Last Night's Television: Orangutan Diary, BBC2<br />Baroque! From St Peter's To St Paul's, BBC4

The titles for Orangutan Diary freeze on an image that is a perfect emblem of its seductive appeal: a small hairy hand clutching dependently at a human arm. That, at one level, is what primates mean to us, however big and muscular they become. We see them, thanks to a broad misreading of Darwin, as ourselves in infancy, and when they're brought into conjunction with human clothing or human objects, our familial (and faintly condescending fondness) is amplified. When the primates are actually infants, even the sternest rationalists are likely to find themselves melting into a puddle of anthropomorphic sentiment. Orangutan Diary contains images of such concentrated cuteness that they should probably read out one of those warning statements at the beginning, alerting particularly susceptible viewers that it contains "extreme scenes of winsomeness from the beginning". When they wheeled on a wheelbarrow full of baby orang-utans in disposable nappies, you could probably hear the audience reaction coming through the window, a strange collective moo of delight.

Whether this kind of thing is really good for orang-utans, I'm not sure. The ones in the rescue centre where the films are made seem to be in clover, lolling about in hammocks and throwing their hairy arms around their foster mothers. And since an orang-utan is mostly arms, with a small body and a pair of liquid eyes attached as an afterthought, a more physical embodiment of a fond embrace is hard to imagine. They are clinging neediness in a fur coat, and the refuge where Orangutan Diary is largely filmed oozes a reciprocal affection and tenderness. They even blow soap bubbles for the nursery class, with the babies following them through the air with just as much rapt wonder as any human infant. But given that people are the biggest threat to orang-utans in the wild, you couldn't help but wonder whether being taught to fear and distrust us might be more to the point. There were occasions, too, when you wondered whether there was a bit of wishful projection going on. Last night's episode ended with the colony's biggest orang-utan being taken off to a nearby island for a bit of R&R with the other adults. "It offers him a taste of the freedom and dignity that 16 years of captivity have denied," someone said. Or, possibly, a howling stretch of agoraphobic terror. The refuge's director chucklingly described him as a "beach bum", on account of the fact that he liked to loll around on the river bank. I think he may have been sitting there thinking, "When the hell are they coming back to get me?"

In Baroque! From St Peter's to St Paul's (the exclamation mark is significant), Waldemar Januszczak provided a simple visual aid to illustrate his subject. This is the Renaissance, he said, holding up a perfectly spherical pearl. And then he showed you a gnarled, lumpy pearl to illustrate the Baroque. That's where the word comes from, he explained, the Portuguese barocco, meaning misshapen pearl. And comparing the two – Platonic geometry against arbitrary curves and bumps – I think pretty much any viewer will have instantly got the point. Januszczak himself is one of television's lumpy pearls, and his approach to this subject was knowingly baroque, as in-your-face and intent on dazzle as the architecture and art he was describing.

Like Baroque works of art themselves, some of it struck you as excessive and a bit mad. There was a strange moment when he took issue with the standard line on Caravaggio. "Even sensible commentators on sensible TV channels," he said, "have insisted on seeing him as a knife-mad, predatory homosexual who went berserk in Baroque Rome... the ripper of Roma." But he didn't explain why this view of the painter's private life was inaccurate, and his own description of a Caravaggio canvas coming after you "like a spotlit rottweiler" hardly seemed to offer a model of unsensationalising connoisseurship by contrast. The truth is, you suspect, that he'd much rather be different and interesting than right and conventional, an instinct for belligerent contradiction that later led him – completely unconvincingly – to pooh-pooh the idea that Bernini's statue of St Teresa might contain a powerful erotic component.

He's never bland, though, and if you can live with having him in your face, he often effectively sidesteps the conventions of the upmarket art documentary. There are, for example, no cut-away graphics in the films. If a map is needed, Januszczak unfolds a reproduction of a famous Baroque map of Europe and jabs his finger at the relevant spot. And in a Borromini chapel, he unrolled a sheet of brown paper, kneeled on the floor and sketched out the essential floor plan with a felt-tip pen, the kind of simplification that would usually be consigned to computer animation and that would be the worse for it, because it would break contact with the presenter's wild flourishes of enthusiasm. You may turn off because it's all too baroque, but you're not likely to do it because you're bored.