Last Night's TV - True Stories: Joan Rivers – a Piece of Work, More 4; The Ark, ITV1

Some painfully funny moments

You didn't have to be a fan of Joan Rivers to enjoy Ricki Stern's excellent documentary Joan Rivers – a Piece of Work. In fact, a bit of detachment would probably have made things easier, given how nakedly it exposed her insecurities and bitterness. Because, while this wasn't an unsympathetic film by any means, it wasn't in the business of flattery either. The opening frames – an extreme close-up of River's heavily worked face getting its first early-morning application of make-up – offered a kind of visual epigraph for an uncosmeticised portrait. At the beginning of the film you were inclined to give the credit to Joan Rivers herself for this, taking it as an extension of the say-anything, show-anything candour that underlines her comedy. By the end of the film you found yourself wondering whether she was simply powerless to resist the seduction of any camera lens, whatever it was going to reveal.

Stern had followed Rivers for a year, and not a particularly vintage one in terms of her own career. "I'll show you fear," she said near the beginning. "That's fear." And then she displayed an empty double-page spread in her day-planner. "One job a day is not enough," added her long-time manager Billy Sammeth, explaining how she would often put on sunglasses before flicking through her diary, in a running gag about the dazzle of its empty white spaces. She certainly doesn't seem to be one for resting on her laurels; there could never be enough of them for that, and even the most florid of them seem to prickle and irritate her. They have the wrong- shaped leaves, because they emphasise her age, or underplay her acting talent. The need isn't only psychological though: "This is how Marie Antoinette would have lived if she had had money," Rivers joked, standing in a Manhattan apartment that looked like a chintzy aircraft hangar. That takes upkeep, as does the sheaf of staff paychecks Rivers has to sign on a regular basis.

"I've definitely been through ups and downs with her," said one of those dependents, her personal assistant, Jocelyn, a kind of human resonance damper, who was there to even out the seismic shocks of Rivers's moods. There were more ups and downs to come, in a year that saw the Queen of Comedy signing on to the American version of Celebrity Apprentice ("I'm doing [it] because it's face time on NBC") and touring a play to the Edinburgh Festival and London, in the hope that she might finally lay the ghost of a wounding theatrical failure early in her career (she found the reviews so humiliating that she actually left New York for a time). Sadly, it wasn't to be. The play went down well in Edinburgh, but only tepidly in London, where Rivers was filmed waiting for her first-night entrance looking sick with anxiety. Instead of taking Broadway in triumph, Rivers had to settle for doing stand-up in Wisconsin (a venue that she seemed to regard as only one step up from hitting the comedy circuit in Chad) and winning Celebrity Apprentice, beating out a female poker player called Annie Duke who had earlier provoked her considerable powers of vituperation by being nasty to Rivers's daughter. Storming off set at the time, Rivers had instructed her assistant to post a Tweet for her: "Tell Annie Douche she can kiss my Jewish ass, but not with those big pig lips," he dictated. "You think that's too rough?" By the end of the film she was up again, but you'd been given a glimpse of a woman lashed to a treadmill, terrified that the one place where she feels genuinely happy – under stage lights – might one day be denied to her.

ITV, which has done very nicely for itself recently by betting big on quality drama, seems to be making little stirring motions in the direction of straight documentary too, with The Zoo, a three-part film about London Zoo. It's not a patch on Molly Dineen's four-part film, The Ark, which went out nearly 20 years ago but it had its moments even so. "You learn one thing early on – and that's never to look up with your mouth open," said a stoical man who was brushing out the monkey house, a piece of advice that is surely applicable to many other walks of life. The venue delivers some dependable, audience-pleasing content: poorly animals, cute behaviour and winsomeness. But it was really about the passion of the upright apes – keepers whose fascination with their charges often ignored the primal instincts. I particularly enjoyed Dave, who looks after the spiders and was seen here earning some extra income for the zoo by conducting a desensitisation course for arachnophobics. He had to do a careful inspection of the lecture hall before letting the customers in. "The last thing we want is a spider suddenly running out when we've got a room full of arachnophobics who haven't been cured yet," he explained drily. Like Joan Rivers's assistant you have to be able to take the downs with the ups. Dan, who'd given up a city trader's job to look after the primates, was almost as happy as if he was having a child himself when one of the gorillas got pregnant, but as tearful as if a close relative had died when the gorilla who'd done the impregnating succumbed to a mysterious illness. In a way, I suppose a close relative just had.