The Tinbergen brothers


by Auke R. Leen*

In 1969, Jan Tinbergen, aged 66, received the first Bank of Sweden Prize in Economic Sciences in Memory of Alfred Nobel, often mistakenly referred to as the “Nobel prize in economics.” Jan shared the prize with Ragnar Frisch. Four years later, Jan’s younger brother, Nikolaas (Nico), too, was awarded the Nobel Prize in Physiology or Medicine. Nico was 66 years old. He shared the prize with Karl von Frisch and Konrad Lorenz. What lucky coincidence! Or was it? What made it possible for these two siblings to win the prestigious prizes? Was it their genes or their educational and social upbringing? Which brings us to the classic tug-of-war between nature and nurture. Which has the strongest influence on a person’s life, nature or nurture? A look at the brothers’ family background as well as the educational and social environments in which they grew up, might throw light on these questions. We shall also take a look at their work, their groundbreaking ideas and the opposition to these ideas, and the uncanny way in which their lives seemed to duplicate each other.

Jan: Quiet mathematician

Jan was born in April 12, 1903, the eldest of five children: four boys and a girl. Nico, the third child in the family, was born in April 15, 1907. The Tinbergen children grew up in a warm, open and intellectual atmosphere. Before her marriage, their mother, a spontaneous person, worked as a primary teacher. Their father, a real pater familias, always stressing the harmony of family life, studied medieval languages at Leiden University. Next to his occupation as high-school teacher, he also became an expert on medieval Dutch literature. The Tinbergen family lived in a house in The Hague, a town near the Dutch coast, where the parents often organized discussions with the children’s teachers and classmates. The family regularly had outdoor drawing lessons together, went on bike rides or took long walks.

Jan was a quiet child with a strong interest in mathematics and the natural sciences. During high school, he joined a group of students who would meet after school to do experiments in a physics lab. He faithfully attended the weekly lectures, especially those on physics, organized by a learned society. Jan did not only develop in a purely intellectual way. World War I was brought closer to home when his mother gave assistance to war casualties. Children from war-torn Belgium received shelter in the Tinbergen home. The war had a great influence on Jan’s negative attitude towards militarism. He would later refuse to join the compulsory Dutch military service.

In 1921, Jan graduated from high school with the highest honors. Right after graduation, he started his studies in mathematics and the natural sciences at the University of Leiden. To save on boarding expenses, he commuted by train during his first year. To spare his parents even more, he accelerated his studies by attending second year classes in advance. During his spare time, he gave math lessons to high school students. He donated the money he earned to the Dutch Red Cross to help in their relief efforts for the children of Russia, who were suffering from food shortage.

Soon after, Jan became the assistant of Paul Ehrenfest, professor in Theoretical Physics at the university. Later, Jan became a frequent visitor to the Ehrenfest home when he became the private tutor of Ehrenfest’s son. He also took part in the discussions when Ehrenfest was visited by Einstein, Bohr, Heisenberg and Pauli. Notwithstanding what must have been such impressive visits with these famous physicists, Jan shifted his interest to economics on his second year. He explained his move by saying that he realized that self-interest was a major factor that steered his interest towards physics, instead of a genuine concern about his own usefulness in society. At the time, Jan and his future wife whom he met in high school, had decided to dedicate their lives to the goals of the Social Democratic Labor Party. Ehrenfest made a last ditch effort to bring Jan back to the field of physics by advising him to spend the summer of 1923 studying physics at Goettingen in Germany. To no avail. After a fruitless attempt to contact the local Socialist-Communist Student Club, Jan left within a few weeks of staying in Goettingen, overcome by homesickness. Ehrenfest was not totally averse to Jan’s interest in economics. In fact, he was interested in the analogies that could be used in the study of both these fields. Jan’s thesis entitled “Minimum Problems in Physics and Economics” was certainly parallel to this line of thinking. But in the end, Jan’s concern for the causes of poverty made him switch from physics to economics.

