HUMANS are a gloomy species. Some 71% of Britons think the world is getting worse; only 5% think it is improving. Asked whether global poverty had fallen by half, doubled or remained the same in the past 20 years, only 5% of Americans answered correctly that it had fallen by half. This is not simple ignorance, observes Johan Norberg, a Swedish economic historian and the author of a new book called “Progress”. By guessing randomly, a chimpanzee would pick the right answer (out of three choices) far more often.

People are predisposed to think that things are worse than they are, and they overestimate the likelihood of calamity. This is because they rely not on data, but on how easy it is to recall an example. And bad things are more memorable. The media amplify this distortion. Famines, earthquakes and beheadings all make gripping headlines; “40m Planes Landed Safely Last Year” does not.

Pessimism has political consequences. Voters who think things were better in the past are more likely to demand that governments turn back the clock. A whopping 81% of Donald Trump’s supporters think life has grown worse in the past 50 years. Among Britons who voted to leave the European Union, 61% believe that most children will be worse off than their parents. Those who voted against Brexit tend to believe the opposite.

Mr Norberg unleashes a tornado of evidence that life is, in fact, getting better. He describes how his great-great-great-great grandfather survived the Swedish famines of 150 years ago. Sweden in those days was poorer than Sub-Saharan Africa is today. “Why are some people poor?” is the wrong question, argues Mr Norberg. Poverty is the starting point for all societies. What is astonishing is how fast it has receded. In 1820, 94% of humanity subsisted on less than $2 a day in modern money. That fell to 37% in 1990 and less than 10% in 2015.

Not only have people grown much more prosperous; they also enjoy better health than even rich folk did in the past. This is due partly to galloping progress in medical science. When the swine flu pandemic threatened to become catastrophic in 2009, scientists sequenced the genome of the virus within a day and were producing a vaccine in less than six months.

The spread of basic technology, allowing for clean water and indoor plumbing, may have helped even more. Louis XIV’s palace was the pinnacle of 18th-century grandeur. Nonetheless, without flush toilets, it stank. “The passageways, corridors and courtyards are filled with urine and faecal matter,” wrote a contemporary observer. Now 68% of the world’s population have modern sanitation—a luxury denied to the Sun King—up from 24% in 1980.

People are growing smarter too. Americans scored, on average, 100 points on IQ tests just after the second world war. By 2002, using the same test, this had risen to 118, with the biggest improvements in answers to the most abstract problems. This “Flynn Effect”, as it is known, is observed in all countries that have modernised. The most likely reasons are better nutrition and the spread of education—brains that are well-fed and well-stimulated tend to work better—and environmental improvements such as the removal of lead from petrol.

Mr Norberg agrees with Steven Pinker, a psychologist, that humankind is also experiencing a “moral Flynn Effect”. As people grow more adept at abstract thought, they find it easier to imagine themselves in other people’s shoes. And there is plenty of evidence that society has grown more tolerant. As recently as 1964, even the American Civil Liberties Union agreed that homosexuals should be barred from government jobs. In 1987 only 48% of Americans approved of interracial dating; in 2012 that figure was 86% (and 95% of 18- to 29-year-olds). The caste system in India has eroded as individualistic values have spread: the proportion of upper-caste weddings with segregated seating fell from 75% to 13% between 1990 and 2008.

Despite the bloody headlines, the world is far safer than it used to be. The homicide rate in hunter-gatherer societies was about 500 times what it is in Europe today. Globally, wars are smaller and less frequent than they were a generation ago. The only type of violence that is growing more common is terrorism, and people wildly overestimate how much of it there is. The average European is ten times more likely to die by falling down stairs than to be killed by a terrorist. Evidence that the past was more brutal than the present can be gleaned not only from data but also from cultural clues. For example, children’s nursery rhymes are 11 times more violent than television programmes aired before 9pm in Britain, one study found.

That life is improving for most people does not mean it is improving for everyone. Male blue-collar workers in rich countries have seen their earnings stagnate. Even if the statistics fail properly to capture the benefits they enjoy as consumers of new technology, the slippage in their status is real and painfully felt.

Global warming is a worry, too, but Mr Norberg hopes that human ingenuity will tame it. He writes with enthusiasm about all kinds of green innovation. For example, thanks to more efficient farming technology, the world may have reached “peak farmland”. By the end of the century, an area twice the size of France will have been returned to nature, by one estimate.

This book is a blast of good sense. The main reason why things tend to get better is that knowledge is cumulative and easily shared. As Mr Norberg puts it, “The most important resource is the human brain...which is pleasantly reproducible.”