I started out a Physics major in college, but switched to a Math major. I never even saw a black take a real Math or Physics course. I assume they took the remedial Math course that satisfied the graduation requirements.
At the time I understood why, but had no hard evidence. Herrnstein and Murray provided the evidence.
Bell Curve?
I was a Physics major, and there were a few blacks in the early going (100 and 200 level) but they were in other majors. When you got into the 300 and 400 level physics and math courses there were zero blacks, few if any women. It was whites, (includes Jews, if you want to count them separately, I do not) Oriental Asians and India Indians.
It was the same in the 500 and 600 level graduate courses too. The classrooms had 30 seats or more, at most there were only 10 to 15 students in a class. This was at Cornell in the 90’s.
Nobody partied on friday/saturday night, nobody missed class, nobody did anything but maybe watch football on Sunday afternoon. We studied, we didn’t have time to do anything else.