Evolution of human colour vision similar. Tritanopes are missing the short wavelength sensitive opsins and see short wavelength colours in a green hue and dim compared to other colours. They may also see some short wavelength colours as black. Other perception problems include distinguishing yellow from pink or purple colours being perceived as shades of red. Researchers have found that trichromacy has advantages over dichromacy or anomalous trichromacy at further distances. This is believed to occur because visual cues such as shape decrease for colour vision as distance increases for targets of a smaller size. Using tests for spotting fruit pieces in bushes at distances
Mammalian eye In the human eye, light enters the pupil and is focused on the retina by the lens. Light-sensitive nerve cells called rods (for brightness), cones (for color) and non-imaging ipRGC (intrinsincally photosensitive retinal ganglion cells) react to the light. They interact with each other and send messages to the brain. The rods and cones enable vision. The ipRGCs enable entrainment to the Earth's 24-hour cycle, resizing of the pupil and acute suppression of the pineal hormone melatonin. The retina contains three forms of photosensitive cells, two of them important to vision, rods and cones, in addition to the subset of