Henry Ford, it is said, commissioned a survey of the car scrap yards of America to find out if there were parts of the Model T Ford which never failed. His inspectors came back with reports of almost every kind of breakdown: axles, brakes, pistons -- all were liable to go wrong. But they drew attention to one notable exception, the kingpins of the scrapped cars invariably had years of life left in them. With ruthless logic Ford concluded that the kingpins on the Model T were too good for their job and ordered that in future they should be made to an inferior specification.

For the automotively challenged, the kingpin is the main pivot in the steering mechanism of a car or other vehicle. Originally this was literally a steel pin on which the moveable, steerable wheel was mounted to the suspension. It is usually made out of metal.

This story, well-known on the internet, was originally told by Nicholas Humphrey in 1976, and often referred to by other biologists including Jared Diamond and Richard Dawkins, the latter recounting the story in what is, by far, the most pessimistic chapter ("God's Utility Function") in his book River Out of Eden.

John Hawks, who has an interesting anthropology weblog takes a look at the Henry Ford story, and why evolutionary biologists seem to love it so:

Of course, the truth is natural selection doesn't cut back the quality of functional parts easily, either. Selection also has to overcome fixed costs in order to change populations: costs stemming from pleiotropy, epistasis, and coevolution with other kinds of organisms (e.g. predator-prey relationships, mutualisms, and mimicry). How much selective advantage can come from reducing femur diameter a smidgeon? It can't be very much, and it might easily be outweighed by the manifold costs of changing osteoblast function to accomplish it. In other words, adaptation is constrained by the same sorts of problems that constrain industry. Ruthless efficiency can rarely be maintained in biology or in manufacturing.

But then again, was the story even true?

Barbara Mikkelson over at the Urban Legends website thinks not, but offers an additional insight:

Though the legend is almost always positioned as a "let's screw the consumers" tale, on rare occasion it has been presented as an example of intelligent design."*

It all reminds me of the Edward de Bono books I read as a kid.

* She includes a similar type of anecdote about another engineering triumph, from WWII:

"A proposal was made to armour bombers in the places where the returning planes showed most damage from anti-aircraft fire. One young analyst suggested that instead, the planes should be armoured where the returning bombers showed no damage. He inferred that the planes that did not return were being damaged in the places that the returning planes were not. His suggestion was implemented and an X% reduction in lost planes resulted."