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
Eye-ring white eye-rings may consequently express vigorous health. In addition they may signal membership of a particular group or population, as different species and populations may have rings of differing colour, size, shape or completeness. These recognition signals could then play a role in reproductive isolation and speciation. Eye-ring The eye-ring of a bird is a ring of tiny feathers that surrounds the orbital ring, a ring of bare skin immediately surrounding a bird's eye. The eye-ring is often decorative, and its colour may contrast with adjoining plumage. The ring of feathers is sometimes incomplete, forming an eye arc. In the