Why are some nations wealthy and others poor? The key to national prosperity may be cold weather, according to research by a Tufts economist.

Medford/Somerville, Mass. [10.17.01] -- Researchers have wondered for years why countries in cold climates tend to benefit from greater economic prosperity than those with warmer weather. The explanation, according to research published by a Tufts economist, may be extraordinarily simple: "It's the weather, stupid!"

   Tufts' Margaret McMillan, an assistant professor in Tufts' Economics Department, and a colleague at Purdue University spent the last two years comparing climate data and the average income of countries from around the world.

   According to ABC News, the pair concluded that "Those frosty winter days can do much to determine which countries rise and which fall on the global economic scale."

   Frost, concluded McMillan and her colleague, plays two important roles.

    "First, frost helps farmers increase agricultural productivity. It allows a build-up of organic matter that leads to fertile topsoil," reports The Times Higher Education Supplement -- a leading higher education news source in London. "Second, frost helps people control disease, particularly malaria, by making insects dormant."

   The result: countries with colder climates have a bigger workforce and larger agricultural yields.

   "There's a positive correlation between the number of frost days and gross domestic product growth," McMillan said in an ABC News report.

   The findings, reports the national news network, are the first to directly link frost with economic growth.

   "A generation of economists have focused on institutions as the key difference between societies," McMillan said in a report by United Press International. "Many of them -- including me -- are now quite surprised to find that biophysical factors like climate matter too."

   Of course, there are exceptions to the rule, including countries like Singapore, which is a wealthy nation located in a tropical climate.

   But McMillan has a theory to explain that as well.

   "If you look around the world, you can see that most of the poor countries are in the tropics," she said in an ABC News report. "The exceptions have been able to get out of this low-level productivity trap by opening up to trade and not relying heavily on agriculture."