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Opinion: What the numbers show

Vaclav Smil is a numbers freak. Dr. Smil is Distinguished Professor Emeritus at the University of Manitoba and a Fellow of the Royal Society of Canada. He has published a variety of books on such diverse topics as technological innovation, risk assessment, environmental and population change, and public policy concerning energy. A couple of years ago, he pulled many of his research findings together in a book, “Numbers Don’t Lie: 71 Things You Need to Know about the World.”

I obtained a copy of the book quite by accident. I had ordered a murder mystery from When it arrived on my doorstep, it did indeed have the cover that I’d expected. But, inside the cover was Smil’s book. My initial thought was to return it as a defective item, but I started to read a few chapters and became hooked. The work is entertaining and filled with “statistical truths” that I’d like to share. So, here are a few of the 71 things that we “need to know” about the world.

Tall kids

Being tall in a society has many attendant positive attributes. Tall people are often seen as having higher cognitive ability, higher lifetime earnings, and higher social status. In the last century, the average height of a European male was nearly 5’7” (170 centimeters). It was less than that elsewhere in the world. Unfortunately, historical record-keeping for girls and women was not reported.

Within Europe, the “dairy” countries, particularly Holland, produced much taller boys and men, while countries with which wine is more closely associated tended to have shorter males. But, during the 20th century, as milk consumption among children spread throughout the world, male children grew to be 3 inches taller than their predecessors.

Smil shows the progression in Japan where milk became a staple of children’s diets. In 1900, the height of Japanese males at 18 years of age was 160 centimeters, and it increased every decade. By 1960, it was 166 centimeters; in 1980, 170 centimeters; and in 2020, 172.6 centimeters. The message, Smil says, is clear: “The easiest way to improve a child’s chances of growing taller is for them to drink more milk.”

Best investment: Vaccination

In the modern world, death from preventable disease is, according to Smil, the unkindest cut of all. Our health is dependent on having clean water, adequate nutrition, and proper sanitation. But if you take all of the factors that come into play and then judge their benefits according to their cost-benefit ratios, “vaccination is the clear winner.”

Smil cites a study, sponsored by the Bill and Melinda Gates Foundation, of nearly 100 low- and middle-income countries, between 2011 and 2020. He states, “For every dollar invested in vaccination, $16 is expected to be saved in healthcare costs and the lost wages and lost productivity caused by illness and death.” The highest benefit came from averting measles, and that was 18 times the average.

The value of sweat

During the early years of human evolution, we had to hunt for animal protein by foot, the same as cats and other carnivores. This meant that we had to chase our dinner and catch it. In order to run fast and far, bodies — whether human or some other species — have to regulate two critical factors: temperature and hydration.

Our advantage over the lion, which is bigger, faster, stronger, and more deadly than a human being, is our extraordinary ability to regulate our body temperature. We have this edge because, as Smil says, “we are superstars of sweating.” We know that when horses run, they sweat profusely, losing about 100 grams of water per hour per square meter of skin.

Camels, which have been used as transport like horses, can lose up to 250 grams of water per hour per square meter of skin. Smil states, “However, a human being can easily shed 500 (grams of water per hour per square meter of skin), enough to remove between 550 and 600 watts’ worth of heat.”

Naturally, when we lose that much water, it must be replaced through rehydration. And this is our second advantage. Smil points out that when we lose water, we don’t have to make up the deficit immediately. We can tolerate considerable temporary dehydration, so long as we rehydrate in a day or so.

In summary, Smil postulates: “In the race of life, we humans are neither the fastest nor the most efficient. But thanks to our sweating capability, we are certainly the most persistent.” (Author’s comment: Only men sweat; women glisten.)

Quality of life

This one is tricky. Various international organizations attempt to rank countries according to a wide range of variables. Some rely heavily on economic factors, like GDP (the total economic output within a society) per person. Others utilize scores on subjective perceptions, like happiness. Still others may develop a descriptive score based on protein consumption or the availability of health-care services.

Smil, who has analyzed all the numbers generated by such organizations, concludes: “My own choice of a single-variable measure for rapid and revealing comparisons of quality of life is infant mortality.” He chooses this one bit of datum, with lots of caveats, because it is impossible to achieve a low infant mortality rate (the number of babies that fail to survive for one year per 1,000 live births) unless all of the other variables for a pleasant, long, and rewarding life are present.

As late as 1850, infant mortality in Western Europe and the United States was in a range between 200 and 300. That means that every fifth to approximately every third child did not survive for 365 days. As the benefits of the Industrial Revolution kicked in, those rates began to decline. By 1950, the infant mortality rates (IMR) in those same countries were in a range from 35 to 65, meaning that (give or take) one out of every 20 newborns did not survive its first year.

Now, wealthy countries have an infant mortality rate of about 5, meaning that only one of every 200 live births will not see its first birthday. This number is slightly higher for countries with large populations and high immigration (like the U.S, which has an IMR of 6) and lower for countries that have small, homogenous populations with little immigration (like Iceland with an IMR of 3 or Japan with an IMR of 2).

I’m not exactly sure why we really “need to know” these things about the world, but I do believe that knowledge is useful, and I’m impressed that Smil relies on fact-based information.

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Jim Glynn is Professor Emeritus of Sociology. He may be contacted at


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