Big Brother, Channel 4<br></br>Living With Monkeys: Tales From the Treetops, BBC1

As Davina says, the journey continues. But I'm starting to feel a bit travel sick

The apprentice has been hired, Britain has indeed got talent, and America has found its latest idol – where are we lovers of reality television to turn our gaze now? Why, to series 10 of the show that kick-started the genre, of course, as another bunch of hapless Big Brother housemates made their way over to Hertfordshire for three months of acting and interacting in the television equivalent of the Petri dish.

They entered the house to the now-predictable chorus of cheers and boos, but, even as Davina McCall was introducing them, there was a here-we-go-again feel to the whole affair. "What a journey it's been over the last 10 years, and tonight that journey continues," she intoned, breaking reality-TV's previous record by managing to squeeze the "J" word twice into her opening sentence.

As the 16 contestants preened and posed before finally progressing to the front door, even Davina – dressed in what appeared to be a designer Latex binbag – started to sound bored, her I'm-above-all-this commentary taking on a disconnected tone not heard on TV since Terry Wogan stopped doing the Eurovision Song Contest. And, increasingly, this is the position that Big Brother now finds itself in: a summer sideshow of ever-decreasing returns.

Still, there are contestants to be savoured, if for all the wrong reasons. There's Lisa, a lesbian who looks like Sonic the Hedgehog. Angel, who went in dressed like a Victorian undertaker and, as the first week progressed, started to look ever more in need of one. There are the blondes, distinguishable as yet only by their chest sizes; the single mum, who believed she could make her children's lives better by absenting herself for three months and then quit after eight days; the posh boy; the Muslim; the gay guy; and the hunk.

But there were also some rather less predictable choices: Marcus, who may look like Wolverine, but in reality resembles Bill Bailey impersonating David Brent; Sree, who may well be "a suitable boy" in southern India, where he grew up, but here looks increasingly like cannon fodder; and, best of all, Siavash, whose introductory video contained the immortal line, "You see all these, like, rock stars and celebrities and all that ... I do what those fuckers pretend to do."

And Big Brother of course had a twist up his sleeve – no one was an official housemate until they had earned the right. Cue two days of senseless tasks (Lord Freddie had to change his name to Halfwit, or Dipshit as one contestant prefers, while Lisa had to, er, answer the phone) before finally, poor Beinazir was put out of her misery and became the first contestant ever to be evicted by public vote before even getting the chance to live in the house.

As nominations approached, things started to get bitchy – not least in the Diary Room, where posh boy Freddie/Halfwit/Dipshit threatened to kick off another Big Brother race scandal by accusing Sree of having done nothing since he came into the house except "curry favour". In the end, it was Freddie himself and argumentative Sophia who were put up before the public vote. Who went? You decided. Or at least those of you still watching by Friday night did. Because what started as an interesting social experiment has now clearly become nothing more than a springboard to a Heat magazine cover and temporary free entry to dodgy nightclubs.

"It's fascinating to focus in on individuals and try to work out what their story is and what's going on," said primatologist Dr Julie Anderson as she and "adventurer" Guy Grieve settled into their treehouse for six weeks of watching the wildlife in the Congo basin of Gabon for BBC1's prime-time two-parter Living With Monkeys.

And while the creation of reality TV has undoubtedly found its illogical conclusion in shows such as My Monkey Baby, reviewed last week, it has also taken its toll on what used to pass for serious natural-history programming. Would Guy and Julie really become "a modern-day Tarzan and Jane" as the excruciating voiceover promised. Did we really need that same voiceover (one Matthew Rhys, hang your head) telling us, as the skies opened overhead, that "they don't call it the rainforest for nothing".

After two hours of such platitudes, it was difficult to care. Because the most interesting thing about Living With Monkeys was the (briefly shown) footage caught by cameraman Gavin Thurston's "jungle equivalent of CCTV" of the endangered red-capped mangabeys in action. Such pictures proved how captivating it can be to watch creatures caught unaware that their behaviour is being viewed and monitored. A fact the producers of Big Brother appear to have entirely forgotten.