Here is a depiction of the HMS Cambridge firing a torpedo (Illustrated London News, 1869):
And here’s my question: does the Cambrian explosion (the relatively sudden appearance of most phyla over a 10 million year period) torpedo evolution by random mutation and natural selection? Jerry Fodor and Massimo Piatelli-Palmarini, in their book, What Darwin Got Wrong (2010, pg. 52), think it might:
[M]orphological explosions may well reflect major changes in internal constraints as crucial components in speciation. If so, then the effects of natural selection may well consist largely of post-hoc fine-tuning in the distribution of subspecies and variants (Newman and Bhat, 2008): quite a different kind of account from the one of gradual selection of randomly differing small variations.
University of Chicago geneticist, Jerry Coyne, however, insists that, absent a miracle, the phyla in the Cambrian had to have simpler and common precursors that diversified, like everything else, via good old fashioned mutation and natural selection. The fossil record, being incomplete, is causing us to think in a confused way about this. He presents, as illustration of this confusion, an Intelligent Design argument (in which a phylum is likened to an automobile chassis), and smacks it down:
[T]he “top down” pattern is precisely what is expected if life resulted from a designing intelligence: humans, who are conscious designer[s], use a top-down strategy in their creations. Automobiles, for example, have retained the original design of an engine, four wheels, etc., while varying only in detail as time progressed.
This is a clever argument, but of course fails when we have a good fossil record, as in the evolution of mammals from reptiles or of amphibians from fish. We don’t see fully-evolved mammals appearing suddenly in the fossil record, later spinning off the various groups of modern mammals. Rather, we see a gradual divergence of mammal-like reptiles from reptile-like reptiles, with the major groups of mammals forming later.
In other words, Coyne is suggesting that what is true of classes (mammals and reptiles) surely is true also of phyla (like arthropods and chordates), and therefore the design argument must fail “when we have a good fossil record, . . .”
But that’s the problem, isn’t it? With regard to the Precambrian and Cambrian, it seems we don’t have a good fossil record. Or, rather, perhaps we do, and it’s just not matching our expectations of incremental increases in complexity and diversity via mutation and natural selection.
At the level of class, natural selection, as a chief mechanism of evolution, appears secure. But at the level of phyla, something seems curiously amiss. Like the historic disjunctures represented by the Big Bang and the appearances of life and mind in the universe, the Cambrian explosion seems to be a jump—a saltation, a French Revolution—that “changes everything.” When we talk, for example, about evo-devo, it is the basic body plans (arthropods, chordates, etc.) set in the Cambrian that are conserved. The on-off switching of the hox genes focus on the developmental timing and modular components overlaid upon the basic body plans. Thus, like the Big Bang and the origins of life and mind, the Cambrian explosion looms like an ontological mystery (a mystery of being): how did so much that is beautiful, complex, and essential to subsequent life arrive so suddenly, as if drawn from a magician’s hat?
It makes you want to speculate: are random mutations winnowed by natural selection really up to the task of accounting for the Cambrian explosion? I can’t help but wonder whether Simon Conway Morris is right: that at some level the basic body plans that we see and the consciousness that we experience are inevitable. Perhaps these disjunctive leaps occurred, not contingently, but because the dice are loaded: they are manifestations or arrivals of an eschaton (a divinely ordained historical climax that changes everything). It is mind-boggling, but maybe the universe’s original order is breaking its symmetry and entropically cascading through grand signposts (the Big Bang, the origin of life, the Cambrian explosion, human consciousness) on its way to still other world-shattering discontinuities—other, undreamed of by us, surprises.
Stuart Kauffman seems to think along the lines of the universe as a platform for emergent discontinuities. And, in religious terms, Christians famously await one of these discontinuities (the Second Coming). Rowan Williams, in conversation with Richard Dawkins, sees Jesus’s resurrection as an example of one of those moments in history where “there’s an opening in the world in which the underlying divine action comes through in a fresh way”:
Williams’s proposition of “divine action coming through in a fresh way” is not so much the direct intervention of God into the universe, tinkering with it (though, in crasser forms, it certainly could be). Rather, the proposition can be seen as imagining crucial moments in history (such a the Cambrian explosion) as a “put-up job,” a culmination of what was already, in embryo, present from the beginning (perhaps in the laws of physics and how they would make matter and energy cascade through time). The first miracle—and the only necessary miracle—is the ontological mystery (the mystery of information and being itself, the ground of being, the first order, the first symmetry) that is now entropically reverberating to its climaxes, its eschatons, its “second comings” and secondary explosions.
It is no surprise that early naturalists believed that animals were the product of celestial design, created by God to do their jobs.
Darwin dispelled this notion in the Origin.
Not so fast?