Nathan Lents on our imperfect body

Nathan Lents, professor of biology at John Jay College, has written a book which describes some of the imperfections of the human body. Beyond being entertaining bits of medical trivia, these are also part of what prompted Charles Darwin to formulate his theory of evolution. The idea that much of our biology demonstrates what can only be considered “stupid design” not only serves as an effective counterargument to the claims of creationism. It also helps correct the misunderstandings of many people who accept evolution, but view it as primarily driven by natural selection and constantly seeking the best possible design for an organism. The truth is that evolution largely proceeds by accident and luck, both good and bad, and rarely if ever arrives at a solution of the sort that would be found by careful advanced planning.

Lents gives a summary of his book in the lecture below. It’s well worth watching, but I’ll just give one example as an appetizer: I recall in medical school reading speculation on why our skulls evolved to have these large, empty cavities (the sinuses) that seems to serve primarily to as a reservoir for infections. Some of the explanations comtemplated included that they served to help moisturize the air we inhaled, or to make the timbre of our voices more pleasing, or to reduce the weight of our skulls. None of these seemed particularly convincing, but the non-adaptationist account that Lents describes is quite persuasive: Most of our mammalian cousins primarily navigate the world thru smell rather than vision, and this is why they have long snouts. The structures in their skulls that are the equivalent of our sinus cavities are packed full of olfactory receptors. However, humans and other primates rely more on vision, which works better without a large snout in front of our faces obscuring the view. So, over the course of evolution, our faces have flattened as our eyes moved forward, and along with this our sinuses have moved up into our cheeks. It’s a bad design which produces no benefit for us whatsoever. However, a proper understanding of evolutionary theory explains why this physical trait exists.

That is just one of the examples he gives in the lecture which is linked below. Enjoy: