Tuesday, September 24, 2013

The recurrent laryngeal nerve

I'm going to quote part of a Facebook exchange I ran across today:

Fulano De Tal 
RE The Recurring Laryngeal Nerve: The nerve's route would have been direct in the fish-like ancestors of modern tetrapods, traveling from the brain, past the heart, to the gills (as it does in modern fish). Over the course of evolution, as the neck extended and the heart became lower in the body, the laryngeal nerve was caught on the wrong side of the heart. Natural selection gradually lengthened the nerve by tiny increments to accommodate, resulting in the circuitous route now observed." - Richard Dawkins, The Greatest Show on Earth

i) It's striking how unbelievers make very confident pronouncements concerning things they know nothing about. At best, Fulano is relying on thirdhand information, and probably fourthhand information (or worse), on the laryngeal nerve. To begin with, his stated source of information is Dawkins. So that's secondhand. But Dawkins is no expert on giraffes. So, at the very least, Dawkins is relying on secondhand information about giraffes. Which would make it thirdhand info for Fulano. Moreover, I doubt Dawkins consulted an expert on giraffes. Rather, this example has become such a cliché in the evolutionary literature attacking ID theory that I expect Dawkins picked it up from another Darwinian science writer who's not an expert on giraffes. And where did that science writer get it?

ii) Moreover, Dawkins hasn't been a working scientist for decades. Why assume he even has an up-to-date knowledge of current evolutionary biology? When was the last time he published a scientific article in a peer-reviewed journal? 

iii) Furthermore, one of Dawkins' staple objections to ID theory is that theistic explanations are "science stoppers." 

Notice, though, that when he defaults to the inefficiency of the blind watchmaker to account for the recurrent laryngeal nerve, his explanation is a science stopper. Rather than investigating whether this has unsuspected engineering advantages, he just assumes it must be the clumsy byproduct of a mindless process. So he stops short. He contents himself with that superficial explanation, rather than conducting an in-depth cost/benefit analysis of the recurrent laryngeal nerve–in itself, in relation to the overall body-plan of a giraffe, in relation to the habitant of a giraffe, &c.  

Also observe that Dawkins simply propounds a just-so story to explain it. He doesn't provide any hard evidence. 

iv) Finally, that example has been contested. For instance:

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