That amounts to saying the emperor is naked, but Valiant offers no drop of succor to creationists. Rather, he seeks to arm neo-Darwinian theory against their onslaughts by elucidating the mechanistic, quantitative basis it must have in a world “without a designer.” The algorithms of computational learning theory, he posits, will be key—a special kind he calls “ecorithms,” that incorporate information gathered from the environment to improve an organism’s “performance.” Nature and nurture—evolution, civilization, and individual experience—thus form one continuous learning curve, and Turing’s heirs have only just begun to plot its equation.
These challenges invite thinking outside the box, sketching out novel pathways for investigation—like the first strands of spider’s silk flung into the void—many of which will prove dead ends, but a few of which may take hold and begin to thicken and glisten with evidence, revealing a new pattern that reorganizes all that was known and thought before. McCarthy writes of an “unknown force” that some nineteenth-century biologists sensed at work in evolution. This sounds like a hidden religious agenda; probably in the nineteenth century it sometimes was, and I can’t yet tell whether McCarthy has such an agenda or not. But taken straight, those words reveal a refreshing humility: much about what we life forms (“all my relatives”) are, and how we got here, is in fact unknown. My own sense is that what science itself is discovering is fixin’ to blow both conventional science and conventional religion out of the water.
I’ll leave you with two nineteenth-century quotes from McCarthy’s website, macroevolution.net:
Every great truth begins as heresy and ends as superstition. —T.H. Huxley
There may be an unknown factor that will cause quite as great a surprise as Darwin’s.
—Henry Fairfield Osborn