It's conference season again and there will be more special sessions on 'women in science', which will no doubt be followed by another round of reports on the issue. The continuous examination of this subject can get tiring, but is of particular importance in the physical sciences, where the participation of women at all levels is unhealthily low. In the UK, only 5% of lecturers and professors are women — most of whom have been appointed in the last five years. Most women leave science well before they get to a senior position.

Science raises similar barriers to the advancement of women to the top level as other fields, such as the setbacks caused by taking career breaks to have children. But more importantly, the world of science, perhaps more than any other field, raises obstacles due to its system of peer appraisal and patronage. Science operates mainly on the perceptions of your work by your peers — not only those you share a lab with, but many other researchers, grant administrators and journal editors. For junior researchers, this perception is strongly influenced by whether or not you have a more senior scientist pushing you forward and promoting your interests. Having a scientific 'patron' or 'mentor' strongly improves your chances of obtaining a permanent university position, being a co-author on grant applications, getting invited talks at conferences, and engaging in productive collaborative research. This is a key area in which women are currently well behind the men.

Much depends on the attitude of senior academics — most of whom are male, and many began their careers when there simply weren't any women in science. Some feel that it is important that there is equal representation, and are effective mentors to both men and women. A significant minority, however, do not want to acknowledge that the lack of women in science is a problem. The dearth of women in senior positions means that many junior female researchers do not have the effective mentoring that would enable them access to the top levels. It's surely not an accident then that research groups in the physical sciences seem to fall into two categories — those with a good number of female scientists, and those with hardly any women at all.

Some European countries — notably Norway and the Netherlands — are trying to rectify this situation by instituting some form of 'positive discrimination' by funding fellowships and permanent university positions specifically for women. Many other countries, including the UK, are reluctant to follow this route. The main argument against it is that reserving certain positions for women would lead to a perception that women cannot get the job on merit. And, although these schemes are intended to increase the representation of women at the senior level, some of them seem a little misguided. In Norway, for example, there is a rule that there should be at least 40% of both men and women on university boards. This might sound good theoretically, but it means that because of their limited number, female staff members are often forced into taking these positions — and let's face it, being on a departmental committee is an administrative burden that has few rewards in the way of prestige and 'power'. It is far more important in terms of career progression for female scientists to be on grant-funding committees, conference-organising committees and journal editorial boards, where their representation is still very low.

It is rather unlikely that the culture of science — which often involves aggressive self-promotion and even taking credit for the work of others — is going to change. However, women in junior positions could be more proactive in terms of finding good 'mentors' or research supervisors. At a more senior level, women should put themselves forward as symposium organisers, referees for grant programs, and as members of journal editorial boards. These are the roles that get you visibility — and more importantly, encourage other women to enter, and persist with, scientific research.