There are good reasons why there should be more postdoctoral students on temporary contracts in the physical and biological sciences than in the arts and social sciences. Modern scientific research relies on large teams working on specific projects with time-limited funding. To offer permanent posts to every aspiring academic would break the bank at research-led universities. But the scale of the discrepancies in job prospects suggests that there is more to it than contrasting research practices.
Part of the explanation lies in the popularity of the arts and social sciences at undergraduate level, which has fuelled demand for academic posts. Another important factor, however, has been the proactive approach of the Economic and Social Research Council. Not only are postdocs able to apply for grants in their own right, rather than under the patronage of a more senior academic, but the ESRC's distinctive fellowship scheme has given a start to many promising young academics. European Union regulations will come to the aid of many in the army of science postdocs, but their research councils might also take a leaf out of the ESRC's book.