It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Thank you.
Some features of ATS will be disabled while you continue to use an ad-blocker.
Tetrachromats can see colors that most people cannot — up to 100 million, estimates suggest, which is 100 times that of the average human. Most people have three cells, or receptors, in their retinas, but tetrachomats have a fourth receptor, which may be what allows for their heightened color perception. They are usually female, and it’s estimated that about 12 percent of women carry the gene for this fourth receptor.