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Luis Amarel, Boston University
"There are some individuals that have up to 800 partners"
 real 28k

Wednesday, 20 June, 2001, 18:05 GMT 19:05 UK
Sex degrees of separation

It is a small world when it comes to lovers, according to a Swedish survey of human sexual behaviour.

On account of the relatively few people who get to know an unusually large number of sex partners, many people are more intimately linked than they may care to imagine.

Kissing couple
You don't know where they've been
And it is these sexually hyper-active individuals that should be targeted in safe sex campaigns, say researchers at Stockholm University, as the consequences are likely to be more widespread should they contract a sexually transmitted disease.

Diseases such as chlamydia, gonorrhoea and HIV infections are on the increase worldwide.

Last year, there were 36 million people living with HIV or Aids across the world - 50% more than the World Health Organization predicted in 1991.

Earlier this month, the UK announced that the number of HIV infections is growing at the fastest rate yet. And American researchers released a study suggesting that one in five teenagers has an undiagnosed sexually-transmitted disease.

Footloose and fancy-free

Frederik Liljeros and his colleagues at the university questioned 2,810 Swedes aged between 18 and 74 about their sexual behaviour.

After applying a mathematical model to the results, they found that those with the most sexual partners act as the node - or centre - of a web of human contact.

These networks are highly susceptible to the behaviour of the best-connected "nodes", such as whether they use a condom when having sex.

The research is published in the journal Nature.

Six degrees of copulation

The research echoes the concept of six degrees of separation, the theory first posed in John Guare's play of the same name that everyone in the world is just six acquaintances away from anyone else.

Kevin Bacon
Kevin Bacon inspired a party game linking actors
It has since been used in the film trivia game Six Degrees of Kevin Bacon, in which players try to link any actor, living or dead, to the Footloose actor within six films.

Thus Oscar-winner Dame Judi Dench can be linked to Bacon in just two easy steps, even though the pair have never coupled on celluloid.

She played M in The World Is Not Enough with Denise Richards, who appeared in Wild Things with Bacon.

Now, just apply the same principle to your personal life...

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See also:

12 Apr 00 | Health
Safe sex message 'lost'
04 Jun 01 | Health
Aids: 20 years on
19 Jun 01 | Health
Virus peril of changing partners
13 Jun 01 | Health
Teenage toll of sex disease
07 Dec 00 | Health
Sex diseases on the increase
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