Is population spiralling out of control, or is growth levelling off? Either way, do we have the resources to maintain the human race?

We can breathe a sigh of relief that as 2022 arrived we weren’t reduced to converting the dead to tasty Soylent Green. When filmed in the early 1970s, the writers who penned the line “Soylent Green is people” doubtless considered half a century far enough away to make audiences believe the world could react to overcrowding and overstretched resources by recycling the elderly into food.

Science-fiction writers of the late 1960s seemed obsessed with population growth in novels like Harry Harrison’s Make Room! Make Room! – on which Soylent Green was based – and Stand on Zanzibar by John Brunner. They were inspired by scientists’ concerns about the pace of population growth at the time.

The estimated seven billion people in the world of Harrison’s Make Room! Make Room! or even the 40 billion of its movie adaptation fell short of an apocalyptic projection made...