physicists at Leiden

Physicists at Leiden, 1924. From left to right: Dieke, Goudsmit, Tinbergen, Ehrenfest, Fermi, Kronig. Jan Tinbergen would later shift his interest to economics.
Copyright © Chicago University Press

Nico: Outgoing adventurer

Nico was the adventurer in the family. He liked sports such as running and playing hockey. Outdoor activities like camping appealed to him. He loved taking pictures of nature. He hated institutionalized activities such as going to school and taking piano lessons. He often missed his classes. Instead, he would wander to the nearby dunes. Except for gymnastics and drawing, in which he excelled, he had poor marks in all other subjects. His parents, however, were not too hard on him. When his report card showed poor marks, his father would eventually ask him if the poor grades were really necessary. And Nico knew what to do. Though it did gnaw on him that he just did what he liked most. In his later studies, he felt compelled to say that he was not merely indulging in his hobbies. With his overriding love for nature (save his youngest brother), Nico was aware that he was an exception to the family nature (norm) of serious study combined with left-liberal thinking. Just for the aesthetic pleasure of it, he could watch the activities of sticklebacks for hours on end. During his high school years, he joined a club that studied wildlife in its natural surroundings. Given his dislike for any formal education, he was still undecided what to do when he finished high school. Only later on in life did he follow his brother Jan’s example by applying his research to social problems.

On the advice of Professor Ehrenfest, Jan’s mentor and family friend of the Tinbergens, Nico went to the German coast of Königsberg in the company of the famous experimental biologist Thienmann, to watch the autumn migration of the wild moose. Back home, he decided to study biology at Leiden University. His studies, however, did not have much influence on his biological fieldwork. Still, he was primarily interested in watching and photographing the behavior of wildlife, for example, herring gulls. He saw all of this, more or less, as a sport. Only gradually did he develop a more scientific attitude towards bird watching. Which meant a painstakingly continuous observation of animals and an ingenious experimentation to check scientific hunches. This would become Nico’s trademark. This was, however, not sufficient. The thesis he wrote, though an uncommon subject at that time, was only accepted after grave doubts. (Maybe because it was less than 30 pages long!) His thesis about the orientation of the digger wasp was more or less the result of a summer family holiday, during which he made the chance discovery of a nearby colony of digger wasps. The day after receiving his doctor’s degree at the age of 25 (the same age that his brother got his doctor’s degree a few years earlier), he married his high-school girl friend and fellow member of the youth nature club. Jan himself, got married years earlier to his high school sweetheart and fellow member of the socialist youth organization.

Introducing econometrics

In the 1930s, Jan devised the first macro-economic model ever. In this model, the focus of economic analysis was no longer on the abstract relation between individual goods and prices. Instead, it was shifted to the concrete relationships between economic aggregates like total income, consumption and investment. His work involved the statistical observation of theoretically founded concepts, namely mathematical economics working with concrete numbers. He was later invited by the League of Nations to analyze the American economy in much the same way that he studied the Dutch economy. This resulted in his time-honored study of 1936, in which he introduced mathematics and statistics to test the different existing trade-cycle theories to the rest of the world. The study, among others, posed the question: is it overinvestment or underconsumption that causes depression? Or is it something else? A confrontation with the facts was necessary to find the answer. This was, however, not a common method in those days – empty theoretical boxes and measurements without theoretical basis characterized economic analysis then. Jan’s model introduced econometrics, a synthesis between mathematics, economic theory and statistics. In this model, it is the task of economic theory to formulate hypotheses, which are in turn formed into mathematical relations that are subsequently tested by the use of statistical data.

