## Evolution of Colour

From: andrew cooke <andrew@...>

Date: Sun, 11 Dec 2011 17:56:25 -0300

OK, so here's a possibly interesting question that just came up while talking
to Paulina: how did colour vision evolve?

You might answer: so that animals could see more detail.  But what would they
see?  Most natural things are either brown or green.  And the blue sky.  Is
that enough to motivate three colour vision?

"What about colourful flowers, or fruit, or birds?" you might ask.  But then
how did *they* evolve?  Because I would have thought that the standard
explanation there is that they are evolved to be attractive to colour vision.

So apart from green / brown / blue, we seem to have a chicken and egg
situation: bright plumage / fruit / flowers wouldn't evolve until there was
colour vision to detect them; but without them, why evolve colour vision?

Presumably things boot-strapped on green / brown / blue and then more
resolution / brighter colours co-evolved.  Which I guess works, but isn't as
cute a "just so" story as you might hope.

Or maybe there's some technical argument that says that green / brown / blue
requires three detectors (why not two?)...

Andrew

### evolution of color vision

From: Stefan Wehner <stefan@...>

Date: Sun, 11 Dec 2011 19:31:26 -0500

I remember too, it has to do with the color of fruit and the different =
hues of green (and even red) which mark the younger and more nutritious =
leaves. A couple of years ago I read a book about evolution: Sean B. =
Carroll: The making of the fittest. It devotes a whole chapter on the =
issue and goes into the details of which molecules are responsible for =
which color, what are the genes that codify them and how these genes =
shifted between different animals. By the way, only the Old World apes =
have trichromatic color vision. American monkeys as well as rodents and =
other mammals only developed dichromatic vision. Birds and even fish can =
see colors and it seems that color vision was acquired early in =
evolution, then lost in many species and subsequently redeveloped. =
Pretty fascination topic and I can recommend the book.

Stefan=

### Seeing red

From: Manuel Simoni <msimoni@...>

Date: Sun, 11 Dec 2011 22:07:47 +0100

From Wikipedia's http://en.wikipedia.org/wiki/Evolution_of_color_vision

"Ability to perceive red and orange hues allows tree-dwelling primates
to discern them from violet. This is particularly important for
primates in the detecton of red and orange fruit, as well as
nutrient-rich new foliage, in which the red and orange carotenoids
have not yet been masked by chlorophyll."