Talk of fending off the ravages of age is perhaps no surprise when coming from two ageing presidents, both 72, neither of whom has expressed any interest in stepping down. What Russia’s Vladimir Putin and China’s Xi Jinping may not have known as they discussed human longevity at a military parade on Wednesday, was that their private exchange was being captured on a live news video feed – which Chinese officials say was viewed 1.9 billion times online and by more than 400 million on TV. The red-carpet conversation soon made headlines around the world, leading observers to debate whether Putin and Xi’s musings on “living to 150” were mere banter by autocrats eager to cling to power, or whether they might actually be onto something. Putin’s obsession with ageing Xi appeared to be the first to touch on the subject, telling his Russian counterpart: “In the past, it used to be rare for someone to be older than 70 and these days they say that at 70 one’s still a child.” To which Putin replied that thanks to developments in biotechnology, “human organs can be continuously transplanted, people could get younger as they grow older, and may even become immortal". Such statements could easily have come from the Silicon Valley, where American tech gurus have long shared the Russian leader’s obsession with ageing and immortality. “Putin takes his health very seriously,” says Stephen Hall, a specialist in Russian politics at the University of Bath. “It is said that his personal doctors accompany him on most of his appointments and trips and that a hospital in Russia is specially equipped to accommodate the Russian president at all times.” Russian official media typically heap praise on the “exceptional” health and longevity of the strongman in the Kremlin, who has served as either prime minister or president of Russia for over a quarter of a century.