Numbers don’t lie succinctly explains 71 things we need to learn about the world. By focusing on key themes such as the environment, technology, people and transportation, Vaclav Smil helps us see that whilst numbers may not lie, the truth they convey can be misunderstood.

Get the book here: Numbers don’t lie by Vaclav Smil

Key idea #1 – The best return on investment for reducing the mortality rate is vaccinations

Death due to infectious diseases in infancy and childhood remains the cruellest fate in the modern world and one of the most preventable. When it comes to helping nations pull themselves out of poverty and improve their quality of life, there is one clear winner which will do that: vaccinations.

Today the standard practice is to innoculate children with a pentavalent vaccine that prevents diseases such as diphtheria, tetanus, pertussis and polio as well as meningitis, otitis and pneumonia. Whilst in many developed nations this is common practice, there are still various places in the world – especially areas impacted by conflict – which do not do this.

A 2016 study supported by the Bill and Melinda Gates Foundation found that for every dollar invested in vaccination, $16 is expected to be saved in healthcare costs and lost wages and productivity caused by illness and death due to these preventable illnesses.

Whilst eliminating infectious diseases completely appears to still be unlikely – the worldwide infection rate for Polio dropped from 400,000 in 1985 to fewer than 37 in 2016 – new threats which have appeared over the years such as Ebola, Zika virus and Covid-19 are most likely best fought through vaccinations.

Key idea #2 – Life expectancy may be topping out

Ray Kurzweil, Google’s chief futurist says that if you can hang on until 2029, medical advances will start to add one additional year, every year to your life expectancy.

However, Smil with the use of data from various countries has an alternative suggestion. In 1850, the combined life expectancies of men and women stood at 40 years in the United States, Canada, Japan and much of Europe. Since then, the life expectancies of individuals has increased dramatically with the maximum topping out at 87 years in Japan.

However, without fundamental discoveries which influence the way we age, this trend may weaken and finally end. The long-term trajectory of Japanese female life expectancy fits a symmetrical logistic curve that is already close to its asymptote of about 90 years. This is happening for other affluent countries too.

Key idea #3 – Money may not always buy happiness

In 2019, Finland was considered to be the worlds happiest country for a second time in a row, followed by Denmark, Norway and Iceland. The UK and US finished 15th and 19th respectively.

What rarely gets reported on is what makes up these national scores. On top of GDP per capita, other factors such as social support (if people have others to count on when in need), healthy life expectancy, freedom to make life choices, generosity and perceptions of corruption.

Whilst the top-ranking countries appear to follow a pattern (they’re all in the northern hemisphere and two of them are Scandinavian) more interesting clues are provided by countries that would appear out of place. Mexico is ahead of France, Panama is ahead of Italy, Guatemala is ahead of Saudi Arabia and Argentina is ahead of Japan. Whilst the latter members are richer, more stable, less violent and offer an easier life than the first countries, Smil makes the observation that the happier ones are all former Spanish colonies, hence overwhelmingly Catholic. Maybe money may not buy happiness after all.

Key idea #4 – American exceptionalism isn’t backed by evidence

Belief in “American exceptionalism” – that unique blend of ideas and love of liberty made so powerful by great technical and economic accomplishments is alive and well. However, such proclamations cannot mean anything if they cannot stand up to the facts. A countries GDP or the number of warheads they have shouldn’t be used as a measure of exceptionalism – life, death and knowledge should.

Infant mortality is an excellent proxy for a wide range of conditions including income, quality of housing, nutrition, education and investment in healthcare. It is very rare for infants to die in affluent countries due to good housing, well-educated parents and easy access to medical care. However, the US does not figure among the top 25 nations. Its mortality is higher than France, Germany Japan and Greece (a country portrayed as a basket-case after the financial crisis). Some may excuse the poor rating by saying European countries with homogenous populations, however, Europan countries such as France and Germany have a mix of immigrants. What really determines infant mortality is parental knowledge, good nutrition, the extent of economic inequality and access to universal healthcare (with the US being the only affluent country without access to universal healthcare).

Looking at the other end of the spectrum, the US life expectancy is nearly 79 years for both sexes. This means it doesn’t rank among the top two dozen countries worldwide and again is behind Greece as well as South Korea.

Education or lack of is another theme. In the Organisation for Economic Co-operation and Development Programme for International Student Assessment. The US in Math ranks below Russia, Slovakia and Spain and far lower than Canada, Germany and Japan. Similar trends are found in Science and English.

The author states that these facts may be discomforting, but there is nothing arguable about them. Politicians may look far and wide for American exceptionalism, however, when it comes to the things that matter, there’s a lot of progress to be made.

Key idea #5 – Don’t write off diesel engines just yet

Today Diesel engines remain at least 15 to 20 percent more efficient than their gasoline-fueled rivals. They also have several advantages: they use fuel of a higher energy density (diesel contains 12 percent more energy than the same volume of gasoline meaning they can go further on the same tank volume); their self-ignition compression ratios are twice as high as gasoline meaning more complete combustion and in the cooler exhaust gas and they can also burn lower quality and cheaper fuel.

Because of this, Diesel is the uncontested enabler of massively centralised industrial production and the irreplaceable prime movers of globalisation. Diesel powers virtually all container ships and all car carriers of vehicles, bulk commodities and everything else important for development. Without diesel, the speed and extent of globalisation would not have been possible.

Over the past century, these engines have increased in both capacity and efficiency and because of this diesel is here to stay. There are no readily available mass-mover alternatives that could keep the economy moving as affordably and efficiently as these engines.

Key idea #6 – Modern cars have terrible weight to payload ratios

The best selling car a century ago in the United States, the Ford Model T, managed to get a watt from every 12 grams of its internal combustion engine. Now engines in the best selling American cars are getting a watt per gram resulting in a 92 percent improvement. However, during the past century, engine power has increased more than 11 fold to 170 kilowatts meaning that despite a huge drop of mass/power density, today’s typical car engine is hardly lighter than it was a century ago. Its mass has roughly tripled and because most commuters drive alone, you have the worst possible ratio of weight to payload.

Assuming a 70kg adult, the below table suggests:

Method of transport	Weight to payload ratio
Bicycle	0.1
Scooter	0.16
Small cars	7.3 – 16
Medium cars	28
Large cars	32

To put this into perspective, a fully packed Boeing 787-10 has a better weight to payload ratio than a solo occupied small car such as a Citroen 2-CV. Its maximum takeoff weight is 254 tonnes; with 330 passengers this comes to a rate of around 5.3.

Whilst new technologies are improving and this ratio is improving in some vehicles, nothing would slash this ratio down as much as two or even four people in one vehicle.

Key idea #7 – Eating less red meat is better for the enviroment

Eating meat (and beef in particular) has joined a list of undesirable habits as the concerns about meat’s drawbacks – ranging from the health effects to environmental damage – have been discussed in recent years.

Whilst meat is an excellent source of protein, cattle are inefficient converters of food into meat and affluent countries have expanded their meat production to such an extent that the principal task of agriculture has not been to grow crops for people but for animals – in North America and Europe about 60 percent of the total crop harvest is now destined for feeding. This has major environmental consequences, particularly due to the need for fertiliser and water.

Whilst research cited in the book suggests that eating meat in moderation is not associated with any adverse outcomes, studies into alternative diets such as the Japanese diet which has a more restricted meat consumption found that there is no additional health or longevity benefits from the high consumption of meat. Due to this the author suggests moderating your meat intake to help reduce the environmental impact more than to curb any negative health outcomes.