Vestigial Pattern Bias

two horse chariot

The vestigial pattern bias explains why we get trapped by prevailing wisdom.

In biology, vestigial structures are ones that have no apparent current function and appear to be left over from a past ancestor. Common examples are the human appendix, the pelvic bone of a snake, and the wings of flightless birds.

In business, vestigial structures are ones which exist because “we’ve always done it this way.” Look around and you can find vestigial structures everywhere: the little pocket on the front of blue jeans originally held a pocket watch; arguably it remains solely for historical style reasons.

Coined by Chris Williamson, the vestigial pattern bias reminds us there are consequences for not challenging convention wisdom. His compelling example:

In Ancient Rome, war chariots were built to be the width of two large war horses; that’s the modern equivalent of four feet, eight and a half inches (4’ 8.5’’).

As a result, roads throughout the vast Roman Empire were built to be two-war-horses wide (4’ 8.5’’) to accommodate the war chariots. Everyday carts were constructed to match the width of the war chariots because it caused less damage to the carts to follow the ruts in the road left by the chariots.

When the Romans marched into Britain, they built roads that were two-war-horses wide (4’ 8.5’’). As a result, the tramways across Britain are two-war-horses wide (4’ 8.5’’).

Hundreds of years later, when English laborers built the first railways in America, they used the same tools and specs they were used to: U.S. railroads are two-war-horses wide (4’ 8.5’’).

Now, fast forward to the NASA Space Shuttle which was built from parts made throughout the U.S and assembled in Florida. Because the two large solid fuel booster rocket engines on the side of the Shuttle were sent by railroad, and because the railway line went through a tunnel which was not much wider than the standard 4′ 8.5” track, the rockets themselves could not be larger than the ancient Roman specification.

Essentially, a major design feature of the most advanced transportation system in the history of the world was constrained by a design decision made more than two thousand years beforehand.

Like the parable of 10 Monkeys In The Cage, there’s no one around from the original decision but we do something just because it’s always been done that way.

The vestigial pattern bias is a stark reminder we are often constrained by decisions made by others.

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