In total, the average British person has sex 2,580 times during his or her lifetime, with five different people. However, they are also about the most unfaithful in Europe, with 42 per cent admitting to sexual infidelity.

Perhaps more shockingly, Italian men - dark, suave and sophisticated, and the supposed dream lover of every British woman - are revealed as the pandas of the Continent.

Their reputation as the world's hottest sex machines is shattered by a barrage of humbling statistics that reveal the naked truth: they start having sex late, they don't have it often, and when they do it's all over in the blink of an eye. In fact, Italians are the least sexually active people in Europe, and when they do have sex, it lasts the shortest time.

Every day 120 million acts of sexual intercourse take place around the world - resulting in 910,000 conceptions. On average, it lasts 21 minutes in the UK, compared with 17 in Germany, 14 in Italy and 10 in Thailand (where they do it quickest). The Brazilians, who average 30 minutes, are the world's sexual gold medallists (although 44 per cent of Brazilian women confess faking orgasms).

The Penguin Atlas of Human Sexual Behaviour - a serious academic study dressed up as soft porn - categorises each nation by its most intimate details, painting a fascinating but often bizarre insight into different cultures.

The revelations can be unflattering: 46 per cent of American women think a good night's sleep is better than sex. They can be disturbing: 23 per cent of Germans are sexually stimulated by underarm odour. And they can be upsetting: in Egypt, 80 per cent of women suffer female genital excision,although it is banned by law.

The author, Professor Judith Mackay, an adviser to the World Health Organisation and a fellow of the Royal College of Physicians, also helps explain the behaviour of certain relatives: 'Some aged ants, aphids, wasps, bees, naked vole rats and Caribbean snapping shrimps abandon procreation and invest their energies into helping relatives' genes survival,' she writes.

It isn't only the Italians who have their reputation shattered. Irish women - often portrayed as good girls oppressed by the weight of Catholicism -lose their virginity at 16, younger than most other women in Europe, a year before Swedish women and two years before British ones.

Other stereotypes are dramatically confirmed. Gallic pride is unchallenged, with the French having the most sex of anyone in Europe, doing it more than 130 times a year. Apart from the Irish, women from Finland, Denmark and Iceland are the most sexually advanced in Europe: on average, they lose their virginity at 16, and by the age of 18 around three-quarters of them are having sex.

In Europe, it's in the traditional Mediterranean countries that women develop latest. Only one in four women of 18 in Greece and Portugal is sexually active, and on average they wait till they are 19 to lose their virginity.

During the Second World War, jealous British men dubbed Americans as over-sexed, and little seems to have changed.

By almost all measures, Americans are more sexual than British people. Both men and women lose their virginity younger, and they have sex more times a year than their limey counterparts - and the sex lasts a lot longer (well, seven minutes).

However, the US is bucking one global trend. Whereas in most of the world, young people are becoming sexually active at an earlier and earlier age, it is rising in America - possibly as a result of increasing sex education. High school children are more likely to be virgins - and less likely to have had multiple partners - than they were 10 years ago.

Even so, the West is revealed as being far more sexual than developping nations - with the exception of Africa.

In the West, men and women lose their virginity at about the same age. But in most developing countries, women become sexually active much later than men. In Kazakhstan, Thailand, Ecuador and the Philippines, women usually lose their virginity after the age of 20.

In many developing countries, there are far stricter rules governing women's sexuality. In most of Asia, under 10 per cent of women younger than 20 have had sex outside marriage. In Britain and Germany, it is 70 per cent.

All over Latin America, women usually wait till they are over 18 for sex. For men, it is closer to 16. In some countries, such as Peru, statisticians claim men are losing their virginity three years earlier than women, which begs the question of who they are losing it to.

In stark contrast, women in Africa start having sex many years earlier than men. Throughout much of West Africa - including Mali, Niger and Guinea - women lose their virginity at 15 on average; in most of the rest of sub-Saharan Africa, it is 16. For men, it's usually a couple of years later.

These age differences are reflected in attitudes to marriage partners. Zambia and Nigeria are two of the most ageist countries in the world, with men looking for wives who are more than six years younger than themselves. In most of Europe, and North America, men look for wives who are less than two years younger than themselves.

The Atlas of Human Sexual Behaviour also grimly reveals the darker side - and dismal consequences - of sex.

Britain has more teenage abortions than any other county in Western Europe, with 20 per 1,000 women aged 15 to 19 having abortions every year, compared with two per thousand in Germany. In many other countries, the figure is far higher, with 45 per 1,000 teenage girls in Bulgaria having abortions every year.

It is not only teenagers who are unable to control their fertility. Worldwide, 300 million couples have no access to family planning. In Africa, less than 10 per cent of married women are using a modern form of contraception.

The lack of contraception is starkly reflected in the number of babies that women have. The average number of births per woman is under two everywhere, except Africa, Middle East and South Asia.

But, by a large margin, it is African women who have the largest families. They start young, with more than 10 per cent of teenage girls giving birth in Africa each year. In Guinea, one in four girls aged 15 to 19 gives birth every year.

By the time they have finished, women in almost all Africa countries have had more than five babies each. In Niger, they have eight babies each.

The lack of safe contraception is also reflected in the epidemic of sexually transmitted diseases, particularly Aids. Across the world, 18.4 million people live with Aids, but Africa is by far the worst hit continent. In all of southern Africa, more than 10 per cent of people are HIV positive. In contrast, Europe - with years of safe sex campaigns - has ended up the most Aids-free area of the world outside Central Asia and the Middle East. In Britain, fewer than 0.1 per cent of people are infected.

Sex has also become one of the world's largest industries. In Thailand, the sex industry is worth $25 billion a year, employing 200,000 child prostitutes. But that total is dwarfed by the US, with 300,000 child prostitutes, and Brazil, with 600,000.

British

World's highest number of unmarried teenage pregnancies. Average life includes sex 2,580 times with five partners. More stamina (21 mins), and more women under 20 who have extra marital sex, than rest of Europe.

Thais

Lose virginity very late (over 20 for women) quickest lovers in the world (10 mins). Less than 10 per cent of women under 20 have sex outside marriage while 90 per cent of Thai men have sex before marriage. Highest rate of condom usage in the world.

Americans

Into cyber sex - biggest users of online pornography. Americans ask for dates via email as much as face to face. Only country where the average age for virginity is rising. Longest sex sessions in the developed world (28 mins) and also the most sex in the developed world at over 130 times a year.

Brazilians

Make love for longer than anyone else (a worldbeating 30 mins). More partners in the last year than anyone else on the planet, and consequently more tolerant of infidelity than anywhere else in the world.

Nigerians

Less than 10 per cent of women use modern contraception. On average, each woman has more than six children. One in five teenage girls has a baby each year. Up to 5 per cent of them have Aids. Women lose their virginity young, with Nigerian men generally seeking wives who are more than six years younger.

Italians

These shy sexual pandas lose their virginity later than anyone else in Europe (19 for men, 20 for women), have less sex than anyone in Europe (less than 100 times a year), and have quickest sex in Europe (14 mins).

 'The Penguin Atlas of Human Sexual Behaviour' is published on 3 July at £12.99

anthony.browne@observer.co.uk