More about how evolution works: multicellularity (Evolution)

by David Turell , Thursday, November 03, 2016, 00:15 (2941 days ago) @ David Turell

Massimo Pigliucci takes on Wagner and disagrees with his Platonic approach:

http://nautil.us/blog/the-neo_platonic-argument-for-evolution-couldnt-be-more-wrong

"Just read the last two sentences of his 2014 book, Arrival of the Fittest: How Nature Innovates. They come in an epilogue, titled “Plato’s Cave.” “We are shedding new light on one of the most durable and fascinating subjects in all of philosophy,” he writes. “And we learn that life’s creativity draws from a source that is older than life, and perhaps older than time.” (Italics mine.) The source of this creativity, Wagner argues, is “nature’s libraries.” It’s a metaphor for an abstract storehouse of information that we can never physically encounter. “These libraries and texts,” he writes, “are concepts, mathematical concepts, touchable only by the mind’s eye.” This is Platonism. Are conceptual truths discovered, or invented? Platonists believe the former, and “Platonism,” Wagner writes, “has the upper hand in this debate.”

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"Wagner begins to veer off the main course of modern biology when he talks about the “essence” of species, which he links directly to Platonism: “A systematist’s task”—of organizing biological forms in nested, highly branching trees, or clades—“might be daunting, but it becomes manageable if each species is distinguished by its own Platonic essence,” he writes. “For example, a legless body and flexible jaws might be part of a snake’s essence, different from that of other reptiles. Indeed, the essence really is the species in the world of Platonists. To be a snake is nothing other than to be an instance of the form of the snake.”

"No, definitely not. Modern biology has long since rejected any talk of “essence.” Indeed, Darwin was what we might call a species anti-realist: He thought species are arbitrary boundaries drawn by humans for their own convenience, not reflective of any deeper metaphysical reality. Second, no, snakes cannot reasonably be thought of as “nothing other than an instance of the Form of the snake.” Not only is that idea scientifically inert (how do we study these Forms? Where are they?), it is also a way of seeing things that is in serious tension with the whole concept of evolution.

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"Who knows what future evolution has in store for the descendants of today’s snakes. To say that what we see now somehow represents the Platonic terminus of an evolutionary process is entirely groundless.

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" Wagner insists that Plato will have the last word—we just need to dig deeper. He quotes the 1905 biologist Hugo De Vries, one of the re-discoverers of the work of Mendel, who established genetics and was skeptical of Darwin. De Vries famously said: “Natural selection can explain the survival of the fittest, but it cannot explain the arrival of the fittest.”

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"The question Wagner believes he’s answered is: “Since mutation is random, how does natural selection ‘know’ how to find its way in the very, very large library of possible forms?” As he says: “Without these pathways of synonymous texts, these sets of genes that express precisely the same function in ever-shifting sequences of letters, it would not be possible to keep finding new innovations via random mutation. Evolution would not work.”

"Yes it would! Natural selection does the work of “walking” a population through the library, and it is the combination of a random process (mutation) and a non-random one (selection) that yields evolutionary change. But the library doesn’t exist before natural selection “walks” through it. The analogy is misleading: It is better to think of a library that is created (and partially destroyed) moment by moment as life evolves. There is no mystery here, and there hasn’t been for about a century. Thinking in terms of libraries and Platonic Forms is simply not helpful to the biologist. (my bold)

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"What does it mean for an abstract concept, or a possibility, to “exist”? These are the very same questions faced by mathematical Platonists, and biological Platonism—like its mathematical counterpart—simply seems to conjure up a problem where none existed before.

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"In philosophy of science, we like to keep metaphysics to the necessary minimum, and Platonism simply multiplies ontologies gratuitously, without any payback in either philosophy or science."

Comment: Wagner may well by off on a wild tear, but Pigliucci's reliance on the power of natural selection is also off the rails. Natural selections sits passively waiting for innovation. We still don't know how that happens, or why it happens, if there is no need for innovation as in the jump from bacteria to multicellularity.