The past week has seen an outpouring of online comment on the subject of sexual harassment in science and its satellite careers such as science journalism and communication. It was prompted by allegations against a leading figure in science blogging, Bora Zivkovic, who has since resigned as blogs editor with Scientific American (which is published by Nature Publishing Group).

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Much of the comment has been from women, a distressingly large number of whom have described their own experiences of misogyny and prejudice in the workplace. One lesson to be drawn is that language matters: in effect, there is no such thing as ‘casual’ or ‘low-level’ abuse. And, as the ongoing comments from both men and women on social media make clear, the impact of such behaviour on women, many of whom are early in their careers, can be pernicious and long-lasting. Women can begin to doubt their achievements and their abilities. They might question the motives of people who comment on their work. In short, they can lose confidence; when combined with the structural and institutional obstacles that they already face, this can make women look elsewhere for job satisfaction. This is unacceptable. Science simply cannot afford to lose some of its best talent to boorishness.

A major problem is the widespread tacit acceptance of adolescent behaviour. Let us call him Dr Inappropriate: he is the lecturer at the conference drinks reception with the wandering hands. (No such behaviour has been attributed to Zivkovic.) He is the head of department who thanks his female colleague for her excellent presentation but suggests that she wears a shorter skirt next time (yes, this really happened). Worse, Dr Inappropriate is often the lab head, or an equivalent — a mentor with responsibility and power over the careers of the women whom he asks to work late on a project or to join him in a taxi home. Sometimes he is a very senior scientist indeed.

Nature acknowledged in an Editorial last year that we have poor representation of women among reviewers and authors (see Nature 491, 495; 2012) — but we pledged to change and have attempted to do so, with mixed results that we shall report soon. We have asked others to acknowledge their own gender biases, and urged them to do what they can to improve the prospects and visibility of women in science.

Our Women in Science special issue this year (see offered our most comprehensive and high-profile collection of articles on the subject so far. Yet we have not adequately addressed the problem of harassment, perhaps because it is difficult to quantify. Officially, the obstacles to women in science are policy issues such as availability of childcare and lack of flexible hours. We might never know how many are pushed to leave because they are fed up of working with Dr Inappropriate. Just as worrying are those women who do not make that choice and who find that they must simply endure.

The evidence of the scale and depth of the problem is anecdotal. But the anecdotes all point to sexual harassment being a real stain on science. Just ask around: every­one knows a Dr Inappropriate. (We have here emphasized male–female harassment, but female–male and same-sex harassment happens too.)

Nature special: Women in science

What is to be done? Most institutions already have policies that outlaw harassment and bullying. Could and should they be more strictly enforced? Yes. This often requires the victim to make an official complaint, and many are justifiably reluctant to do so, but a facility for anonymous whistle-blowing may help. A more pragmatic solution is to force Dr Inappropriate to keep his hands to himself, and this is where the rest of us can come in. More of us must challenge such actions when we see them, publicly if necessary. Too often we accommodate and excuse them: “He doesn’t mean it”; “That’s what he’s like after a drink”; “Just make sure you don’t work late on your own.”

There are many behaviours that could be construed as abuse, and there are grey zones. Flirting is human nature. Some students marry their supervisors. Such considerations argue against glib judgements, but must not distract from the central message.

Here is one category of sexual harassment to focus on: when it represents an abuse of a professional relationship, particularly one in which the abuser has power and the victim feels unable to challenge it as they would like. That is wrong, and we should all label it so. We should all seek to promote not only appropriate rules, but also a culture of active discouragement and prevention of sexual harassment. If you are the party with the power, ask yourself: will the recipient of your social overtures wonder whether your support for his or her work is dependent on how she or he responds? If the answer is yes — or even maybe — do not cross that line.