Unreal Nature

May 7, 2016

After the Fact

Filed under: Uncategorized — unrealnature @ 5:44 am

… “survival of the fittest” is a meaningless tautology because fitness is defined by survival, and the definition of natural selection reduces to an empty “survival of those who survive.”

Continuing through Wonderful Life: The Burgess Shale and the Nature of History by Stephen Jay Gould (1989):

… Our most precious hope for the history of life, a hope that we would relinquish with greatest reluctance, involves the concepts of progress and predictability. Since the human mind arose so late, and therefore threatens to demand interpretation as an accidental afterthought in a quirky evolutionary play, we are incited to dig in our heels all the harder and to postulate that all previous life followed a sensible order implying the eventual rise of consciousness.

[line break added] The greatest threat lies in a history of numerous possibilities, each sensible in itself after the fact, but each utterly unpredictable at the outset — and with only one (or a very few) roads leading to anything like our exalted state.

Burgess disparity and later decimation is a worst-case nightmare for this hope of inevitable order. If life started with a handful of simple models and then moved upward, any replay from the initial handful would follow the same basic course, however different the details. But if life started with all its models present, and constructed a later history from just a few survivors, then we face a disturbing possibility. Suppose that only a few will prevail, but all have an equal chance.

[line break added] The history of any surviving set is sensible, but each leads to a world thoroughly different from any other. If the human mind is a product of only one such set, then we may not be randomly evolved in the sense of coin flipping, but our origin is the product of massive historical contingency, and we would probably never arise again even if life’s tape could be replayed a thousand times.

But we can wake up from this nightmare — with a simple and obvious conventional argument. Granted, massive extinction occurred and only a few original designs survived. But we need not assume that the extinction was a crap shoot. Suppose that survivors prevailed for cause. [ … ] What does it matter if the early Cambrian threw up a hundred possibilities, or a thousand? If only half a dozen worked well enough to prevail in a tough world, then these six would form the rootstocks for all later life, no matter how many times we replayed the tape.

… Arguments that propose adaptive superiority as the basis for survival risk the classic error of circular reasoning. Survival is the phenomenon to be explained, not the proof, ipso facto, that those who survived were “better adapted” than those who died. This issue has been kicking around the courtyards of Darwinian theory for more than a century. It even has a name — the “tautology argument.”

[line break added] Critics claim that our motto “survival of the fittest” is a meaningless tautology because fitness is defined by survival, and the definition of natural selection reduces to an empty “survival of those who survive.”

… But if we face the Burgess fauna honestly, we must admit that we have no evidence whatsoever — not a shred — that losers in the great decimation were systematically inferior in adaptive design to those that survived. Anyone can invent a plausible story after the fact. For example, Anomalocaris, though the largest Cambrian predators, did not come up a winner.

[line break added] So I could argue that its unique nutcracker jaw, incapable of closing entirely, and probably working by constriction rather than tearing apart of prey, really wasn’t as adaptive as a more conventional jaw made of two pieces clamping together. Perhaps. But I must honestly face the counterfactual situation. Suppose that Anomalocaris had lived and flourished. Would I not then have been tempted to say, without any additional evidence, that Anomalocaris had survived because its unique jaw worked so well?

AnomalocarisDinoMcanb
Anomalocaris

My most recent previous post from Gould’s book is here.

-Julie

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