Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
I suspect that journal editors could be reluctant to seek out early-career scientists as peer reviewers (see M. Casado Nature 560, 307; 2018). Researchers at this stage are often invisible to editors, because they have no publications or online research profile. Senior scientists, who have the grounding and scope necessary for in-depth peer review, are seen as a safer bet. In my experience, however, training graduate students in the critical assessment of research papers goes a long way towards equipping them for the task.