Maths and education departments are becoming increasingly grey-haired as universities struggle to entice young staff on to their academic teams, a report shows.
The research councils last week published an analysis of staffing levels in higher education. The report reveals that the proportion of permanent academic staff aged over 50 has risen steadily, climbing from 35 per cent in 1995-96 to 41 per cent in 2003-04.
Mathematical sciences and education topped the league for ageing staff, with half of all permanent academics over 50.
Other subjects that are becoming increasing elderly included agriculture, architecture, business, chemistry, engineering, languages and physics.
The research councils have warned that poor career structure may be pushing young academics away and that "substantial effort" is required to address the problem in universities.
They add that universities face strong competition from private-sector companies, which are keen to lure the best young researchers away from academia.
Ian Diamond, chair of the Research Councils UK strategy group, said: "Shortages of talented researchers in key areas present a serious drag on the competitiveness of the UK research base. For example, the Diamond Light Source, a £500 million project in Oxfordshire, has faced major problems in recruiting skilled engineers."
The proportion of academics aged under 35 has dipped across the board since 1995, according to the report.
The analysis shows that education and physics departments are struggling most to attract younger staff: only 5 per cent of physicists and 6 per cent of education academics were under 35 in 2003-04. Computer science, law and the other physical sciences had experienced the greatest fall in numbers of young staff in the period 1995-96 to 2003-04.
The overall picture of recruitment in higher education is positive, with the number of academic and technical staff increasing 15 per cent over the nine-year period.
But some disciplines have experienced serious troughs. Numbers have fallen in architecture, chemistry, engineering, maths, physics and veterinary sciences.
Yet some subjects are blooming. Librarianship and information sciences experienced growth of 105 per cent. This was followed by subjects allied to medicine, whose numbers increased by 73 per cent.