The contrast could not be greater. Julie Overbaugh, a lab head at the Fred Hutchinson Cancer Research Center in Seattle, Washington, who researches the molecular virology of HIV, advocates the need for labs that allow their researchers a fulfilling life outside the lab (page 27). Conversely, Alfredo Quiñones-Hinojosa, a stem-cell neurologist and surgeon who heads the brain-tumour programme at Johns Hopkins University in Baltimore, Maryland, drives himself and his lab members as close to a 24/7 working life as is humanly possible (page 20). What might a young scientist make of these two styles, apart from the observation that it takes all sorts?

The necessity for hard work in science has long been emphasized. In his classic Advice to a Young Scientist, published in 1979, Peter Medawar emphasized the competitiveness of science and the inevitable concerns about priority. He also issued a golden rule: if you want to make important discoveries, choose an important problem. However, such problems add up to a recipe for perpetual hard work: important problems not only attract the most ambitious scientists but also present risks and false steps in the innovative approaches required to address them.

Overbaugh is right to highlight a need for time away from the bench or computer for creative reflection. Lab heads also need to ensure that their younger lab members maintain a sense of autonomy rather than of cog-in-the-machine. And young scientists applying for posts must understand what sort of lab head they are dealing with. But many older folk wistfully recall their early postdoc careers, when they had one or two clear challenges to focus on late into the night, and over weekends too. As research funding declines in many countries, science will intensify. Anyone lacking the inner intellectual drive and a capacity for relentless focus to get to the heart of the way the world works should stay away.