Hamish McRae: Why Charles Darwin offers a lesson for those hoping to survive in the media jungle

It is very easy to see why Michael Grade should wish to leave the BBC for ITV. It is a more interesting and more demanding job and it will be vastly better paid.

It is more interesting because ITV needs to be rescued and there are only three or four people who could reliably do so; Michael Grade is one of them, probably the best. It is more demanding partly because turnarounds are always demanding but also because the BBC chairmanship job is in effect being downgraded when the new trust structure starts in January. As for the more money, well, the commercial world is engaged in a global fight for talent and paying people decently is one weapon, though by no means the only one, that you use to attract it.

So that is that. What is much more interesting is how these two UK-based media champions can best exploit the opportunities available to them in a world where the power of incumbent TV networks is waning fast. Brand still matters - there is the BBC's greatest strength. Competence still matters - I am afraid that has been a bit of a weakness at ITV but that is fixable. And there is still great value in incumbency, partly because technology is moving very fast and we don't quite know how people will respond to the new possibilities.

It is worst than that. Not only do we not know what people want; we can only really find out by trying something and seeing whether the punters line up to buy it. Contrast video phones with YouTube. Hundreds of millions have been spent over the past 30 years trying to develop successful video telephone capacity but these have never been a commercial success. Then along comes YouTube, using what is now conventional if clunky technology, and lo, a billion-dollar business is created.

It does not matter that most of the stuff on YouTube is hopelessly amateur. At the Future of TV Conference in New York a few days ago the head of CBS Vision said: "You have to go through a lot of crap on YouTube to get anything good"; a comment that provoked the sarky retort from PC Magazine: "Have you watched CBS lately?"

In the world of YouTube low production values are almost a virtue. You expect dross; fishing out the nuggets is part of the fun. Indeed "new TV" is as different from "old TV" as fast food is from a three-course meal.

Think about it. The present model is that people watch television in a fixed place and they watch it, usually or at least frequently, with other people. There is a modification to that model, which is that they flick on a video clip on their laptop or their home computer when they log on to check the news or their e-mails. But that is still a fixed activity. Now there is a new model. It is so new that we don't know exactly what it will be, but it might, for example, be watching a two-minute clip on the mobile while waiting for a bus.

Earlier this month Nokia published the results of a report it had commissioned from the London School of Economics, called This Box was Made for Walking. The author, Dr Shani Orgad, reckoned that mobile TV would be a mixture of original programmes from the mainstream broadcasters, plus content specifically created for mobiles, plus self-generated content. New programme formats would emerge, including more talking heads and close-ups, episodes that would be chopped up into smaller portions, more "snackable" content, more user-generated stuff and so on.

What we don't know, though, will be the balance of use between the set meal and the snack. We know time is finite and we know that watching television is very time consuming. We know too that one of the reasons why the mobile phone boom has run so hot and strong has been that mobiles use "dead" time, time that would otherwise be wasted. By contrast, time spent at home on the computer is time not spent watching TV. So mobiles, unlike the home computer, increase the time available to watch the stuff that the Beeb and ITV might provide. But until we can get something close to television-quality video on our laptops and scaled-down TV-quality on our mobiles we won't know how we will allocate time between the different boxes available.

What I think is beyond dispute is that the stuff watched on a computer or on a mobile will be different from the stuff watched on a conventional TV. I think it is also beyond dispute that there will be some retreat from watching conventional TV. A rising proportion of UK households, particularly at the top end of the market, rarely or never watches it.

So the challenge to the incumbents all over the world, including the BBC and ITV, is whether they can create appropriate content for the new media.

At this stage there should be an accolade for the BBC. Of all the world's great media groups it has made as good a fist at adapting to the new media as any, maybe the best of all. The website is outstanding and neat ideas such as enabling you to listen to the Today programme interview on the web (useful if you are staying in the US) are clever packaging of their product. It is an inherently tech-savvy operation: Google "future of TV" and the BBC references cluster at the top of the list.

That matters as justification for the licence fee. I was talking to someone at the top of the BBC the other day and rather cheekily told him that I had not watched television except in the office, foreign hotels and the Heathrow Express for at least a year. His response was that for someone like myself, the website plus Radio Four would probably be worth the fee - and I had to agree with him. The big point here is that getting its footprint in the new media right is obviously a great opportunity for ITV. My impression is that the world is crying out for English-language content that is not American. That is why the new Al Jazeera English language service is so important. It fills a gap. The rest of the English-speaking non-American world has to rise to this challenge, and ITV ought to be in there along with the principal broadcasters in Canada, Australia, India, Singapore and so on. At the moment ITV may be fighting to defend an endangered perimeter. But it is a big brand; it has a wonderful set of mini-brands in its archive; and it has a lot of talent to draw from in the UK media pool. Now it will have someone in charge who understands how to get all this across, using the new channels available to it.

Or at least I reckon he has as good a shot as any, for I don't think any of the conventional media can understand the scale of change that is upon us. Our mantra should be that insight from Charles Darwin: "It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change."

Quite how you apply that is another matter. Still, in filching Michael Grade from his perch at the BBC, ITV has shown a certain adaptability, and those of us in other media, including the BBC, should wish him a tailwind.