Attenborough takes on reptiles in Life in Cold Blood

Now, the first thing everyone on television tells you about snakes is that they're not slimy and cold. In fact, they're silky and soft and cuddly and shyly flirtatious, have a dry wit and are good with children and old people. Oddly, if you ever visit a country where large poisonous snakes visit the natives, you'll notice the indigenous humans are invariably terrified into screaming abdabs by the mere mention of them, and simply can't kill them fast enough. Attenborough has done more than anyone to bring the natural world to those of us who quite sensibly live as far away from it as possible. The people who live next to it tend to see nature as a competitor, a predator, a nuisance or lunch.

Attenborough tells us reptiles can be surprisingly tender, and not in the cooked sense. He showed us turtles stroking each other's faces and crocodiles blowing bubbles at their mates through their noses. Granting these creatures feelings and moti-vations plucked from the canon of human philosophy, theology and Victorian fiction gives the audience permission to feel empathy and, after that, higgledy-piggledy feelings of guilt, responsibility, affection and fraternity. Television gives nature a narrative, a plot, that is wholly human; a belief that it contains episodic outcomes, happy endings and just deserts. But nature has no plot. There is no grand design and, most important, no right way for the world to be, no delicate balance.

There is nothing wrong with anthropomorphism. I don't believe we can look at nature in any other way. We can't disengage our own nature, which is to ascribe patterns to the world. And how could anyone devote their life to a cause, the way Attenborough has devoted his to the crawling, soaring and swimming, without being besotted and partisan? But, having allocated empathy to animals, we don't allow the same justification to Brazilian peasantfarmers or African hunters/ poachers. We make nature human, but exclude humans from nature. Crocodiles don't need to be awarded tenderness to make them better crocodiles.

The long Life on Earth series has shown us some of the most memorable and repeatable images ever made. And, as he gets older, Attenborough seems to be ever more awestruck by it all. The gift he has really given us over all these years is that nature is the great metaphor. In the end, the animal you remember most is the one human who goes through all the series, who's always there, lying behind some bit of wonder. It is his humanity that remains the great lesson.

Life in Cold Blood is a co-production with Animal Planet, a provider of easy-watching furriness for the club-class entertainment selection. They don't like unnecessary violence or unChristian sex. Why is our national broadcaster throwing its lot in with this American station and squandering the corporation's dwindling preeminence on a competitor?

Natural World (Friday, BBC2), about dolphins, was a more typical Animal Planet co-production, a tediously thin and poorly made piece of sensational and gullible exploitation purporting to show that dolphins will go out of their way to protect endangered swimmers from naughty sharks. We were shown this with an endlessly unilluminating reconstruction of an ugly family of New Zealanders treading water and trying to look concerned. Various experts from universities I've never heard of were brought on to explain that dolphins look after us because they have bigger brains than we do, and are generally nicer.

The zoomorphic lesson was that we should all live to be more like dolphins ourselves, because, hey, no dolphin has ever shot anyone or dropped litter; their carbon footprint is zero; dolphins don't fart in bed or forget to phone you the next day; no dolphin has ever been a hit-and-run driver, abused children or posed for Playboy. Look, frankly, we'd be better off if dolphins ran social services and utility helplines. There is, though, a heretical explanation to the odd behaviour of a dolphin apparently swimming round and round people when there are sharks about. They are actually the great white's bitches, and are drawing attention to this tasty snack so the shark can first chop it up into dolphin-mouth-sized chunks. There is another truth about dolphins that is rarely mentioned on Animal Planet - that they quite commonly creep up behind people in wetsuits and try to rape them. Let me tell you, an aroused male dolphin can make your eyes water.

I was never a great fan of Life on Mars. It was always too knowingly boorish and camp, with too much unnecessary HG Wellsish format and too little story. The scripts had their tongues so deeply in their cheeks, they barely made sense. However, John Simm and Philip Glenister both gave broadly watchable performances, and I know it's one of those rare TV shows that boys thought was actually made for them. The sequel, Ashes to Ashes (Thursday, BBC1), has moved up to the 1980s - to the squealing joy, I expect, of the prop-finders - and the departed Simm has been replaced by a woman. Why? Why take one of the few robustly male bits of evening TV and gratuitously cast a girl to femme it up?

DI Alex Drake comes on as a cross between a Charlie's Angel and Superintendent Jane Tennison. Keeley Hawes couldn't arrest an audience if she came on naked with a "This Way Up" sticker on her bottom. She's like a character that has escaped from a Depeche Mode video. Physically, she moved with all the sinuous martial confidence of room service, and she does emotion by breathing hard. The angrier she got, the more she huffed and puffed. But, most unfortunately, when she was on screen with Gene Hunt, she simply disappeared completely. You kept looking, but you couldn't see her. I expect there's going to be some sort of romance cooked up between them. Sadly, it looks like it will be onanism for poor Gene.