The sad death of Francis Crick at the end of last month rightly generated a number of tributes from his friends and colleagues. But as I read these words, I was struck by a surprising fact. Crick, the man who co-discovered the structure of DNA, did not begin work on his PhD until he was 35.

By today's standards, this is remarkably old. In France, if you have not achieved tenure by that age, your scientific career is considered by many to be over. In Germany, Habilitation — a process that requires PhD scientists to complete a second thesis and demonstrate their teaching abilities — means that many academics don't gain tenure until their forties, although reforms may change that. And in the United States, beginning a PhD at 35 would put you on track for tenure at the age of about 50.

Crick's career was slightly unusual — he had stints in the military and as an engineer before moving to the University of Cambridge. But his delayed entry into postgraduate studies should reassure others who would like to enter science later than is conventional. And it also points to ways in which ‘late-bloomers’ might reinvigorate the scientific workforce.

Encouraging people to begin a PhD after working in a different discipline or sector would create scientists who are more truly multidisciplinary. It would also provide an alternative pathway to the usual undergraduate–postgraduate–postdoc route that some young scientists find constraining. And targeted schemes to lure late-bloomers into labs may be one way to fill skill gaps that arise in a younger workforce that lacks training, education and experience.

Whatever the reason, it seems sensible to welcome skilled people who want to switch directions, rather than to impose barriers on them — and their potential breakthroughs.