Free Factfulness: Ten Reasons We're Wrong About the World – and Why Things Are Better Than You Think by Hans Rosling Page A

at a teachers’ conference in Norway (but I don’t mean to be too hard on the Norwegians: it might just as well have been in Finland too). Many of these teachers were teaching global population trends as part of their social science classes. When I turned my head around and saw the results from the live poll on the screen behind me, I couldn’t find words. I remember thinking that there must be something wrong with the polling devices.
    FACT QUESTION 5
    There are 2 billion children in the world today, aged 0 to 15 years old. How many children will there be in the year 2100, according to the UN?

    Before asking the question, I had told the teachers, “One of these three lines shows the official UN forecast. The other two lines, I just made up.”
    Again, chimpanzees pick the correct line 33 percent of the time. The teachers in Norway? Only 9 percent. I was shocked. How could such an important group of people score worse than random? What were they teaching the children?
    I kind of hoped the polling devices were broken. But they were not. We got the same terrible results in our public polls. In the United States, the United Kingdom, Sweden, Germany, France, and Australia, 85 percent of people picked the fake lines. (The full country breakdown is in the appendix.)
    The experts at the World Economic Forum? They answered much better than the public. Almost as well as chimpanzees. Twenty-six percent got it right.
    Thinking it over more calmly after the teachers’ conference was over, I started to see the size of the knowledge problem. The number of future children is the most essential number for making global population forecasts. So it is central to the whole sustainability debate. If we get this number wrong, we are going to get a lot else wrong. Yet almost none of the highly educated and influential people we have measured have the slightest knowledge of what the population experts are all agreeing about. The numbers are freely available online, from the UN website, but free access to data doesn’t turn into knowledge without effort. The UN line is alternative C: the flat line at the bottom. UN experts expect that in the year 2100 there will be 2 billion children, the same number as today. They don’t expect the line to continue straight. They expect no further increase. I’ll soon get back to this.
The Straight Line Instinct
    This graph shows the world population since the year 8000 BC . That’s when agriculture was invented.

    Back then, the total human population was roughly 5 million people, spread along coastlines and rivers all over the world. The total of humanity was smaller than the population of one of our big cities today: London, Bangkok, or Rio de Janeiro.
    This number increased only slowly for almost 10,000 years, eventually reaching 1 billion in the year 1800. Then something happened. The next billion were added in only 130 years. And another 5 billion were added in under 100 years. Of course people get worried when they see such a steep increase, and they know the planet has limited resources. It sure looks like it’s
just
increasing, and at a very high speed.
    When looking at a stone flying toward you, you can often predict whether it is going to hit you. You need no numbers, no graphs, no spreadsheets. Your eyes and brain extend the trajectory and you move out of the stone’s way. It’s easy to imagine how this automatic visual forecasting skill helped our ancestors survive. And it still helps us survive: when driving a car, we constantly predict where other cars will be within the next few seconds.
    But our straight line intuition is not always a reliable guide in modern life.
    When looking at a line graph, for example, it’s nearly impossible not to imagine a straight line that stretches beyond the end of the trend, into the future. On the population graph on the next page, I added the dashed line to clarify what I think people are instinctively imagining. Of course they get worried.

    Let