For Jan, econometrics is essential in economic research, a vision that was, and still is, being contested. An analogy would best describe the issue. It is an acceptable truth that a city that can be reached by train can also be reached by foot. Applied to the study of economics, one will get the same results, whether using mathematics or plain language, but using the former is more efficient. The argument against Jan’s model runs like this: suppose that using mathematics is the same as taking the night train. The train runs through territory that you cannot see in the dark and thus, you could end up in the wrong station. Translated into economics it means: You may not have looked at the real empirical meaning of each equation and would therefore arrive at the wrong conclusion. But then, counters Jan, suppose there is no day train?

In a Dutch paper in 1950, Jan posed the question: “Can economic theorems be proven without the use of mathematics?” Unlike in physics, economic causes cannot be separated and analyzed in real world experiments. Wages determine prices, prices determine quantities sold, quantities sold determine employment and employment determines wages. It is a shortcoming of our natural languages that these interdependencies cannot be discussed without the use of mathematics. At the end of the same paper he cited an examination in which students were made to solve mathematical problems by verbal logic, something that could have been easily done by using simple mathematics. For Jan a ridiculous situation, indeed, although it can be appreciated as a form of puzzle sport. He compared this situation to that in the world of business and politics and hoped that in the future there would be no need to solve economic problems in the style of the puzzle sport. One day, there would be enough trained econometricians in business and politics who would understand and appreciate its importance in economic analysis.

Jan Tinbergen
Jan Tinbergen
Copyright © Jan Tinbergen Institute, Amsterdam

Criticism from John Maynard Keynes

Jan met the hardest criticism from the man who started the macroeconomic revolution in economics – John Maynard Keynes. Keynes was opposed to the method of multiple correlation which Jan used in trying to quantify the relative importance of the different elements that caused a business cycle. He thought that the method was merely “hocus pocus” since it did not contain all the variables, especially those that cannot be measured, for instance social, psychological, and political factors. And how about expectations and the role they play in making investments? Tinbergen maintained that a residual variable that would touch on the other influences would address this question, and expectations can always be based on the past and thus be extrapolated. Wittily, Keynes asked for an experiment. He remembered that the seventy translators of the Septuagint were shut up in separate rooms with the same Hebrew text and came out with seventy identical translations. What is the chance, he asked, that the same miracle would be vouchsafed when seventy multiple correlators are similarly shut up with the same statistical material? Keynes considered Jan’s method as weak since the materials and relations described in the model were non-quantifiable, variable and non-homogenous. It was a model of thinking that lost is use as soon as one tried to give it an empirical content. A critique echoed in those days by the so-called modern Austrians, of whom Tinbergen’s contemporary Hayek, was an early exponent. Notwithstanding, Tinbergen held Hayek, who was director of the Austrian Business Cycle Institute, in high esteem.

In his Prize Lecture, Jan Tinbergen admitted as much that Keynes may have been right in that he never succeeded in predicting the fluctuations in business investments. After the war, Jan’s interest changed to developmental economics. He became more interested in the structure of the world economy itself and not in its fluctuations.

Keynes’ last comment on Jan’s method, just before World War II, brooked no further discussion. He said that notwithstanding the high opinion he had of Jan as a person, he was still not persuaded that his “statistical alchemy” was ripe enough to become a branch of science. “But,” he continued, “Newton, Boyle and Locke all played with alchemy. So let him continue.”

To get an idea of the awarded work of Jan Tinbergen, the lively correspondence between Keynes and Tinbergen is a stimulating way to start. See Collected Writings of John Maynard Keynes. Volume XIV. Macmillan, Cambridge, 1973. For a recent book of this most important period in economics see Albert Jolink, Jan Tinbergen: The Statistical Turn in Economics: 1903-1955, Chimes, Rotterdam, 2003.

