poly: Why is brown common?

From: Carl Feynman <carlf@alum.mit.edu>
Date: Thu Feb 05 1998 - 13:53:56 PST

Okay, all you polymaths, here's a question that's got me stumped: why are so many substances brown?

Plants are green, the sky is blue, and almost everything else is white, black or brown. I can understand why things are black, white or gray: that's just reflecting a certain amount of light regardless of frequency. But why brown? Like most humans, I have brown hair and brown skin, I eat brown food which I convert into brown shit, I live in a house made of brown wood set among brown-barked trees next to a brown meadow. The earth under the meadow is brown, and the rocks around my house are brown with iron oxides for their first few decades above ground (then they turn gray). Maybe I've just been in a New England winter for too long, but it seems like far too many things are brown.

Some hypotheses:

The darwinian hypothesis: Our visual system didn't evolve the ability to distinguish between colors for unimportant objects (dirt, trees, dead leaves), so they all get classified as brown. But people are not uninteresting, and they're brown. Ditto prey animals and predators.

The maxwellian hypothesis: There is some physical effect that frequently produces a red-heavy reflectance spectrum that we identify as brown. I vaguely remeber from my undergraduate classes in electrical engineering that is it common for the amplitude response of circuits to decrease by 3 db for every octave of increased frequency. Perhaps a 3 db/octave roll-off in the optical range looks brown.

The whorfian hypothesis: it's just a cultural fluke. Other languages have six words for the color we English-speakers think of as brown, so no 'brownish' color is particularly more common than any other color for people who speak those languages. In fact, they wonder why so many things are greenblueyellowred, since they lump all those colors together. This may be contradicted by anthropological data.

Received on Thu Feb 5 22:07:14 1998

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