Assuming the only change is an immediate move to a very high rate of mating (as if people on the planet were paired randomly with one other person) between races/ nationalities/ ethnicities/ whathaveyou, what would the human race look like after X number of generations? Any blue or green eyes left after even a few generations? Would humans all look vaugely Polynesian?
Cecil covered this.
Depends on the value of “X”, and how random you’re talking about-- literally a lottery to mate and everyone could transport anywhere instantly?
But keep in mind genes don’t get “washed out”, so as long as the alleles are still in existance, any phenotype you see today could be produced in the future. There are, what, 6 or 7 billion people in the world right now. It would take countless generations for anthing close to an homogenizing effect to be noticeable.
[Bulworth]
All we need is a voluntary, free-spirited, open-ended program of procreative racial deconstruction. Everybody just gotta keep fuckin’ everybody 'til they’re all the same color.
[/Bulworth]
It just doesn’t work that way. Skin color is determined by several separate genes (I forget how many) and if a child is born to caramel-colored parents, there’s a substantial chance that it will be either distinctly lighter or darker than both parents, simply because they happen to inherit mostly light-skin or mostly dark-skin genes. While a white parent and a black parent will generally have only medium-skinned offspring (because they inherit half light-skin genes and half dark-skin genes), when that child reproduces, random chance could give their offspring mostly light-skin or mostly dark-skin genes.
Cuba and Puerto Rico both have substantial European and African genepools. Despite centuries of mixing, distinctly white or black people are not at all uncommon in either place. Chance means that a certain number of apparently white or black children will pop up from the particular genes they happen to inherit.