One of the important drainage-collection pipes is installed near the top of the largest pair of cavities, the maxillary sinuses, located underneath the upper cheeks… Putting the drainage-collection point high within these sinuses is not a good idea because of this pesky thing called gravity.
Lents misunderstands the physiology of sinus drainage. The visible opening (ostium) in the maxillary sinus is not the only, or even the main, route of drainage. There is a complex system of interconnection, often at the microscopic level, between the paranasal sinuses, and Lents betrays an ignorance of sinus physiology in asserting that the large visible opening out of the sinus, which is indeed located at the upper wall of the sinus, is the primary physiological route of drainage.
In reality, the paranasal sinuses drain by very complex pathways, with many accessory ostia and via several (rather ingenious) interdependent pathways. Furthermore, they don’t drain primarily by “gravity,” as Lents naïvely asserts. Ciliary action moves secretions along to a network of drainage channels. It is perhaps best to think of the large ostium on the upper wall of the sinus as an “overflow” channel, analogous to the overflow opening in your sink. It is not meant to conduct the main flow of fluid in the sinus. In fact, it can’t be the main outflow path, because it is high in the sinus yet the sinus is not often filled with fluid.
From design considerations, it can be inferred that a drainage ostium in the floor of the sinus would drain at too high a rate, drying out the sinus mucosa and predisposing to plugging of the ostium by thick debris. More.
“Bad design” is, in general, a poor argument against design. A design in nature weighs alternative constraints for a transient life form in a specific, limited environment. It does not weigh an existing design against a Platonic ideal. Life forms in nature are almost always optimally designed but never ideally so. They also feature built-in obsolescence and ecology-friendly weaknesses that limit their population growth.
Anyone who designs neighbourhoods, school lunch programs, or traffic routes will be aware of the challenge of optimization. But the concept remains forever a mystery to some.
External testicles another instance of bad design? Oddly, in making such a dramatic claim (“there is no good reason that sperm development has to work best at lower temperatures”), Lents does not quote any expert on the subject of temperature and sperm development.
Jonathan Wells on Lents’s claim that the human eye is wired backwards