title: Bare skin, blood and the evolution of primate colour vision.
abstract: We investigate the hypothesis that colour vision in primates was selected for discriminating the spectral modulations on the skin of conspecifics, presumably for the purpose of discriminating emotional states, socio-sexual signals and threat displays. Here we show that, consistent with this hypothesis, there are two dimensions of skin spectral modulations, and trichromats but not dichromats are sensitive to each. Furthermore, the M and L cone maximum sensitivities for routine trichromats are optimized for discriminating variations in blood oxygen saturation, one of the two blood-related dimensions determining skin reflectance. We also show that, consistent with the hypothesis, trichromat primates tend to be bare faced.
authors.affiliation: California Institute of Biology, Sloan-Swartz Center for Theoretical Neurobiology, MC 139-74, Caltech, Pasadena, CA 91125, USA. changizi@caltech.edu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Changizi
authors.forename: Qiong
authors.initials: Q
authors.lastname: Zhang
authors.forename: Shinsuke
authors.initials: S
authors.lastname: Shimojo
mesh_terms: D000818:Animals; D005075:Biological Evolution; D003118:Color Perception / Q000502:physiology*; D006801:Humans; D010100:Oxygen / Q000097:blood; D010108:Oxyhemoglobins / Q000032:analysis; D011323:Primates / Q000033:anatomy & histology / Q000097:blood / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology; D012867:Skin / Q000098:blood supply* / Q000737:chemistry; D013057:Spectrum Analysis
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen