On a bright, crisp December morning I waited in the departure lounge of the Osaka International Ferry Terminal. A great day for the voyage to China: mirror-like sea, very few passengers, golden autumn colours.

A young man in uniform came up to me, demanded to see my passport. He squinted at every visa from many different angles, flicked back and forwards through the pages at least a dozen times, checked the details of every name, date and city over and over again. Then he repeated the procedure. A minute passed, then finally, he handed the document back, looked up and said: "Football!"

He told me he had five days off the following week, and he was flying to England to see his favourite team, Manchester United, in action. And I was spending two days just to sail to Shanghai!

Why would someone fly halfway round the world to see a game of football? And why do people need to become fans, support teams, paint their faces, wave flags, let off firecrackers? What is this human need - this desire to identify with a team: MY team, the blue team, the red team?

Actually this seemingly irrational behaviour makes a lot of sense, both socially and psychologically. For since the end of traditional, village-based communities, where else do people get to be members of a tribe, to share the rituals, symbols, rites and ceremonies of an almost sacred order? Where else can people experience such highs and lows, week in, week out?

On a psychological level, the sports fan will use his team to create a social identity as a member of a group. If the team is successful, the fan shares in the success, experiencing raised self-esteem. Of course, if the team fails, this comparison is no longer psychologically useful to the fan who, refusing to share the idea of failure, is left feeling angry or upset. Put simply: your success is OUR success, but your failure remains YOUR failure.

Many of these processes are unconscious. Raising self-esteem also requires negative feelings to be projected onto the other team's fans - the "out" group. Comparisons with the opposition thus allow the members of the in-group to feel a stronger sense of psychic security and self-worth.

For a while, I had thought I was beyond these influences, and I had become tired of the corruption, excess money, cheating and over-emphasis of football in modern life - the way it had been marketed, turned into a commodity. But last week, as I sat in a pub in Mayfair, the TV burst into life - the World Cup draw! I thought I wasn't interested, but I was wrong. Suddenly I had to know: who was in "our group"? Ah, the USA, Algeria, Slovenia. And Japan? Tough group: the Netherlands, Cameroon, Denmark.

Then the memories came flooding back - where I watched Maradona score his miracle goal against England in 1986, a pile of bodies on a sofa celebrating an England goal against Germany in Italia 1990. Walking into a bar in Milan just as Italy scored their winning goal in the 2006 World cup semi-final. As I pushed into the bar, the whole crowd had jumped in unison, knocking my glasses high into the air then trampling them into a thousand pieces on the floor. The next day, as I retrieved the twisted frames from the bar manager, I didn't really mind...

In his novel Fever Pitch, Nick Hornby describes the suffering of a fanatical Arsenal supporter - the huge joy of celebrating a win, or the total and utter dejection of a loss. In no other area of life, he argues, is it possible to experience such a range of emotions. To some it may seem silly, childish even, for grown men to react like this to the result of a football match. But the fans are fortunate in one respect, since through experiencing these emotions they feel a brief surge of full, total life. And that may be the drug that the fanatical fan seeks.

On another level sport, and especially football, may be seen as a "metaphor for life", and this is something the ancient Romans understood very well, providing free wheat and circus games to the population to keep them happy and under control. Of course, if we look at sport like this, we may see it as one way a power elite can exert control over the masses. However, from another angle, it could also be a way for people to experience group loyalties and inter-group competition in place of nationalism, political violence and war. And surely football, even hooliganism, is better than war?

I won't be painting my face for the World Cup next June, and neither will I be waving flags, wearing football kit. I won't be crying when, as usual, England lose to Germany on penalties. However, my place on the sofa is already booked; the beer is already in the fridge.
I won't be missing any games.