Nikolaas Tinbergen vs colleagues in the medical profession

Criticism to Jan’s work happened at an early stage of his career. The opposite happened to Nico – the work that got him the Nobel Prize went uncontested; the clash with his colleagues came later. By the time Jan held his Prize Lecture, econometrics was firmly accepted in mainstream economics and today, it is still accepted all over the world as a universal benchmark to check the results of different economic policies, debunking Keynes earlier prediction. But the things Nico said in his Nobel Prize Lecture made him almost the laughing-stock of the medical profession. In his lecture, Nico took up the issue of autism, i.e a child’s inability to relate to people and situations in a normal way starting from infancy. He maintained that it was possible to restore an autistic child to normalcy by establishing a secure mother-child bond; thereby suggesting that the cause of early childhood autism is due to the failure of the mother and child to establish or maintain a normal bond.

This, however, was not the kind of research that got him the Nobel Prize. He got it for his work in reviving and developing the biological science of animal behavior: ethology. His first work looked at the landmark orientation of homing wasps. He showed the importance of visual cues that enable the female wasps, despite the many different nests they build, to return to the correct one.


What made Nico really famous is his demonstration of the “hawk/goose effect.” His work explained the behavior of chicks to defend itself from danger: when a goose flies overhead the chick will show no response but if it is a hawk it crouches as if to fend itself from danger. This response was initially thought to be an inborn ability but it is now proven to be learned. The relation between his earlier work and his later theory on autism is obvious. To say that autistic children are “ineducable” and remain dependent all their lives reveals a lack of knowledge about the problem according to Nico, since we still do not have any idea of the causes of autism. What we do have is a mass of disconnected information in search of a theory. All negative predictions about the future are, in reality, no more than statements about the failures of past attempts. According to him, the opinion of experts cannot be trusted since they cannot look into the future. And, he continued, was it not equally the case that until the causes of cholera, smallpox and many other illnesses were discovered, they were considered incurable too?

The strong point in Nico’s ethology-based research on “human animals” echoes his earlier work on ethology: a painstaking and continuous observation of animals and humans in their natural habitat. Zoos and natural history museums had always bored him. Much like parents or persons involved in the day-to-day care and education of autistic children, ethologists have always studied children in their home environment. No wonder it is the first group that supports him most. Nico presented a plausible hypothesis and the design of a promising therapy. To him, adaptedness is fundamental and autism is the result of an emotional imbalance. Contrary to mainstream idea, it is not a result of a disorder in the working of neurotransmitters. Neither is it genetic.

Of the works of Nikolaas Tinbergen, the following books can be recommended: The Study of Instinct, Clarendon Press, Oxford, 1951 and (together with his wife) Autistic Children. New Hope for a Cure, George Allen & Unwin, London, 1983. The first book was a remarkable success. It made continental ethology known all over the world. It is clearly written and is a handbook to do ethological behavior research. The book on autism gives the “animal” ethological base to be used for “human” ethology. For a recent biography of Nico Tinbergen see: Nico’s Nature: The Life of Nico Tinbergen and his Science of Animal Behaviour, Hans Kruuk, Oxford University Press, 2004.


In the introduction we posed the question: nature or nurture? Two brothers with different natures seem to duplicate each other’s fate. The adventurous Nico did not have his brother Jan’s quiet nature and love for study. Still, both were rewarded for their individual efforts, arrived at through different methods. They did share several factors: genes and family upbringing that encouraged intellectual curiosity and independent thinking. And they certainly got the same encouragement from their family to do what they liked best, and to do it well. Well enough to be given the highest accolade one can get for their respective fields. No matter what the critics may say.


* Auke R. Leen was born in 1953 in the Netherlands. At the Erasmus University in Rotterdam he studied economics and philosophy. After working at the Ministry of Economics as the deputy head of the department of financial consumer affairs, he has worked as an assistant professor of economics at Wageningen University and presently is working at Leiden University. He has specialized in the history of economic thought, modern-Austrian economics and the economic analysis of law. His publications include: The Consumer in Austrian Economics and the Austrian Perspective on Consumer Policy (1999) and A Great Revolution in Economics-Vienna 1871 and after (with Lazaros Houmanidis) (2001), as well as numerous articles in different areas of economic theory and policy.

First published 3 March 2004

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