It promises to be a gruelling few weeks - and not just for the 16 contestants marooned on Pulau Tiga island in the South Seas for ITV's Survivor, which started on Monday.

The US version of the show last year produced truly staggering ratings.

The final episode was watched by 51 million people, 41% of the American viewing public.

ITV is hoping for a similar ratings bonanza for the much-hyped centrepiece of its summer schedules - and Survivor's audience will almost certainly come at the expense of a BBC 1 already battered by periodic assaults from Who Wants to be a Millionaire.

Survivor: Zoe

Not only that, but at the end of this week Channel 4 launches the second series of Big Brother.

Such "water-cooler" competition promises to make it a long hard summer for the BBC's schedulers.

Everywhere you turn it seems "real people" are popping up on television in shows that combine competition and confinement, humiliation and voyeurism in varying degrees.

A few years ago you could not move on British television for docusoaps - compelling and cost-effective slices of real life which offered many of the same attractions as conventional soap opera without the effort and expense of scripts or actors.

Survivor: Mick

The current rash of reality TV shows, from gameshows like Millionaire and The Weakest Link and Channel 5's new Jerry Springer-hosted Greed through Big Brother to Popstars and Survivor - have something in common with docusoaps.

But many are not cheap: Survivor is reported to have cost anywhere from �7m to �10m.

Many offer big cash prizes. Only Millionaire has found a way actually to make money - its prize fund represents the revenue from premium rate phone calls from would-be participants.

And while docusoaps were a peculiarly British phenomenon, reality shows have circled the globe.

Popstars was an Australian format. Millionaire and Link are British.

Big Brother is Dutch and has succeeded in provoking massive interest (and frequently outrage) in every country in Europe.

Big Brother's Nick Bateman: On the slide?

Survivor too was originally British - invented by Charlie Parsons of Planet 24.

But he could not find a British broadcaster to take the show on.

In the end the Swedes produced the first version, under the title Expedition Robinson.

With Survivor we in the UK have now seen all of the really original reality TV formats.

So far as one can tell, most of the rest now showing around the world are merely variants of those we have already encountered.

Reality TV still has a lot of life left in it yet, but the genre may have peaked.

Like the docusoap it may soon be history.

If you reckon you know what the next phenomenon to sweep the world of popular TV is, you could become very rich - and the BBC's schedulers would very much like to hear from you.

Nick Higham welcomes your comments at [email protected], although he cannot always answer individual e-mails.