Why did color vision evolve?

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KoosHopeloos

Posted: Tue Feb 13, 2007 6:43 am

Guest

L.S.,

Perhaps a very simple question, but why did (color) vision evolve?

Much is known and speculated on how from a rudimentary eye, vision and
color vision might have evolved, but it seems like a big energy
investment. Also the brain would have to adapt or be able to
interpreted the signals.

But still, why did (color) vision evolve? Wouldn't it be enough to see
in black and white?

I got this question from friend of mine and I was not able to answer
it! And on Google (Scolar) there only thing to find on how it evolved.

Can you point me to some articles, books or websites?

feedbackdroid

Posted: Wed Feb 14, 2007 8:49 am

Guest

On Feb 13, 9:43 am, "KoosHopeloos" <kooshopel...@hotmail.com> wrote:

Quote:

Color vision exists in insects, birds, and many fishes, in additional
to many mammals. You will notice that mammals that evolved to live in
nocturnal environments are mostly colorblind, including rodents, cats,
and canines. In dark nocturnal environments, everything looks black
+white, or shades of grey. OTOH, the world of daylight has natural
color everywheres, including blue sky and green foliage and colored
fruits and flowers. That should be a clue.

Guest

Posted: Wed Feb 14, 2007 8:49 am

On Feb 13, 11:43 am, "KoosHopeloos" <kooshopel...@hotmail.com> wrote:

Quote:

L.S.,

Perhaps a very simple question, but why did (color) vision evolve?
Probably it evolved separately in different lineages for

different reasons. However, I conjecture that the big breakthrough in
color came when the flowering plants first evolved. The flowering
plants evolved colored pigments, in parallel to insects that developed
the color vision. Most flowering plants use insects to carry their
pollen to the ova where the seeds are pollinated. The first flowering
plants probably used scents to attract insects for this purpose. Smell
evolved among animals evolved much earlier, to find food. However,
plants evolved colored pigments to further entice the insects and
insects probably evolved color vision to find the flowers. The feed
back loop resulted in highly colored flowers and highly developed
color vision among insects.
The birds probably followed once the flowers and insects had
developed their symbiotic relationship. Once the flowers had color
pigments, the fruit developed by the flowers probably tended to retain
some of the same colored pigments. Then, some birds evolved the
ability to see colored pigments in order to find and eat the fruit.
Birds that eat fruit sometimes end up carrying the seeds long
distances, on their feathers or in their intestines. So some plants
with slightly colored fruit developed even stronger colors to attract
the birds. This probably started still another feedback loop where
fruit became colored and birds developed feedback loops.
Of course, some fruit eating monkeys eventually evolved colored
vision to take find the colored fruit. And here we are, eating fruit,
birds, and honey.

Quote:

Much is known and speculated on how from a rudimentary eye, vision and
color vision might have evolved, but it seems like a big energy
investment. Also the brain would have to adapt or be able to
interpreted the signals.
Probably not as much investment as you think. At least not

starting from an animal that already has an image processing visual
system. Any eye that uses an imaging system has to use an array of
specialized cells to sense light from pieces of the image. The nervous
system of such an animal would have to already have evolved to process
the image coming from that array. All that is necessary for color
vision is that some of the cells have a different spectral sensitivity
curve than other cells in the array. That would initially come about
due to minute differences in chemical environment.
As an example, the cone cells in human being (a fruit eating
monkey that has recently diversified its diet) have different spectral
sensitivity curves. However, the chemistry of these cones cells is
almost identical. The difference in spectral sensitivity is caused by
slight differences in pH. There is no difference in the pigment
molecule that absorbs the light (rhodopsin) or even in the protein
that embeds the rhodopsin. However, a difference in pH shifts the
absorption curve of the rhodopsin by a very small amount.
Another question would be how the flowering plants evolved
pigments. I may have started with plants that had a variety of
scenting compounds (for attracting and repelling insects). Differences
in the molecules would cause differences in absorption spectra (i.e.,
color).

Quote:

But still, why did (color) vision evolve? Wouldn't it be enough to see
in black and white?
Not for finding fruit.
....references?
I currently have no references on the evolution of color vision.

However, for a general description of the physiology of vision I
recommend two books.
1) Brian A. Wandell, "Foundations of Vision" (Sinauer, 1995). ISBN
0-87893-853-2
Color vision Chapter 9, pp 287-340.
2) David Regan, "Human Perception of Objects," (Sinauer, 2000) ISBN
0-87893-753-6.
Color vision Chapter 3 pp 207-266.

Yes, there are uses for "half-color vision."

Keith Hudson

Posted: Wed Feb 14, 2007 8:49 am

Guest

On Feb 13, 4:43 pm, "KoosHopeloos" <kooshopel...@hotmail.com> wrote:

Quote:

KH:

As I understand it -- as as far as I know is now widely accepted --
colour vision arose in land-based animals in order to distinguish
different fruits -- and, of course, their ripeness. This obviously
won't do for the reason of colour vision in fish but I would guess
that sexual selection might have been the chief factor there.

Keith Hudson

Guest

Posted: Thu Feb 15, 2007 11:11 am

Quote:

This obviously
won't do for the reason of colour vision in fish but I would guess
that sexual selection might have been the chief factor there.

I didn't know fish had color vision. It makes sense in coral
reefs. I notice that fish from cold climates and temperate are less
colorful than fish in tropical climates, especially coral reefs.
Therefore, I doubt that color vision is common in cold temperature
climates where hard corals can't exist.
Coral reefs are colorful mostly because of the algae that live in
hard corals, at least in my conjecture. The lagae that live in hard
corals provide most of the photosynthesis, and therefore most of the
nutrients, that support the animal life. Therefore, I suspect that the
initial impetuous for color vision in coral reefs is for food. In
other words, color vision evolved to find the algae or the animals
that eat the algae (the pigments having colored some of them). If
sexual selection is important for color vision, the color-sexual
attraction may be a secondary adaptation that followed the
adaptation. Coral can't live in cold climates.
Does anyone have a better idea as to why fish in tropical
environments are so much more colorful than fish in reef environments?
The mollusks are similarly less colorful in cold climates.
Furthermore, is color associated merely with reefs or with tropical
temperatures?

Gil Lawton

Posted: Fri Feb 16, 2007 12:21 pm

Guest

Whatever else you read, I would like to invite you to read my message titled
"NSAdvantagism."

It might open your eyes to something you had never thought about; and it
might not.

Basically, it is an attempt by this old layman to articulate what appears to
him to be equivalent to what was meant to be implied by Eugene Ionesco, in
his classic play "The Rhinocerous" -- namely that there are some things in
this world that are so clear and present and large and right in front of our
noses that even some very intelligent people do not see them.

My stance is that, while Natural Selection does, indeed, seem to occur,
contemporary science is only just now in the beginning stages of getting to
know enough to have any idea HOW. But, despite this, a debate rages among
many who
have strongly held, deeply entrenched, highly adamanet opinions which I
think of as the LEGEND of Natural Selection.

Legends are NOT about things that never happened. They are the folk wisdom
and the over-simplified and, often false, analyses that are bought into not
only by the naive public but even by "politically correct thinking"
academics and experts.

Perhaps H. L. Mencken acknowledged that such a phenomenon occurs in regard
to many things, when he said (and I am sure I am getting the idea right, but
might get a word wrong in trying to quote him):

"For every complex thing in this world there is an explanation that is
clear, and simple, and wrong."

But... judge for yourself, after reading my message titled "NSAdvantagism."
At worst, you might get a laugh out of it.

(:>)

g

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