Your eyes evolved to see rosy cheeks.
The eyes in humans and their closest relatives in the primate world are geared to detect subtle changes in skin tone caused by blood oxygen levels, according to a new study from Caltech.
The spectral sensitivity of color cones in humans and chimps are somewhat unusual. Bees have four color cones that are evenly spread across the visible color spectrum. Birds have three color cones. By contrast, humans have three types of cones that are sensitive to a limited range of wavelengths. The closeness, however, allows for the detection of subtle tone changes. … Read more