The Best News of Your Lifetime

I mentioned this in class about 10 days ago, but here’s a chart from the World Bank (an anti-poverty NGO):

It is reasonable to point out that this only goes back to 1980, and that there had to be improvements before then.The $1.90/day value is the World Bank’s estimate of subsistence level consumption. This was essentially 100% in 1680. So, the improvement from 100% to 42.2% took 300 years.

It is also worthwhile to think in terms of absolute numbers (populations are in millions):

Year	Population at Subsistence	Population Above Subsistence
1680	590	10
1980	1,850	2,590
2015	736	6,622

Do note that I made up the number in the cell at the top right. The truth is the data doesn’t go back that far. But our best estimate for 1820 is 6% of the world’s population living above subsistence level, so the choice of 10 out of 600 in 1680 seems plausible.

These numbers demonstrate a phenomenon that economists understand well, but that the general public experiences as something they feel is wrong. It’s called a Kuznets Curve, and it shows up in a number of areas where environmental issues are a concern. Theoretically, it’s a very basic result that emerges in theoretical models without making unusual assumptions.

Roughly, it’s an explanation of why things sometimes get worse before they get better. In this case, it didn’t take much of an improvement in well-being for population to start rising: people lived longer, children became more likely to survive until adulthood, and so on. What doesn’t immediately change is the desire of adults to have children (who grow up to care for the adults in their senior years — that’s how human societies “did social security” on their own for millennia). Anyway, it takes a couple of generations for people to realize that isn’t necessary and to reduce the number of children they have, and invest more in each one (do note that while this is happening in many places after the advent of widely available birth control, it was observed in most of the now developed world for decades before “the pill” became available or surgical abortion was common).

In other cases, it explains why developed countries tend to be cleaner and less polluted than developing ones. The first thing people do is pollute and make money. Later on, that money is used to reduce pollution.

N.B. With science, there’s always a conflict between data and anecdotes. Scientists are able to say serious things because of their focus on data. But humans evolved in a world of anecdotes, and we still tend to prefer them. Journalists love anecdotes: they’re the basis of their stories. A problem then arises with Kuznets Curve behavior: for a while at least, the number of anecdotes increases for a while even though the overall situation is changing. So, the table above suggests that the maximum number of anecdotes about subsistence living occurs fairly recently (and actually peaked somewhere around 1970), even though the proportion of people whose lives are advancing out of subsistence has been increasing for centuries. In fact, while the number living at a subsistence level is dropping for the world as a whole, it’s still increasing in sub-Saharan Africa (even though the rate is improving there too).