Distributed December 2, 2002
For Immediate Release
News Service Contact: Scott Turner
New theory explains economic growth in terms of evolutionary biology
The struggle for survival that characterized most of human existence stimulated a process of natural selection that
conferred an evolutionary advantage on humans who had a higher genetic predisposition for a careful rearing of the next
generation. This evolutionary change permitted the Industrial Revolution to trigger a change from an epoch of stagnation
to an age of sustained economic growth, according to the first theory that integrates the fields of evolutionary biology
and economic growth. This research by Brown University economist Oded Galor and Omer Moav from the Hebrew University is
the lead article in the current Quarterly Journal of Economics.
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PROVIDENCE, R.I. — It took an evolutionary leap in the human species to help trigger the change from centuries of
economic stagnation to a state of sustained economic growth, according to the first theory that integrates evolutionary
biology and economics.
“Until now, economic growth theory did not have implications for evolutionary biology, and evolutionary biology did not
have implications for economic growth,” said lead theorist Oded Galor, professor of economics at Brown University.
This new theory, the first of its kind ever proposed in the economics literature, appears as the lead article in the
current Quarterly Journal of Economics. It is co-authored by Omer Moav of the Hebrew University of Jerusalem.
“The struggle for survival that had characterized most of human existence stimulated a process of natural selection and
generated an evolutionary advantage to human traits that were complementary to the growth process, triggering the
takeoff from an epoch of stagnation to sustained economic growth,” the authors wrote in their study.
The evolution of the human brain in the transition to Homo sapiens “increased the evolutionarily optimal investment in
offspring's quality,” said Galor. “This was due to the complementary relationship between brain capacity and the return
to investment in human capital.”
The process gave an evolutionary advantage to people who had higher valuation toward offspring’s quality, Galor said.
“The subsequently increased prevalence of this genetic trait in the population ultimately permitted the Industrial
Revolution to trigger a transition to a state of sustained economic growth.”
The critical natural selection that occurred prior to the Industrial Revolution involved the fundamental tradeoff
between child-caring and child-rearing. The “epoch of stagnation” gave an evolutionary advantage to a higher-quality
smaller family rather than to lower-quality larger families, Galor said.
“Valuation of quality, through better nourishment and education for children, fed back into technological progress. And
as technology advanced, it fed back into more education. Human capital took off. This leap in evolution came to dominate
the population as a whole, and centuries of economic stagnation ended.”
The authors attribute acceleration in this evolutionary process to the emergence of the nuclear family that fostered
intergenerational links. Prior to the agricultural revolution, 10,000 years ago, people lived among hunter-gatherer
tribes that tended to share resources more equally.
“During this hunter-gatherer period, the absence of direct intergenerational links between parental resources and
investment in their offspring delayed the evolutionary advantage of a preference for high-quality children,” said the
authors.
In fact, according to the theory, a switch back to a quantity emphasis began to take place in the 20th century.
“During the transition from stagnation to growth, once the economic environment improved sufficiently, the evolutionary
pressure weakened and the significance of quality for survival declined,” said Galor. The inherent advantage in
reproduction of people who highly value a large number of children gradually dominated and their fertility rates
ultimately overtook the fertility rates of people who value high-quality children, he said.
“Oded Galor’s tendency to ask big, important questions, to be tackled in ambitious and technically sophisticated models
have earned him a well-deserved reputation as one of the most ingenious and interesting growth-theorists of our age,”
said Joel Mokyr, professor of economics and history, Northwestern University. Mokyr is a leading expert on the history
of technological progress and the Industrial Revolution.
“Galor and Moav have opened a new and potentially very fruitful vein of thinking about the history of economies in the
very long run,” said Mokyr. “This pioneering paper is a breakthrough in its use of population dynamics in long-term
historical change and in applying Darwinian logic to the history of mankind.”
The predictions of the proposed theory are consistent with the time path of population, technology and income since the
emergence of Homo sapiens, said Galor.
“Once biologists identify the genes that control fertility behavior, the predictions of the theory in the context of the
evolution of the human species could be tested as well, comparing genetic valuation for quality in hunter-gatherer
tribes to those in societies that have experienced the Neolithic revolution,” Galor said.
According to the authors, earlier episodes of technological progress did not generate a “takeoff” because the necessary
human evolutionary change had not yet completed its course.
“The population did respond to higher return to education and investment in human capital, but not aggressively enough
to generate an acceleration in the rate of technological progress and sustained economic growth,” said Galor.
The theory generates an alternative intriguing prediction, he said.
“It suggests that during the epoch of stagnation, men who were from a physiological viewpoint moderately fertile (men
with a moderate sperm count), and who were therefore induced by nature to invest more in the quality of their offspring
had an evolutionary advantage over highly fertile individuals,” Galor said. This would suggest that sperm count has
declined in the last thousands of years, he said.
The National Science Foundation supported Galor's research.
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