[wardaddy]

Not to mention differences between the tolerance of cold and heat. I have lived and worked the world over in many varied racial cultures/environments. For me to deny that there are at least superficial differences obvious even to my untrained eye would be self denial of my own observations.

[ConsistentLibertarian]

It's an error in salience. There are probably unrelated statistical differences between people to whom fennel tastes bitter and people to whom it does not. But that clustering of characteristics doesn't jump out at us the way skin pigmentation does. We'd have a hard time even thinking there's a non-random connection even after we convinced ourselves through carefull observation that the satistical differences were real. But when we see statistical differences between people with different skin pigmentation, for some reason, it stirkes people immediately as salient and it's hard for many people even to think it's an accidental connection with no deep explanatory or causal significance.