Convergence part 5: an embarrassment of riches


In parts onetwo, and three of this series, I showed that some intelligent design proponents have created an alternate history of biological thought, in which evolutionary biologists have only recently discovered that similar traits often appear in distantly related species. I showed that this picture is false, and I gave a sampling of quotes–from Jean-Baptiste Lamarck, Charles Darwin, Ernst Mayr, George Gaylord Simpson, Willi Hennig, and others–demonstrating that evolutionary biologists have recognized that this phenomenon is common for as long as there can reasonably be said to have been evolutionary biologists. In part four I explained why widespread convergence is not evidence against common descent, as some ID proponents have claimed.

Mivart Cover

Now I’ve come across a contemporary of Darwin who wrote about widespread convergence. English biologist St. George Jackson Mivart was a critic of Darwin’s theory, and his 1871 book On the Genesis of Species argues against the sufficiency of natural selection to explain the evolution of complex structures. Darwin devoted considerable space in the Sixth Edition of the Origin to responding to Mivart’s objections (pages 176-203).

In Chapter 3 of On the Genesis of Species, entitled “The co-existence of closely similar structures of diverse origin,” Mivart contends that

…by “the action of Natural Selection” only it is so improbable as to be practically impossible for two exactly similar structures to have ever been independently developed. –p. 74-75

In this chapter, he argues that

So great, however, is the number of similar, but apparently independent, structures, that we suffer from an embarras de richesses. –p. 92

and

Many cases have been adduced of striking likenesses between different animals, not due to inheritance. –p. 105

and concludes

In this third chapter an effort has been made to show that while on the Darwinian theory concordant variations are extremely improbable, yet Nature presents us with abundant examples of such; the most striking of which are, perhaps, the higher organs of sense. –p. 108

Mivart was an evolutionary biologist (he was also a theist); he wasn’t arguing against common descent, only that something more than natural selection, some “innate force”, was needed to explain at least some examples of evolutionary change. My purpose here is only to show, once again, that the revisionist history suggested by some intelligent design proponents is false.

Evolutionary biologists have known about, and written about, convergent evolution for as long as there have been evolutionary biologists. Mivart devoted a whole chapter to convergence in 1871, and Darwin spent nearly thirty pages responding to his objections in the sixth edition of the Origin. Suggestions by Günter Bechly, Granville Sewell, Lee M. Spetner, and others that evolutionary biologists have only recently recognized that convergence is widespread, or even that it is “invented” as a post-hoc rationalization to dismiss evidence against common descent, are either bad scholarship or lies.

 

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