Brazil has the highest proportion of so-called "mixed race" people in the world. Yet only 13% of people aged 18 to 24 in that category are enrolled at university. Back in 2012, the government decided to introduce quotas for universities. But recently, the system appears to have stalled. Black student groups have denounced students they say are "too white" to benefit from this affirmative action policy, while universities have set up committees to examine skin color and ethnic background. A programme prepared by Patrick Lovett and Aline Schmidt.