Opinion: Perspective - Brands must adapt to thrive in new social networks.(Peter Friedman )

Peter Friedman says he is taking advertising back to its roots Which seems odd coming from someone who honed his marketing skills in Silicon Valley, admits to e-mailing his son even when they are in the house together and has you wondering if anything lighter than a crowbar could part him from his laptop.

Friedman is in London this week talking to agencies and clients in the wake of the newly announced joint venture between LiveWorld, the company he helped found and which has become one of the catalysts of the boom in social networking sites, and WPP.

Rest assured his sales pitch will have left many listeners wondering how to get a word in edgeways, such is its pace and passion. But Friedman, 51, who chose to join Apple rather than pursue his original aim of becoming a hotshot Madison Avenue manager, comes across as neither a nerd nor an anorak. And what he says merits serious consideration by agencies still trying to separate the communication superhighways of the future from the cul-de-sacs.

Are social network sites the way to go? Some believe the jury is still out. Friedman, whose company operates and manages such sites, considers the case is already proven beyond reasonable doubt. A seismic shift in consumer behaviour is taking place, he claims, and if brands are to flourish within it, they need to look to the past.

Consider how brands found fame in the days when advertising barely existed, he suggests. It was through word-of-mouth. Now technology, which for so long isolated people, is allowing that to happen again. That is down to the internet, now an essential part of the fabric of life for almost everyone.

For word-of-mouth, read 'virtual communities' often comprising millions of members empowered to confer huge benefits upon brands they like - and to inflict serious damage on those they do not.

Of course, it is easy to get swept along on the technological tide. Like Mark Twain's ...