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24

The uniqueness of irises and fingerprints are, as you said, limited to the number of possible permutations of irises and fingerprints. A similar problem exists in computer science, and is known as a hash collision. Given sufficient samples, there will always be a collision for a hash of finite size. However, the sample space is sufficiently large for iris ...


23

The blue colour is an example of structural colour, caused by light interacting physically with something. Some examples of structural colour are the iridescence of insect wings and body surfaces (usually caused by repeating chitinous structures), and of certain birds feathers, as well as the non-iridescent colours of the blue and yellow macaw. In the case ...


17

The generation of iris color is quite complex and the exact color of the eyes depends upon many different factors, not just melanin. In fact, blue coloration does not depend on a specific chemical, but on the structure of the eye itself. This very nice review (free) summarizes our current understanding: Genetics of human iris colour and patterns - Sturm and ...


10

Firstly, note that "eye color" is actually iris color. The person with a lighter iris will have more straylight compared to person with brown iris: The graph represents Intraocular straylight of the age-matched groups. Participants with light-blue-colored iris showed significantly higher values for intraocular straylight than those of the other groups. ...


6

@March Ho's answer is an excellent answer based on the assumption that all of the observed phenotypic variance is due to genetic variance. Environmental variance The genetic variance is not the only underlying variance that can explain variance in phenotypic traits. There is probably quite a lot of phenotypic variance that is caused by the underlying ...


4

Short answer No. Not two irises are alike, including the irises of identical twins and even the two irises of one and the same person. This uniqueness of the human iris is used in iris scans. The variety of the iris is caused by its complex structure and coloring pattern. Source: Jean-François Mainguet Background The iris is explained on Biometric ...


2

Imagine the iris like a shutter in front of a focussing lens (which, in fact, it is; see the diagram). This means that any light going through the iris will be focussed on a very small point on the retina, and your eye is wonderfully developed in a way that this exact spot is the fovea, the only spot in the retina that allows you to see colour and high-...


1

Mammals are born with blue eyes because the melanin level has not yet been established to give brown/yellow. Blue is the absence of melanin, so that eyes reflect outside light which is seen as blue. Melanocyte cells respond to light and will start to make melanin in the first few weeks after birth. Melanocyte cells have a range of activity and will produce ...


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