All four of the anonymous researchers asked to assess its merit were sceptical. But Berger and his colleagues were undeterred. Earlier this year, they published an updated version of their study, offering a deeper dive into the evidence they had gathered from the Rising Star cave system in South Africa. The approach paid off: two of the original reviewers agreed to reassess the science – and one was won over.
“You rarely see that in peer review,” says John Hawks at the University of Wisconsin-Madison, a member of Berger’s team.