The variation ( as calculated by https://en.wikipedia.org/wiki/Covariance
) in both the eye color and in the folds of the rods/cones in a human eye broken out in histogram by race, shows a linearly proportional relationship to the overall speed of evolution in that race between generations, since the eye is a sort-of glass hole, or a small peek into the brain structure layout of the brain. Which also varies and splices in the same way the layout of the fovea does.
You know how sharks have been frozen into time over the lsat 700 million years, but lemur descended hominids change, it's because certain DNA
from certain human races evolve faster, they have a higher "learning rate".
This "Gamma Learning rate" of evolution, can be lifted off a photograph of an eyeball by machine learning. https://en.wikipedia.org/wiki/Q-learning#Learning_Rate
Get back to work.