Evolution And History

Primate Characteristics 63

In addition to color vision, anthropoid primates pos-

sess a unique structure called the fovea centralis, or cen-

tral pit, in the retina of each eye. Like a camera lens, this

feature enables the animal to focus on a particular object

By contrast, monkeys, apes, and humans possess
both color and stereoscopic vision. Color vision mark-
edly improves the diet of these primates compared to
most other mammals. The ability to distinguish colors
allows anthropoid primates to choose ripe fruits or ten-
der immature leaves due to their red rather than green
coloration. See this chapter’s Biocultural Connection to
see how our primate ancestry affects our response to
color.

fovea centralis A shallow pit in the retina of the eye that en-

ables an animal to focus on an object while maintaining visual

contact with its surroundings.

Biocultural Connection

Why Red Is Such a Potent Color

The Olympic athletes have been parad-

ing around like fashionistas in an array

of colorful outfits, and we, their adoring

public, can’t resist commenting on the

style and color of their high-end athletic

wear. My favorite was the faux silk, faux

embroidered, slinky red leotards of the

Chinese women’s gymnasts.

Apparently, as researchers have re-

cently discovered, the choice of red for

those leotards might also have given the

Chinese gymnasts an advantage. But

why is the color red so impressive?

The answer lies in our tree-living

past.

In the back of the vertebrate eyeball

are two kinds of cells called rods and

cones that respond to light. Cones take

in a wide range of light, which means

they recognize colors, and they are

stimulated best during daylight. Rods

respond to a narrower range of light

(meaning only white light) but notice

that light from far away and at night.

Isaac Newton was the first person

to hold up a prism and refract white

light into a rainbow of colors and real-

ize that there might be variation in

what the eye can see. Color comes at

us in electromagnetic waves. When the

wavelength of light is short we perceive

purple or blue. Medium wavelengths of

lights tickle the cones in another way

and we think green. Short light wave-

lengths make those cones stand up and

dance as bright spots of yellow, orange,

and red.

Various animals distinguish only parts

of that rainbow because their cones re-

spond in different ways. Butterflies, for

example, see into the ultraviolet end of

the rainbow, which allows them to see

their own complex markings better than

we can. Foxes and owls are basically

color-blind and it doesn’t matter be-

cause they are awake at night when the

light spectrum is limited anyway.

Humans are lucky enough to be

primates, animals with decent color vi-

sion, and we can thank monkeys for this

special ability.

Long ago, primitive primates that

resemble today’s lemurs and lorises

saw only green and blue, the longer

wavelengths of color. But when monkeys

evolved, around 34 million years ago,

their cones became sensitive to even

shorter wavelengths of color and they

saw red.

And what a difference. With red, the

forest comes alive. Instead of a blanket

of bluish-green leaves, the world is sud-

denly accented with ripe red, yellow, and

orange fruits, and even the leaves look

different.

For a monkey leaping through the

forest canopy, color vision would be an

essential advantage. Unripe fruit doesn’t

have enough carbs to sustain a hun-

gry primate and they taste really sour.

Unripe leaves not only taste bad, they

are toxic and indigestible.

For the first humans foraging about

the forest and savannah around 5 mil-

lion years ago, it would have been be

much more efficient to spot a ripe fruit

or tuber than bite into a zillion just to

get the right one. And so humans ended

up with color vision even though we no

longer live in trees.

But color is more than wavelengths,

more than an indicator of ripeness, to us.

Color has become symbolic, mean-

ing it has meaning, and that meaning is

highly cultural.

Chinese athletes and Chinese brides

wear red because red is considered

lucky. The U.S. athletes also wear red

because that bright color is in the U.S.

flag, and because designers of athletic

wear, as well as scientists, know that red

gets you noticed.

BIOCULTURAL QUESTION

While the vast majority of humans see

color as described here, 8 to 20 percent

of human males have red-green color

blindness. Do you know someone who is

color-blind? What could a conversation

with a color-blind person reveal about

the anthropological perspective? What

colors besides red have particular mean-

ings? Do these meanings derive from

biology or culture?

Adapted from Small, M. F. (2008,

August 15). Why red is such a potent

color. Live Science. http://www.

livescience.com/culture/080815-

hn-color-red.html.

The human response to the color red

may well be rooted in our anthropoid

heritage. Could this have given the Chinese

gymnastic team an edge? It is certain

that our ape ancestry contributes to the

human range of motion. While we are all

not able to move in the same ways that

these talented gymnasts can, the human

ability to grasp, swing, stretch, and throw

things derives from characteristics of the

hands and shoulders inherited from our

ape ancestors.

© Cheng Min/Xinhua/Landov