How many scientists do we need?

South Africa is in urgent need of a large increase in the number of technically trained people, especially scientists and engineers. To determine an effective strategy to meet this need, it is useful to explore the structure of science, which is essentially that of a pyramid.

At the base are children in primary, secondary and high schools. Above them is a smaller number of university students—undergraduates and post-graduates.
At the peak are a few PhD scientists who do research and publish papers in peer-reviewed journals. (Sports have a similar structure, with professional athletes at the peak.) Which level of the pyramid contributes the most to the wealth of a country?

Some contend that the scientists at the peak are of most importance because their discoveries and patents can benefit everyone. In that case, poor countries should increase their number of PhDs and should encourage those scientists to do more research and to publish more papers that, in principle, increase our pool of knowledge.

Most of those papers, in reality, are of little value and receive scant attention from the scientific community. Progress in science, an undemocratic activity, depends mainly on the “vital few”. (The “law of the vital few” states that, in many activities, 80% of the effects come from 20% of the causes.) In poor countries, where education levels are low, we must guard against too big an increase in the number of over-educated scientists who write papers that are mostly of academic interest. Scientists should be encouraged to strengthen the base of the pyramid by getting involved with schools.

Phenomena such as Silicon Valley in California suggest that the students who become innovators and entrepreneurs are far more important than their professors. Hence the success of PhD scientists should be measured primarily in terms of the impact of the training they offer at universities and the success of their students—and secondarily in terms of their publications.

Is there an optimal number of PhD scientists for a country? The number of scientists in a country can obviously not exceed the total population. It is therefore intriguing that, for several centuries, in several countries, the number of scientists grew at an astonishingly rapid rate—far more rapidly than the human population. Starting in the mid-17th century, the number of scientists roughly doubled every 15 years, whereas the human population doubled roughly every 50 years.

Such a rapid growth in the number of scientists cannot continue indefinitely, so it is not surprising that, in some wealthy countries, the rate of growth has recently slowed down. Presumably an equilibrium will soon be reached, with the number of scientists growing at the same rate as the population as a whole.

What is surprising in the available data is a high correlation between the growth in the sciences and the humanities. Although the resources available to scientists have been increasing significantly, especially since World War II, universities have apparently diffused those resources, allowing all disciplines to grow at the same rate. This suggests the factor that has the strongest influence on the growth of disciplines, including the sciences, is the number of students enrolled at universities. (The number of mathematicians in a country is determined mainly by the number of students who have to take courses in calculus.)

In the rich countries, the very rapid growth in the number of scientists (and more generally PhDs) is slowing down because there is no longer a rapid growth in the fraction of the population attending universities. In future, the rapid growth of universities is likely to occur in poor countries, where, at present, a relatively small fraction of the population receives tertiary education.

Of all the students and learners, a tiny fraction will have exceptional scientific gifts. Hence the developing countries will produce an increasing fraction of the outstanding scientists of the next several generations. This, of course, can only happen if children in schools are provided with a good education, and if the gifted ones are identified and nurtured from an early age.

Up to the end of apartheid in 1994, South Africa had a strong scientific establishment based on only 10% of the population. The changes around that time, especially the emigration of large numbers of highly trained people, weakened science significantly but ushered in a new era with great potential because the pool of potential scientists increased enormously.

In 2007 the DNA pioneer and Nobel prize-winner James Watson drew widespread condemnation for suggesting that black people are less intelligent than their white counterparts. Until 1994 such sentiments informed education policies in South Africa. To overcome the enormous harm those policies did, South Africa has to make special efforts to build the self-confidence of its students. They have the ability and talent; to succeed they need encouragement and opportunities. The high rate at which students drop out of universities before they graduate suggests that students receive inadequate mentoring.

The long-term prospects for science in South Africa are exciting because the increase in the percentage of the population that attends universities over the next several decades implies a growing pool of students with exceptional talents for science. Their training requires an increase in the number of PhDs, the highest priority of which should be the teaching and mentoring of those students.

This is an abbreviated version of a paper that appeared in the South African Journal of Science. Professor S George Philander is research director of the Africa Centre for Climate and Earth Systems Science (Access). Website:

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