How the Chinese one-child policy sprouted by chance at the UT

It is the spring of 1975 when Geert Jan Olsder – mathematician in the Twente University of Technology department of System and Control Theory – faces a special day. At the main entrance of the campus, a Chinese delegation stands unannounced, curious about the development of young universities in the West. Two members of the delegation show an interest in mathematics at the THT (UT's former name, ed.). Actually, Huibert Kwakernaak, professor of the department, is the right man to tell that story, but he is absent. So Olsder, who has just obtained his PhD in Groningen, is asked if he would like to show one of the Chinese scientists the ropes. He receives the rocket scientist Song Jian in his room in the TW/RC building, nowadays known as Cubicus.

Almost fifty years have passed, but Olsder (80) can still remember that day in 1975. He and Jian talk in English about all kinds of things, but after a while they run out of conversation. Olsder decides to end the day with Jian with a beer, at the bar in the Bastille. 'I decided to talk about a study our group conducted on population growth. Suddenly, I saw that this work seemed to interest Jian immediately,' says Olsder.

'In hindsight, I should have noticed it sooner'

In 2015, the mathematician told the Volkskrant more about the research, which was inspired by the Club of Rome, a foundation that was concerned about the future of the world. Olsder in 2015: 'Our idea was an island where a large group of people lived. There would be no immigration and emigration, population growth would be completely natural. But suppose that the population of that island would not have the 'desired' age structure, for example because there are a lot of elderly people living there, how could you correct this? That's what we wondered.'

Chinese Communist Party

Even today, Olsder emphasizes that the research was purely mathematical in nature, not a political experiment. But Song Jian soon saw other possibilities. It only took 33 years for Olsder to figure that out, when the one-child policy had been the norm in China for decades. A country that, ironically, is currently struggling with an unprecedented ageing population. 'In hindsight, I should have noticed it sooner, but I had no idea that Jian had risen to the top of the Chinese Communist Party in the years that followed, that his influence had become so great.'

At conferences of the International Federation of Automatic Control (IFAC), Olsder met the rocket scientist several times. 'In 1978 in Helsinki, but also six years later in Budapest. Then he started talking about my publication. In the meantime he also had a diplomatic passport, he was working the road,' says Olsder, who only really noticed in 2004 that Jian was a man who mattered in China. 'He was passing through and the embassy called me to ask if I wanted to receive him. I thought that would be fun, because I always thought he was a friendly man. A day before his arrival, the embassy asked me if I had already completed the program. I didn't understand it, a program? It was only when he drove up with bodyguards and secretary in two diplomatic cars that I understood. I offered coffee to his entourage.'

'The fact that my work was the first domino depends on coincidences'

In 2008, Olsder – who worked at TU Delft from 1983 until his retirement in 2009 – was approached by a journalist from Trouw. In a book about China's one-child policy, Just One Child by the American anthropologist Susan Greenhalgh, the names of Olsder and Kwakernaak are mentioned a number of times. 'It was only then that I realised that Jian had started working with my model, which I told him about in the Bastille in 1975. Everything fell into place. As a rocket scientist, he had lightning-fast computers at his disposal at the time. This allowed him to make calculations of the model much faster than demographers.'

Beautiful math

When asked whether Olsder feels guilty, he answers in the negative, because his publication was a purely mathematical case. 'I still think it's great mathematics. My opinion on the one-child policy is neutral. On a micro level, it caused distressing cases, but on a macro level, it can be defended if you want to shrink a population.' According to Olsder, it is not only the one-child policy that is to blame for, for example, the imbalance between Chinese boys and girls. 'That also has to do with Chinese culture. Parents also had a preference for a boy before the one-child policy.'

The mathematician is convinced that the policy would have been implemented even if he hadn't told Jian about his publication. 'Perhaps in a slightly different way, or at a different time, but the policy had been introduced. Concerns about China's rapid population growth were not new in 1975. The fact that my work was the first domino depends on coincidences, even though the encounter had far-reaching consequences.' And whether the meeting would have turned out differently if Olsder had known the consequences in advance? 'Then I suspect that I would have changed my mind, perhaps I would not have dared to share my work.'

'I'd love to talk to him again. Not out of sensation, I'm curious to see how he's doing'

Every now and then, Olsder is approached to talk about 'that one meeting' in 1975. In February, an editor of the prominent The Wall Street Journal knocked on his door, even though the emeritus professor does not flaunt his story and certainly does not advertise it. In small circles, people know his story. 'And when I was still working, a Chinese student once asked me about it.'

After his last meeting in 2004, he never spoke to the now 92-year-old Song Jian – mastermind and architect of the one-child policy – again. 'It's a shame, actually. I would like to speak to him again, as I do to all my former colleagues from that time. I don't want to speak to Jian out of sensationalism, or to confront him, but I'm curious to see how he's doing. But I suspect that he lives a bit secluded in the lee. His policies are generally not widely praised politically.'

Song Jian at Geert Jan Olsder's home in 2004.