A counterpart of Based on the colour of one’s skin.
White people are represented as blonde, brunette, red-haired, freckled, tanned, pale, snub-nosed, long-nosed, tall, big, stocky, skinny, short… everyone else gets one look each. And it seems to me that if you can talk about racism as based on skin colour and noses and hair and genitals, it’s not only that you’re locating racism in physical features rather than social attitudes. Racism, after all, is not based on physical features, but the meanings assigned to them. It’s also that you’re playing right back into the assigning of essential physical racial attributes. And it’s funny how white people get the most variety in attributes.
(Not that you’d talk about white people’s genitals, because that would be inappropriate and invasive.)
Because that’s how you get stereotypes about Asians all looking the same, for example: it’s in people training themselves to not see difference. If you’re taught to expect everyone to look the same, you won’t see a difference. Or else, if someone falls outside your idea of what a person of a particular background looks like, you’ll deny their background. (Yes, red-haired and blue-eyed Kashmiri people are really Asian.) This is how we get talk about yellow hordes.
Locating racism in physical attributes means locating race in them. Race is a social construct, and social constructs are where you need to look for racism. Because people look different and are different, and operating in stereotypes means perpetuating them. My point is to take each person on their own terms rather than generic ones, and to recognise that non-white people aren’t minor offshoots of varied white humanity.