New research by Tufts economics professor Margaret McMillan, who specializes in economic development, suggests that geography and climate may influence wealth levels in certain countries.
Taking a new approach to an old argument, McMillan contents that countries with temperate climates are more prosperous because they have generally have more arable soil, and are also more likely to turn to international trade, since they cannot grow crops year-round.
McMillan's research focuses specifically on ground frost, the frozen layer of moist soil near the Earth's surface. The first frost usually hits Medford in early November, when overnight temperatures begin to dip below the freezing point.
In tropical ecosystems, where the temperature rarely falls below freezing, animal and plant diseases flourish in the warm topsoil. Ground frost also contributes to buildup of organic matter in the soil, which is essential for raising and nourishing crops. The combination of these two factors create infertile land in tropical countries, leading to lower agricultural productivity and lower levels of wealth.
McMillan points out that tropical countries often have very large populations but relatively unproductive work forces. India and Indonesia, two examples of tropical economies, have a combined population exceeding 1.2 billion but an average per capita income of only $2,300, which suggests that economic productivity does not depend on population.
Efficiency, McMillan says, depends on human capital, which is not necessarily related to the number of available workers. Human capital is a measure of the skill and productivity levels of a workforce.
"The idea was that the overall level of human capital is higher in temperate countries," she said. "You can't look at numbers alone."
Ground frost also influences public health by selectively killing organisms that spread human disease. The resulting workforce is generally healthier and more productive.
"People have been talking about the importance of geography in economics," she said. "It's not a continuous variable. There's a certain amount of frost days that are good. If you're below or above that, it's bad for growth."
But the theory is not without counterexample. McMillan said that the few tropical countries that have become extremely prosperous, like Hong Kong and Singapore, have embraced trade, rather than agriculture, as the primary focus of development.
Along with her research partner, William Master from Purdue University, McMillan has found that temperate countries have converged towards high levels of income since the 1960s while tropical nations have diverged to various levels, depending on their economic scale and the extent to which they have embraced trade.
McMillan and Master met in South Africa in the fall of 1998 and began joint research the following fall. They have presented their work on ABC News and in
The Times Higher Education Supplement, a British publication comparable to The Chronicle of Higher Education.
McMillan and Master's initial research leaves more questions to be answered. "We'd like to develop a theoretical model that more explicitly delivers how is it that climate affects productivity and how that productivity translates into surplus that builds up the rest of the economy," she said.
The two also hope to examine how international trade drives growth in tropical economies.
