Evolution of human colour vision lights, which appear to be clear. Other colour perception issues include having trouble distinguishing yellows from reds and violet, lavender and purple from blue. In other cases, objects that reflect both red and blue light may appear to just be blue to these individuals. Deuteranopes, who are missing medium wavelength sensitive cones, are similar to protanopes in that they cannot distinguish between colours in the green-yellow-red part of the electromagnetic spectrum. However, deuteranopes do not suffer from dimming issues. For example, purple colors are not seen as being opposite to other colours in the spectrum but instead appear to be
Blue-and-yellow macaw "Ara" (Lacepede 1799), one of six genera of Central and South American macaws. These birds can reach a length of and weigh , making them some of the larger members of their family. They are vivid in appearance with blue-green wings and tail, dark-blue chin, golden under parts, and a green forehead. Their beaks are black. The naked face is white, turning pink in excited birds, and lined with small, black feathers. Blue-and-yellow macaws live from 30 to 35 years in the wild and reach sexual maturity between the ages of 3 and 6 years. Little variation in plumage is