In Brazil I glimpsed a possible future in which there is only one race

Some time ago, Brazil's census takers asked people to describe their skin colour. Brazilians came up with 134 terms, including alva-rosada (white with pink highlights), branca-sardenta (white with brown spots), café com leite (coffee with milk), morena-canelada (cinammon-like brunette), polaca (Polish), quase-negra (almost black) and tostada (toasted). This often lighthearted poetry of self-description reflects a reality you see with your own eyes, especially in the poorer parts of Brazil's great cities.

Walking round the City of God, a poor housing estate just outside Rio de Janeiro - and the setting for the film of that name - I saw every possible tint and variety of facial feature, sometimes in the same household. Alba Zaluar, a distinguished anthropologist who has worked for years among the people of the district, told me they make jokes about it between themselves: "You little whitey", "You little brownie", and so on. And those features, with their diversity and admixture, are often beautiful.

Brazil is a country where people celebrate, as a national attribute, the richness of miscegenation, giving a positive meaning to what is, in its origins, an ugly North American misnomer. There is, however, a nasty underside to this story. "Racial democracy" is an established, early 20th-century Brazilian self-image, by contrast with a then still racially segregated United States. Yet the reality even today is that most non-whites are worse off economically, socially and educationally than most whites. And part of this inequality is due to racial discrimination.

I went to Brazil asking questions about poverty, social exclusion and inequality. Within minutes, my interlocutors were talking about race. This happened too in a conversation with the impressive former president, Fernando Henrique Cardoso. In a vivid memoir, The Accidental President of Brazil, he recalls his own research as a young sociologist in the shantytowns. Noting the extensive blending of the races, he none the less concluded that "in general terms, to be black was to be poor in Brazil".

To address this problem his government initiated affirmative action programmes, and these have grown under President Lula. Many universities now have quotas both for applicants from state schools and for black undergraduates. Those for black students are the object of fierce controversy. First, there are objections of principle. Maria-Tereza Moreira de Jesus, a black poet and writer, has said: "Racism exists, from how one is treated in a shop to being interviewed for a job, but basing entrance on race is another form of racism." A black rapper in a shantytown in Sao Paulo, MC Magus, told me he thought such quotas were a bad idea. "We are all equal," he said.

There is also a practical difficulty. In such a mixed society, how do you decide who is black? The problem was graphically illustrated by the recent case of identical twins, Alex and Alan Teixeira da Cunha, who both applied to the University of Brasilia under its quota scheme. Alan was accepted as black, Alex rejected as not black. The university actually has a commission that determines race on the basis of photographs of the candidates, using phenotypes including hair, skin colour and facial features. The person who first told me about this was Jewish. "You can imagine what I think of it," he said.

Some of the country's very active black movements prefer the term "Afro-descendant". But a recent scientific study of mitochondrial and nuclear DNA estimates that upwards of 85% of the population - including tens of millions of Brazilians who regard themselves as white - have a more than 10% African contribution to their genome. Those early Portuguese settlers usually didn't bring their wives with them.

That leaves the subjective self-definition Brazil has traditionally used. Recent figures from the official institute for geography and statistics suggest that some 50% of Brazilians classify themselves as "white", a little more than 40% as "brown", just over 6% as "black", and less than 1% as "yellow" - that is, of Asian, especially Japanese, descent - or "indigenous". These are direct translations of the five categories offered. In a bold move, representatives of the black movements, some of them supported by North American foundations, have proposed that the whole non-white population should be classed as black. Then everything would be simple - black and white.

Others cry in horror that this would be to import the worst of American-style racial classification and to deny the whole Brazilian specificity of miscegenation. If there really have to be university admission quotas by colour - something courts in the US have declared to be discriminatory - let them at least be based on the traditional Brazilian method of self-identification. In the past people have tended to define themselves as being towards the lighter end of the spectrum, especially as they became more prosperous. "Money whitens," a sociologist dryly observes. If quotas were to result in a few more people preferring to be black, so be it. After so many centuries when it was more advantageous to be white - slavery was only abolished in Brazil in 1888 - there's a case for stacking the cards just a little the other way. And if that means that one day a girl most people would consider to be white applies to university as black, well, good luck to her.

As a non-Brazilian, I am in no position to adjudicate on this argument. I can see the powerful case against colour quotas; I can also see the tough, inherited reality of discrimination that must be addressed. Brazilians will decide this themselves. But I would say with all my heart that I hope Brazil moves closer to making a reality of its old myth of "racial democracy", rather than retreating to anachronistic racial pigeonholing and the reduction of complex identities to a single attribute. For what I discovered in Brazil is also an anticipation of all our futures, in a world where peoples will be increasingly mixed up together.

I realise, of course, the danger of seeming like an affluent, white outsider - well, not so much white as alva-rosada, particularly after a fortnight in the Brazilian sun - who sallies into the shantytowns for a few days and exclaims: "How beautiful these people are!" I could write the satire myself. Yet I will say it. What I glimpsed in Brazil, even amid the poverty and drug-driven violence of the City of God, was the beauty of miscegenation. I learned to celebrate it from Brazilians themselves.

It is precisely this mixing that has helped to make Brazilians among the most handsome human beings on earth. What is foreshadowed here - but I repeat, only if Brazil can correct its dreadful social and economic imbalances, including a heritage of discrimination - is the possibility of a world in which skin colour is nothing more than a physical attribute, like the colour of your eyes or the shape of your nose, to be admired, calmly noted, or joked about. And a world in which the only race that matters is the human race.

Timothy Garton Ash