It’s widely accepted that there is a logjam in the academic career stream. There are too many postdocs for too few faculty positions. The average age for achieving full independence is rising, and the postdoctoral period has gone from being a second apprenticeship to an indefinite stay in limbo. One proposed solution is contraceptive – that we should train fewer PhDs. It’s wrong.

It’s undeniable that scientific reproduction bears an eerie similarity to biological reproduction. Young scientists are produced in abundance, but only a very small number achieve permanent positions in academia. There are many seeds, and few survivors. A 2010 study commissioned by the Royal Society in the UK found that only 0.45% of PhDs go on to become tenured faculty. That’s better odds than being a sperm, but comparing yourself to semen is unlikely to boost self-esteem. Scientific reproduction therefore seems to be an extremely wasteful and inefficient strategy – wouldn’t it be more humane to limit numbers so that seed is not squandered fruitlessly?

It’s hard to argue with the logic. If the supply of young scientists outstrips the demand at a faculty level, then the easiest way to ease the pressure is to reduce the number of young scientists in the system. Fewer PhDs means fewer postdocs means fewer applicants for faculty positions, and thereby a depressurisation of the hypercompetitive atmosphere that has probably ceased to be a spur to productivity and is arguably now poisoning the research environment. Right?

Wrong. As with any piece of logical reasoning, the slip is in the assumptions – in this case, what PhDs do, and what they can do.

PhDs are not “just” postdocs or even group leaders in training. They are also the engines of university labs and research groups run by junior group leaders. Postdocs – with their higher expertise, generally higher competence, and higher salaries – are a luxury resource. Proposals to reduce the numbers of PhDs in the system generally seem to come from people working in a postdoc-rich environment where the supply can be taken for granted. It is important to remember that this is not the norm. The vast majority of scientific data is probably generated by predoctoral scientists.

Furthermore, the entire notion that reducing PhD numbers will solve the logjam is predicated on the notion that all PhDs should or will try to become postdocs. This would truly be an unfavourable outcome – there are vanishingly few opportunities for permanent positions at the postdoc level, and not all postdocs will be suited to step up to group leader positions with the extra responsibilities (not least in terms of mentorship) that this entails.

Instead, the critical thing is to ensure that instead of treating academia as a default career pathway, PhDs view it as one option among many. Young scientists are probably at their most employable immediately following the completion of their PhD, and the choice to remain in academia – and it should be viewed as a choice – is one that should be evaluated alongside a host of other options.

Group leaders may well be the worst people to ask for such career advice, because in most cases they won’t ever have worked outside academia. But it’s precisely the non-academic career options – in publishing, industry, administration, politics, outreach – where scientists are most needed. There is undeniably a glut of young scientists vying for faculty positions, but in many cases they may be doing so simply because they’ve never stopped and asked if they could be – or even, if they would be happier – doing something else.

We should be encouraging young scientists at every stage of the academic career ladder to be developing alternative career plans, not least because of the chronic and inherent uncertainty that that route brings.

In Woody Allen’s 1972 classic “Everything you always wanted to know about sex* (but were afraid to ask)”, the climactic scene – in every sense – features a crowd of anthropomorphic sperm preparing to take the plunge into the unknown. Allen, unsurprisingly playing a neurotic and rather pessimistic sperm, tremblingly confides that “sometimes the guys will slam their heads up against a wall of hard rubber”.

Like sperm, young scientists have the odds stacked against them. Putting additional barriers in place is not the answer. Young scientists also the ones needed to colonise other areas of science besides academia. The 21st century will be defined by science, technology, and way they interface with society. In such a future, we need more, not fewer scientists.