In Greg Duncan, the Society for Research in Child Development (SRCD) may have found the perfect person as president to lead an organisation where inter-disciplinary science is all-important.

In his presidential address on the penultimate day of the SRCD conference in Montreal last week, the economist said: “I know economists can drive developmental scientists crazy”, Duncan commented. “The lumping together of everything that is not IQ into a category called ‘non-cognitive’ skills is not a way to make friends in the psychology community!”

According to SRCD rules, every third president must come from outside psychology. Duncan is the third economist to lead SRCD. As he described in his address, his career has been a model of collaboration.
But he also made a compelling case for the place of good economics in the child development field.

He said: “A $3,000 a year increase in family income between birth and the fifth birthday would produce an increase in years of school completed of eight-tenths of a year. This would generate $10,000 or more of per year of earnings for these children.”

Duncan described the differential effects. Higher income later in the year provides fewer benefits. The same money would mean about 45 per cent of an extra year of schooling for children aged six to ten and just under a third of a year for High school students.

In the early days of the collaboration between economists and other child development sciences, Duncan noted, there were some curious disparities. For example, the adequacy [have added this as everyone has income but we are talking about how much] family income during childhood predicts educational outcomes but it does not predict the likelihood of criminal history. It does predict adult obesity but it does not predict the possibility of children born outside of marriage, but the size of income in the early years predicts adult hypertension and arthritis.

As Duncan demonstrated, these anomalies indicated the limits of economics in understanding developmental pathways.

In his many collaborations, Duncan has come to understand that early foetal stress, brain development, adolescent stress and the immune system are all playing their part. These mechanisms have been uncovered by multi-disciplinary teams.

Economics may be a blunt instrument for studying child well-being, but it also leads to blunt but effective policy interventions. Duncan told the audience that the increase in the Earned Income Tax Credit of $2,000 in the USA in the mid-1990s produced an increase in maths test scores of two standard deviations. This is a cheap price for legislators concerned about the future competitiveness of their nation.

Duncan left his audience with two metaphors from people to whom he has looked for inspiration in his career. The Nobel prize-winning biologist Francois Jacob has said that “novelties come from previously unseen association of old material. To create is to re-combine”.

The popular science writer Matt Ridley in his book The Rational Optimist talks about ideas having sex with other ideas. And ideas meeting, mixing, mating and mutating to drive the huge development of human society in the last 200 years.