Stupid design

Natural History, Feb, 2006 by Bill Schubert, Judith S. Weis, Jim Peck

I am an engineer, not a biologist, but I agree with the point made by Neil deGrasse Tyson in his article "The Perimeter of Ignorance" [11/05]: we are not engineered intelligently. A good engineer would have placed a single ear on top of our heads so we could hear equally in all directions (with proper guarding for rain runoff, of course). Surely we would be able to breathe and swallow at the same time. And wouldn't a tail still come in handy to hold a flashlight when we have one wrench on the bolt and another on the nut?

Bill Schubert

Twin Lake, Michigan

Neil deGrasse Tyson criticizes the eye as an example of poor engineering because it can't detect ultraviolet, infrared, and other wavelengths of radiation. Biologists have another reason to see it as an example of unintelligent design: the retina is oriented backwards, with the sensory cells located at the back. Light must travel through layers of nerve cells in order to reach the sensory cells, which is a most inefficient design.

The arrangement makes sense only if the embryonic development of the optic cup is understood as an outgrowth of the brain. In the vertebrate embryo, the cells that will become the sensory cells of the retina are initially located on the outermost layer of the body. The brain then develops as an "inpocketing" of the outer layer of the embryo. Presumably our distant ancestors developed light-sensing cells on the outside of their bodies, where the light would hit. Evolution is the only way to make sense of the backwards retina.

Judith S. Weis

Rutgers University

Newark, New Jersey

My favorite example to add to Neil deGrasse Tyson's list of "clunky, goofy, impractical" designs is the left recurrent laryngeal nerve. The larynx is supplied by branches of cranial nerve X. Two of those branches are the recurrent laryngeals, which, instead of branching off at the level of the larynx, originate in the chest. Furthermore, the left recurrent laryngeal is nine inches longer than the right one. Because both recurrent laryngeal nerves are so long, they are at greater risk of injury, including (in modern times) from surgery in the neck or upper thorax. Why would anyone design such an arrangement? It's a pure accident of embryonic development.

Jim Peck

Jackson, Mississippi

EDITOR'S NOTE: The following e-mail exchange began as a letter from James Caggegi, a reader in Tustin, California, regarding "The Perimeter of Ignorance." Neil deGrasse Tyson's responses were made as interpolations within the body of the e-mail, and are reproduced here in italic.

JAMES CAGGEGI: Mr. Tyson, the human body's design, though faulty by your standards, is a design nonetheless. And a design presupposes a designer. Now, whether the designer is "time and chance" or an "intelligent designer" is a battleground for debate.

>> NEIL DEGRASSE TYSON: My opinion is not particularly relevant here. I simply asserted that, by the standards of any sensible engineer, the human body is also faulty or underequipped.

JC: I am not a scientist, but I know the definition of "science" is knowledge.

>> NDT: Although I've never been a fan of debates over word definitions, I think it's important to note that science is a process of knowing, not the knowledge itself.

JC: It seems you've forgotten that what you are espousing is not knowledge but theory, or the pursuit of knowledge.

>> NDT: That's as good a definition of science as any. JC: Maybe those who believe in the possibility of an intelligent designer are not "embracing ignorance," as you say, but rather have opened their minds to the idea that there might be something (or someone) supernatural revealing itself through nature.

>> NDT: Those who use nature as a record of an intelligent designer are being highly selective about what evidence they cite in its cause. And while I made that point semicomically, it remains philosophically serious: if there is a higher designer, why do the workings of nature suggest abject stupidity as often as intelligence?

JC: Is it ignorance to say that nature reveals an intelligent designer and to ask for what purpose we could have been designed?

>> NDT: You can only think that statement is true if you selectively ignore deep and unlimited evidence to its contrary. In which case, yes, it is ignorance to make such an assertion.

JC: Maybe you are mistaking ignorance for humility--something hard to find in the scientific community.

>> NDT: Again, I do not like arguing word definitions, but if humility, as you use it, means being so deeply moved by what you do not understand that you credit a higher intelligence, thereby abandoning any further investigation into its causes, then yes, there is not a single humble scientist out there. Or rather, if a scientist credits a higher power, then one of two things is true: Either the scientist feels that way about a subject outside his or her research expertise. Or, if the subject does fall within his or her expertise, the scientist will never make discoveries about it.

JC: You say that intelligent design belongs in the realm of religion, philosophy, or psychology, but "not in the science classroom."