Sea Turtles and Intelligent Design

Charlotte skyline from Marshall Park (credit: James Willamor)

I recently gave a talk about the illusion of God’s presence in my old stomping grounds, Charlotte, North Carolina. I was in town for other reasons, but I asked the Charlotte Atheists and Agnostics if they would like me to speak to their group, and they kindly said yes. A good friend from high school was in the audience, and he asked a question that I could not completely answer in the time we had for discussion and book signings. Fred had been reading the book in the days before the talk, and his question concerned my discussion, in chapter 4, of the amazing behavior of sea turtles. There I described the innate neural models of a beach and of the ocean that sea turtle hatchlings use to emerge from their nest and find their way to the water.  I also mentioned, with obvious admiration, their astonishing ability to navigate an ocean as vast as the Pacific by sensing the Earth’s magnetic field. Female turtles use this sixth sense to return to their natal beach, where they lay the next generation of eggs.

Image credit: Mary Wozny

I’ll bluntly paraphrase Fred’s tactfully worded question: “If you think sea turtle behavior is so complex and astonishing, then how can you possibly deny the existence of God, the Intelligent Designer?” I’m guessing Fred has not yet read Appendix 1 of the book, where I explain why “intelligent design” creationism cannot be true. There I point out that biology is full of examples of stupid design: ugly kluges that no self-respecting engineer would ever use. They exist in biology because the illusion of design in living things comes entirely from a mindless, brute-force-dumb algorithm: mutation, recombination, and natural selection. The ass-backwards “design” of all vertebrate retinas, including the two with which you are reading these words, is the example I emphasized in Appendix 1 of my book, but I could just as easily have used sea turtle behavior to make the point.

The most impressive and complex adaptations of sea turtles to life in the ocean center around their need to return to land to lay eggs, which incubate underground and hatch out long after the mother has gone. Without any help or guidance, save for what evolution has programmed into their small brains, the hatchlings must know how to dig themselves out of the sand, how to avoid emergence in daylight, how to find the ocean, and how to navigate away from land once they’re in the surf. All of this complexity could have been avoided by one simple and elegant design change, one that any intelligent designer would have used: live birth underwater.

The fully aquatic olive sea snake (credit: Sylke Rohrlach).

If you’re thinking that reptiles don’t have live birth, think again. Many do, including most species of sea snakes, which, like sea turtles, have adapted to life in the ocean. Unlike the eggs of sea turtles, those of most sea snakes remain in the mother’s oviducts until the hatchlings are fully developed.  The young are born underwater, able to swim off and live independently without ever needing to visit dry land. This not only eliminates the many problems faced by sea turtle hatchlings on the beach, but also frees live-born sea snakes to adapt more effectively to their marine habitat. They are so well-adapted to swimming that they are as helpless on land as the typical fish out of water. Of course that’s not a problem, because they never leave the water.

If evolution could find this elegant and obvious solution for sea snakes, then why could it not also find it for sea turtles? The reason has to do with an important principle of evolution that I explained in the Appendix of my book: evolution can make drastic changes to the form and function of living things, but only as a long series of small changes, each of which must improve reproductive success. This is why evolution never managed to flip the backward retina of vertebrates into the sensible orientation. Although a long sequence of small changes could in principle accomplish this, most of those changes would be harmful to reproductive success. Instead, evolution has made the best of a bad design that forces incoming light to pass through blood vessels, nerve fibers, and several layers of neurons before reaching the light-sensitive cells that detect the image. Evolution minimizes the distortions caused by all the intervening tissue by moving those cells and blood vessels away from the most critical, highest acuity part of the retina, the fovea.

The comparable problem for sea turtles is that their ancestors who adapted to life in the ocean did so without having first evolved live birth. They had to return to land to lay eggs because reptilian eggs laid underwater die from lack of oxygen. For a reptilian species to evolve live birth, the time the eggs are retained internally must gradually increase with each generation, thus shortening the time to hatching once laid. For a land animal, each small change in this direction increases reproductive success if the eggs are safer inside the mother than they are in the nest. This is often true for venomous snakes, but evidently not for the terrestrial ancestors of sea turtles. The sea snakes that give birth underwater to fully developed live young evolved from species that gave birth to live young on land before their descendants made the transition to living in water. This argument also explains why there are a few species of sea snakes that must return to land to lay eggs, just as sea turtles do: their terrestrial ancestors had not evolved live birth before they took to the water, and so, like sea turtles, their descendants are now trapped in an amphibious niche.

Banded sea krait on dry land (credit: Bernard Dupont).

In the light of evolution, the stupid designs seen in biology make sense. They reveal the idiosyncratic turns in the evolutionary history of each species. In the darkness of intelligent design creationism, they are incomprehensible mysteries that reveal the “designer” to be an incompetent and irrational amateur who slaps together Rube Goldberg fixes to problems he has elsewhere solved the right way. A few creationists with legitimate scientific credentials, like Michael Behe, cling to their creationism in the face of this damning evidence by arguing that we cannot impose our will on the mind of the creator, who is free to do whatever he wants in his designs (see chapter 10 of Behe’s book). This dishonest and desperate ploy clearly reveals the unscientific nature of Behe’s thinking on this subject and the pseudoscientific nature of the argument from design. If the divine Intelligent Designer is free to design his creations any way he wants, then any “design” we find in biology, no matter how stupid and klugey, is consistent with intelligent design creationism. This means that intelligent design is untestable and therefore completely unscientific and useless. It has no explanatory power whatever.  Behe’s evasive and disingenuous ploy obliterates the whole premise of so-called “intelligent design theory,” namely, that an intelligent, supernatural god must exist because living things are too complex and perfectly made to have arisen by natural processes.

So why would Behe resort to this self-defeating ploy? I don’t know him personally, so I can only guess, but it probably has to do with the powerful and innate intuitions that give rise to religious belief. Even a scientist as distinguished and brilliant as Francis Collins, the director of the National Institutes of Health, is susceptible to these powerful emotions and the consequent illusion of God’s presence. That insight, of course, was one of the main points of my book and of the talk I gave in Charlotte.

Later in the Q&A period, Fred asked a question about the origin of the universe. To verify that I understood what he was really asking, I rephrased his question as, “Why is there something rather than nothing?”  He accepted this, and I then told him I don’t know the answer. I’d rather leave it unanswered than make up a pseudo-answer that feels good but has no scientific evidence to support it.

The reason most scientists reject belief in God is that religious interpretations of reality are either untestable (and thus scientifically worthless), or, where they do make empirically testable predictions, they fail the tests. One of the main points of my book is expressed in one of its most quotable lines:

Of the billions of people who believe in a personal god, I suspect there are few, possibly none, who came to those beliefs because they lay awake nights worrying about what preceded the Big Bang, or because they found the mechanism of bacterial motility to be irreducibly complex.

Fred’s questions touched on both of these rationalizations religious people use to justify their theistic beliefs. For me the more interesting question is, What really motivates religious belief? My answer now fills the pages of The Illusion of God’s Presence.

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Posted November 2, 2019; Filed under: Ideas, Nature Tags: , , , , , , , , , , , , ,

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