Evolution's Bug Tracker: 13 Anatomical Flaws in the Human Body

Biologist Lewis Held catalogs human anatomical quirks that range from harmless oddities to lethal design failures, framing them as evidence of evolution’s tinkering rather than intelligent design. The retina is wired backward, with photoreceptors sitting behind ganglion cells and creating a blind spot the size of nine full moons that the brain papers over via interpolation. Teeth crowd because our jaws shortened faster than our dentition, and human embryos still grow vestigial branchial arches inherited from fish ancestors.

The more dangerous flaws stem from shared plumbing and bad routing. The epiglottis multiplexes air and food through the same passage, making choking possible — a tradeoff for speech, since infants and other mammals route air separately and cannot talk. The urethra threads through the prostate, inviting strangulation when the gland enlarges with age. May-Thurner syndrome causes left-leg clots because the right iliac artery crosses over and compresses the left iliac vein. Ectopic pregnancies occur because the oviduct is a detached tube rather than a direct ovary-to-uterus connection. Childbirth requires the fetal skull to rotate 90 degrees through a pelvis barely wide enough to accommodate it.

Held invokes François Jacob’s observation that building a lung from a piece of esophagus is tinkering, not engineering. The piece’s underlying argument: these are local optima evolution got stuck in, not features — and a sufficiently advanced alien glancing at the Pioneer 10 plaque would notice.