Last Night's Television - Lost Kingdoms of Africa, BBC4; Shameless, Channel 4; Too Old To Be A Mum? BBC1

Age cannot wither them

Too Old to Be a Mum? contained an argument just like a Möbius strip. Your mind ran along it, convinced that there must be another side somewhere and then just ended up where it started, having turned in on itself somewhere in the middle so that there was a kink in it, like one of those reversed loops in a telephone cord that you can't figure out how to get rid of. "Had I not done what I did," said Lauren, defending her decision to have twins at the age of 60, "they wouldn't exist and most people don't end up thinking, 'Gee, I wish I didn't exist'." In other words – and I'm not at all convinced I can accurately paraphrase her pretzel logic – her children's existence is categorically justified by her children's existence, which only exists (try and stay with me here) because she selflessly brought it into existence. There might be, of course, a lot of rebukes that would fall short of that traditional teenage cry "I wish I'd never been born". But though Lauren had considered some of those (her children's embarrassment, their potential early bereavement etc), none of them had trumped this strange inverted justification, essentially taking the form of a traditional parental cry: "One day you'll thank me!"

Lauren's argument was very weak, but the interesting thing about this account of mothers who look like grannies was that most of the arguments against what they'd done turned out to be a bit feeble too. There are those, for example, who accuse women like Sue, who had given birth to her daughter Freya at the age of 57, of selfishness. Her burning desire for a child, the argument ran, had been put ahead of the child's own long-term welfare. But if selfishness or parental desire were to rule out pregnancies the world would soon be depopulated. All parents – barring the accidental kind – are motivated by their own happiness when they have a child. We like to talk of it as "giving life", conveniently forgetting that there is no one there to receive the gift except us. And the suggestion that these mothers might be too old or infirm to give their children proper maternal love also seemed a little wobbly on reflection. It was true that both Lauren and Sue had a long catalogue of age-related afflictions, but it's hard to see why that alone should disqualify them from motherhood. We don't say that people in wheelchairs should be prevented from getting pregnant. And if you're going to cite what's "natural" as a demarcation you'd better have an argument ready for those who want childhood leukaemia to run its "natural" course. The kicker here was that all these mothers (even Rajo Devi, the 70-year-old Indian woman who really tested the elasticity of one's liberalism) appeared to be loving and caring, which is something that quite a few 20-year-old parents struggle to achieve.

They looked to have better life chances, anyway, than the baby born on the floor of the Jockey pub on the Chatsworth estate, ushered into a birthright of giro cheques and parental neglect. Shameless is back for its seventh series – Hogarth's Gin Lane without the moral disapproval – and Frank was looking for a little love. He found it in the very unlikely shape of an amorous librarian, who could apparently see past Frank's ratty hair and indolence stubble to the Byronic hero inside. Frank remains a great creation, but Shameless itself doesn't always seem very certain why it still exists; whenever it can't work out how to get out of a scene, it just has one character head-butt another, which it's hard not to read as a kind of habitual tic. I did like Frank's reply to his lover's inquiry about whether he believed in destiny, though: "Well," he said groggily, "I'm more a random-sequence-of-events man, meself".

In the last of Lost Kingdoms of Africa, Guy Casely-Hayford travelled around west Africa inspecting the relics of the once great trading empires of the region. In the case of Benin, a power in the land in the 16th century, most of these are in the British Museum, having been looted after a punitive expedition in the 19th century. And in the case of Jenné-Jeno, site of one of the oldest cities in Africa, there's not much left at all – mud architecture have a tendency to melt back into the ground once the civilisation that maintained it has gone. But everywhere he went Casely-Hayford also discovered a kind of living archaeology – very ancient traditions living on in the craftsmen and creators of today, sometimes with a disconcerting modern twist. In Benin, he watched bronze casters making a lost wax sculpture in just the way that their predecessors would have done 400 years ago. But I suspect their predecessors weren't melting down old car aerials and bathroom taps to create their works of art.