Nathan Lents: Bad Design of the Eye?


(S. Joshua Swamidass) #1

On a TBD date, author and biologist Nathan Lents (@NLENTS) will be joining for conversation about the eye. Nathan recently published a book that is getting a lot of press, and also engagement across the spectrum:

His book has attracted wide coverage, including an opinion peice in the WSJ, and a flurry of 14 articles since April from the DI. In this book, Nathan catalogues several “glitches” in the human body, and stirred up an exchange over whether or not bad design disproves Intelligent Design.

Along with Nathan, I affirm evolutionary science and common descent, but I avoid bad design arguments entirely. There certainly is a long distinguished tradition of this reasoning that traces back to Darwin, and it arises today from Jerry Coyne and even Christians like Keith Fox. Lents is certainly consistent with this tradition, and I am the outlier here.

To be sure, I see the appeal. This one of those arguments that can get scientists rolling with the rhetorical beat of a preacher. It is one of those few places where academics feel the minutia of biology can engage and capture the crowd. I’m not sure this is a helpful way of engaging with audience skeptical of evolution.

I am concerned the “bad design” rhetoric is counter-productive, and if more neutral language would be wise. It might only be preaching to the choir, while undermining trust with others. It seems also to be a selective telling of science. Instead of the language of “bad design”, I prefer instead the more neutral language of his subtitle: “glitches”, and perhaps words like “surprises”, “quirks”, and “seams,” which might instruct us about the non-intuitive features of biology and how we came into being. I would not say loaded words like “botched”, “errors” and “bad design.”

That being said, I’ve noticed that Nathan’s rebuttals of the DI have been more measured. I also recognize that controversy is good for attracting attention around a book, regardless of what exactly is in a book. This brings me to my first question:

  1. Nathan, you’ve been back and forth with Discovery about the “bad design” argument. Is “bad design” really the point of your book? Or is there something more subtle going on? How would you most carefully explain what you are getting at in these exchanges.

Let’s look at a specific example, to make more clear. Nathan wrote about this on his blog (https://thehumanevolutionblog.com/2015/01/12/the-poor-design-of-the-human-eye/). He writes:

The human eye is a well-tread example of how evolution can produce a clunky design even when the result is a well-performing anatomical product. The human eye is indeed a marvel, but if it were to be designed from scratch, it’s hard to imagine it would look anything like it does. Inside the human eye is the long legacy of how light-sensing slowly and incrementally developed in the animal lineage.
https://thehumanevolutionblog.com/2015/01/12/the-poor-design-of-the-human-eye/

These sorts of posts were engaged by the Discovery Institute (https://evolutionnews.org/2018/04/is-the-human-eye-really-evidence-against-intelligent-design/). This seems like an unnecessary conflict to me, unless the goal was conflict itself. This gives a good place to focus in on some good questions about public engagement, and also to learn about the deeper questions that evolutionary science answers…

  1. Nathan, I have several questions on the science here, but will start with one. Do we really know that the retina is “wired backwards”? It seems that the flipped between humans and octopi might just as likely be neutral. And I can even see some very plausible reasons the flipped orientation should be preferred (and I can explain).

There are more questions on the science. Perhaps I will learn something. It seems to me, however, that neutrality on many if these internal details of humans is part of what gives us so much confidence in common descent. If it the retinal wiring is neutral, “design principles” (other than common descent of course) do not make good sense of why chimpanzee and human retinals are both wired backward.

  1. Nathan, several non-scientists on this forum have been asking about the evolution of the eye. This seems like a great way to begin this conversation too. We will save it for the end, but wondering if you can help map out how evolutionary biologists build the case for the evolution of the eye.

The eye loomed large in my story. It arises in anti-evolution arguments all the time, and it initially seems absurd to think it could have arisen by evolution. Raised as YEC, it seemed to be a clear defeater of evolution. The absurdity of seeing camera eyes in both octopi and humans was extreme.

Then, at some point, I tried to understand the reasoning from biology I had rejected. I learned more. I learned of the glitches, and also the lessons of comparative anatomy, and comparative genetics on the eye. It began to become clear. The claim was not nearly as crazy as I had thought. Of course, also, octopi eyes are only superficially like mammalian eyes; the two are very different in their particulars. This is just as we expect from evolution. The argument against common descent had the facts incomplete.


With those three questions guiding us, I’m really happy to have Nathan here. I expect some friendly disagreement, but also common ground. Nathan and I both are in the spotlight at Discovery right now, so this might get more attention than the usual exchange. As is usual for Office Hours, this thread will be tightly moderated.

Kind and respectful questions are welcome. Keep in mind, however, that this is not a forum for endless debate by non-experts. Instead, we encourage everyone to understand and be understood. Make this your goal, and we will all learn a great deal.

Come join the conversation on the grand questions here…


Side Comments on Bad Design of the Eye
Side Comments on Bad Design of the Eye
(S. Joshua Swamidass) #2

(S. Joshua Swamidass) #5

Looking forward to the conversation tomorrow with @NLENTS. When the conversation opens in the morning, let me and Nathan work out a couple things first on the bad design argument. There should be plenty of time to ask follow up questions.


(S. Joshua Swamidass) #6

This topic was automatically opened after 9 days.


(S. Joshua Swamidass) #7

So, last night there was an important conversation that arose that is continuing through today. This is taking more time than any of us expected so we are postponing this dialogue until further notice. Perhaps in a week or two we can pick it up.


(S. Joshua Swamidass) #8

(S. Joshua Swamidass) #9