Last Night's TV: Shooting Stars/BBC2<br />Horizon/BBC2

When the Shooting Stars pilot was broadcast in 1993 – fully 18 years ago now, the same year that Goodnight Sweetheart and Supermarket Sweep with Dale Winton appeared on our screens – it was shockingly fresh, a jolt of anarchic joy unlike anything else on television. The pleasures that Vic Reeves and Bob Mortimer guaranteed relied slightly on the fact that they made you a little nervous. As they propelled a stuffed black bear at Mark Lamarr, challenging him to stay put on his podium for a £5 prize, you laughed a lot, but you weren't sure if there was a more sophisticated joke going on than you had realised. Most of the time, there wasn't, except for the overarching joke behind the whole thing: celebrities are total idiots, and if you're watching one cleaning dandruff off a car windscreen with her bottom, you probably are one too.

These days, Vic and Bob are part of the establishment. As Shooting Stars returns for its eighth series – there have been breaks of varying lengths along the way – you could be forgiven for assuming the format would be a little tired, the surrealist approach a little dated, Ulrika Jonsson's ditz act a little hackneyed. In fact, though, while the show lacks the edge that it had in its glory years, and even though I kept thinking how wonderful it would be to be watching it for the first time, it remains one of the funniest things on TV. In a curious way, the national treasure status that the duo now enjoy makes it still more pleasurable – soothing, somehow, as well as anarchic. It's like visiting a kindly maiden aunt and finding she can still play the banjo with her toes.

Ulrika and her fellow team captain, Jack Dee, barely speak in this first episode. More than ever, it feels like, the show revolves around the supreme talents of its hosts (with an honourable mention for scorekeeper Angelos Epithemiou), and there's something wonderful about seeing the two of them still working so hard. Instead of cashing out and making a series of soul-destroying insurance ads, they spend their days coming up with jokes: lots and lots and lots of them, mostly nonsensical, nearly always irresistible. Bob drills a hole in Vic's skull through which the milkshake he subsequently drinks spurts at high speed. A creepy old man in a vest sneaks up on Brigitte Nielsen as lecherous Vic poses alongside her for a photograph. Bob asks James Martin, television chef and patsy-in-chief, if it's true he has a nightclub called Yorkshire Puddings where he only lets fat lasses in.

By the end, as Martin was forced to squat over a series of tin cans, depositing cocktail sausages that his tormentors were slipping down the back of his shirt, I was almost deliriously happy – not just amused, but happy – and keenly aware of the paucity of energy to be found in most of the more conventional examples of this genre. The irony is, Shooting Stars might have been on for 18 years, but it still feels livelier than rivals that are only just starting out.

Less chaotic but still more venerable, Horizon also returned to BBC2 last night, chalking up its 48th season and 1,085th episode. Last night's instalment looked at the science behind our perception of colour, which sounds like it might be a bit dry but turned out to be a fairly bamboozling tour through some fundamental questions that are as philosophically arresting as they are scientifically. If we could swap eyes (and brains) for the day, would you and I recognise each other's world? Is your cheery red postbox the same shade as my lush green grass?

That question was not definitively resolved by the end of the programme; very few were. But we were left with plenty of unsettling observations. "Colour doesn't exist. It is a construct of your brain," said Beau Lotto, the scientist we see the most of, casually dispensing with my entire belief system. "There is nothing literal about colour in the world."

Indeed, the relationship between reality and the version of it that our brain constructs is so tenuous that it can even be disrupted by language. In the most remarkable segment of an intriguing hour, another researcher visited the Himba people, in northern Namibia. Because their word for a set of dark colours takes in red and blue and green and purple, they have a much harder time distinguishing between two of those shades in an experiment, just as we are unable to tell the difference between two that look quite distinct to them. Which made my brain melt just as much as Shooting Stars did, albeit in a different way.