It’s a grey day in Berlin and 500 or so of the world’s pre-eminent ageing scientists and longevity enthusiasts (that is, wealthy people hoping for a few more years to spend it) are gathering to discuss how to live for ever, or at least a little longer. The atmosphere at the second annual Undoing Aging conference is one of nervous optimism.

Gerontology, the study of the biological processes that underpin ageing, is booming, thanks to scientific breakthroughs and a rush of funding from Silicon Valley. Amazon founder Jeff Bezos has invested in the field. So, too, has Facebook board member Peter Thiel. Google has its own gerontology start-up, Calico, armed with more than $1.5 billion (£1.1 billion) in funding. Finally, a treatment for delaying or