RIO DE JANEIRO — Amid the kaleidoscope of skin colors that is modern Brazil, Diego Souza Barreto is like millions of other young men: He has a cinnamon complexion and features that borrow a little from Africa, a little from Europe and maybe a little from the Middle East.
A few months back, when he applied for college, Souza Barreto had to "self-define" his race for the first time. He chose the box marked pardo, which means brown or mixed race. "For me, pardo is a meaningless term," he said, frowning. "It's a word used to describe an envelope."
Diego was one of thousands of students to enter the State University of Rio de Janeiro this year as part of its new racial quota program. Never before had race been used as a criterion for admission to a Brazilian public university.
The quotas are an experiment in social engineering that many blacks here hope will help spark a revolution in race relations in Brazil. But at the State University of Rio, the attempts to redress the country's historic inequalities have plunged the campus into the complex and often bewildering world of racial identity.
Race here is a notion beset by paradoxes. Blacks and whites intermarry more commonly, perhaps, than anywhere else. Yet there is a clear racial divide between rich and poor.
"Brazilian law has always tried to deny that race exists," said Paulo Fabio Salguiero, the university's admissions director. "When slavery was abolished, all the records of the slave holders were destroyed."
Brazilian slavery was a less rigid institution than its American counterpart -- a black slave, for instance, could buy his freedom -- but Brazil was the last country in the Western Hemisphere to abolish slavery, in 1888.
Now, race is at the center of the admissions process, even though it isn't always clear who is black and who isn't.
In Brazil, the national myth has it that everyone, no matter how fair-skinned, has at least one drop of "black blood." But there is also an inflexible racial pecking order: Walk into an upscale boutique or a corporate boardroom in this and other Brazilian cities, and black people all but disappear.
"The world is beginning to realize this other truth about Brazil -- that we are a country where racism has produced one of the most effective systems of domination in the world," said Ivanir dos Santos, one of Brazil's most prominent black activists. "Without a single law in place to support it, we have a hierarchy of skin color where blacks appear to know their place."
Dos Santos and other activists here say quotas at Rio's university and other reforms are long overdue. They see the university's step as the first in a Brazilian "reconstruction," like the 20th century revolution in civil rights that finally began to chip away at the legacy of slavery in the United States.
But, as in the United States, where racial quotas in university admissions were declared illegal in the 1978 Regents of the University of California vs. Bakke decision, the Rio plan has provoked an angry backlash. About 300 students have filed lawsuits against the quotas, and the state government has scaled back the program for next year.
In the Rio quota system's first year, 40% of admission slots were reserved for black and pardo students and half for students who had completed all their schooling in public institutions (one student could fill quotas in both categories).
"Any quota system is wrong because it discriminates against white students for the crimes of the past," said Jair Bolsonaro, a federal congressional deputy representing Rio. "I'm Italian. My father and grandfather were Italian. None of them had anything to do with slavery."
To these arguments, black activists respond with statistics illustrating glaring racial inequality. Blacks make up 2% of the nation's university students, even though nearly half of all Brazilians defined themselves as black in the most recent census.
Go to nearly any public university in Brazil, Dos Santos said, and you will be lucky to find even one Brazilian-born black in its medical school. "The only blacks are the exchange students from Africa," he said.
"We pay our taxes," he added, "so why shouldn't we receive this public service we're paying for, and which supposedly belongs to everyone?"
At the State University of Rio, putting the quota system into practice has been a bureaucratic and pedagogic nightmare that illustrates how deeply rooted Brazil's ethnic hierarchies are.
None of the students admitted through a quota received financial aid or counseling during the first semester. Although tuition is free, buying a dozen new books each term, in addition to other materials, is beyond the reach of many working families. Some students were so pressed for cash, they put on their old high-school uniforms to take the bus to campus -- in Rio, high school students can ride city buses for free.