1.44. Human Vision http://www.ck12.org
FIGURE 1.84
Humans with color vision see the apples
on this tree; the bright red color of the
apples stands out clearly from the green
background of leaves.FIGURE 1.85
Dogs and cats would see the green and
red colors as shades of gray; they are able
to see blue, but red and green appear the
same to them.primates survive.
Primate ancestors also mainly ate fruit. They needed to be able to spot colored fruits in the leafy background of
the trees (Figure1.86). They also had to be able to judge which fruits were ripe and which were still green. Ripe
fruits are usually red, orange, yellow, or purple. Being able to see in color was important for finding food. It was an
adaptation that would help fruit-eating primates survive.
Vocabulary
- vision: Detecting light with the eyes and forming images.