Two economists have come up with a startling and provocative explanation for why countries in colder climates tend to enjoy so much more economic prosperity than countries in tropical areas.
The answer, they say, is Jack Frost.
William Masters of Purdue University and Margaret McMillan of Tufts University used global climate data that has been collected by international organizations since 1960 to conclude that those frosty winter days can do much to determine which countries rise and which fall on the global economic scale.
That answer seems so simple that it almost sounds flippant, but this is serious research, published in the September issue of the Journal of Economic Growth.
"It's very clear in the data," says McMillan. "It's so obvious it just jumps out at you."
Economists have struggled for many years to explain why so much of the world's wealth is concentrated in countries located in temperate rather than tropical regions, and many have suggested that weather must play a part, but this is the first time that economic progress has been linked directly to frost.
"This is the first time that we've had an easy way to compare the climates of different regions in a way that seems to be economically meaningful," Masters says.
Reduced Disease, Better Crops
The economists conclude that frost plays a powerful role in two critical areas. It suppresses diseases such as malaria, and it improves agricultural yields.
The researchers plotted the number of days of frost per month in regions around the entire world. Then they added in the growth in gross domestic product per capita in each region.
"When you do that on a graph, you see there's a positive correlation between the number of frost days and GDP growth," McMillan says.
In other words, if the ground doesn't get cold in the winter, it's going to be a lot tougher to make a living.
"It has been possible for people to become quite civilized and have lots of population growth even in tropical regions," Masters says. "It's just that they've had a hard time getting rich."
All Because of Jack Frost?
Masters says cold weather kills off many disease-carrying germs and insects, thus giving countries in higher latitudes a better chance of keeping deadly killers like yellow fever and malaria under control. That frees up more resources for other purposes, like cultivating crops.
And the crops do better, he adds, because frost enriches the organic material in topsoil.
"In the tropics, that matter is broken down by insects and microbes very quickly, and the nitrogen and carbon in the dead plant material evaporates into the air or is leached into the ground by rainwater," he says. "In a temperate zone, that nitrogen and carbon builds up and remains in the soil in the form of organic matter."
Winter freezing also traps more moisture in the topsoil, preparing the way for spring growth.
The researchers are quick to admit there are exceptions to the frost-produces-riches hypothesis. North Korea and Mongolia are in temperate zones, but both are poor. However, "they have totalitarian governments and exist in isolation," Masters says. Hong Kong and Singapore enjoy great wealth in the tropics, but both are major trading centers.
Notwithstanding those exceptions, "if you look around the world, you can see that most of the poor countries are in the tropics. 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," McMillan adds.
Agriculture Has Always Been Key
If what the economists are saying holds up to further scrutiny, it really means that humans haven't changed much since the beginning of civilization. In his book, Guns, Germs, and Steel, Jared Diamond makes it clear that the road to civilization began when humans first learned that they could grow crops and domesticate animals instead of hunting and gathering.
Agriculture forced humans to settle down in villages, instead of roaming the land in search of food, and it freed up some members of the clan for other pursuits. Some were then able to become kings, bureaucrats, warriors, scientists and artists.
Diamond, professor of physiology at the UCLA School of Medicine, argues that without agriculture, humans would never have had the time to shape the first instruments of war out of metal, nor would they have domesticated horses to carry them off to battle, nor would they have developed the implements of industry that brought us to where we are today.
So during that long journey those who were successful at farming became rich and powerful, conquering much of the world. One might think that disparity between the haves and the have-nots would subside over thousands of years, but it hasn't.
"What we are finding is a 1 or 2 percent per year difference in growth rate," Masters says. "So year by year, a society with frost seems to grow 1 or 2 percent faster."
The research by the two economists is too recent to have provoked much comment from other disciplines, but the reaction so far is mixed.
"There's been a lot of interest," Masters says, "but many people are violently allergic to any explanation that has a whiff of geographic determinism.
"People are very strongly invested in the idea that a country can pull up its socks, as the British say, get its act together, and get the right institutions like the ones that we believe helped make us rich, and that's the road to riches.
"Institutional factors do matter hugely," he adds, but in the end, old Jack Frost is still going to have a say in who gets rich, and who stays poor.