The sweaties are particularly good at sports of little consequence. Curling and tossing whatever it is they toss ..... mostly each other on a Saturday night.
Its all down to Gene Variance, hence you get big black tribes AND PYGMY TRIBES.
IQ variance is slighley different and still remains after cultural factors are removed.
ie Female IQ's are an average of 4 points lower than males, this difference when measured in Extremes explains why most Nobel winners for science and most retards are male.