virus: purple dinosaurs

Eva-Lise Carlstrom (
Wed, 24 Sep 1997 15:05:17 -0700 (PDT)

On Wed, 24 Sep 1997, Reed Konsler wrote:

> What do you mean by "exist"? How do you determine the existence of something?
> Our observations of the universe imply that it had a history prior to the
> arrival
> of homo-sapiens. What was the skin color of a T-Rex? Purple?

This question has been made much more interesting for me by Dennett's
pointing out, in _Consciousness Explained_, that color is not a simple
product of qualities of light; it is a combined product of qualities of
light with evolved visual functions. The colors of many natural objects
have evolved simultaneously with the ability of organisms to perceive
them; if no animal had evolved color vision, strawberries would in
all likelihood not have evolved the quality our eyes and brains
perceive as redness. Since, at the time of T. rex, there was no primate
color vision, it might actually be meaningful to say they had no color, as
we perceive it. Of course, there may have been dinosaurs with color
vision, possibly even better than, or at least different from, the human
version. And any such view of things doesn't change the fact that, were
we able to transport a T. rex forward so we could look at it, we would
indeed see some color(s) or other. We might miss the ultraviolet stripes,
though. :)

off on a tangent, trying hard not to think of Barney