Evolution of human colour vision as 'visual purple' receptor proteins, are encoded by Rh1, OPN2 and RHO genes. They are characterized by extreme sensitivity to light and enable monochromatic human vision in low light or dim conditions. They are broken down into retinal and opsin when exposed to these conditions. Humans have 3 types of photopsin proteins found in the cone cells. Long Wavelength Sensitive Opsin (Red cone opsin) – Encoded by the OPN1LW gene with a λmax of 560 that is found in the yellow-green electromagnetic spectrum despite its name. Its sensitivity to the colour red is still known to be higher than the
Evolution of human colour vision with limited colour vision. This is believed to have also been influenced by life styles, including being predominantly nocturnal. There is little data indicating the advantages of UV vision in early human ancestors. Early human ultraviolet vision, or ultraviolet sensitivity, included sensitivity in the wavelength ranges between 400 and 10. These wavelengths are shorter than visible light but longer than X-rays. In some rare cases, some modern day humans can see within the UV spectrum at wavelengths close to 310. In other animals that possess UV vision such as birds, ultraviolet sensitivity can be advantageous for courtship and reproductive success.