Two-hundred years ago, there was nowhere an average citizen could expect to live beyond 40. Now, the average person can expect almost double that.
The simple thing to do is thank better hygiene, improved diets and the scientists that made the big advances. But there's a more complicated, more interesting story here - one involving economics.
Strong economic growth explains strong improvement in the chart (eg South Korea), while weak economic growth is associated with more meagre improvements (eg USSR/Russia).
There is no shortage of people decrying economic growth. Economic growth brings costs and downsides and there's no point ignoring them. But economists should push back against those criticising growth in general - we are not always effusive enough about the long-run upside of growth.
Economic growth is poorly understood. I've seen people trying to do analysis of why some countries are rich and others poor at a single point in time (eg America is rich because Africa is poor).
In fact the only way to explain why some countries are rich and others poor is to look at economic growth across a long period. Those with three per cent economic growth over the last 100 years (or 10 per cent for 30 years) are rich countries. Those without such a history are poor.
Living standards depend on growth. If economists seem obsessed with it, this is why.
The important corollary to the growth story is that economics depends on science.
One of the best models of long-run growth assumes economic output depends on only three things: capital, labour and technology. Technology is the most important of these in the long run.
Health sciences make for more productive people that live longer. Engineering has given us productivity multiplying devices from the plow to the spreadsheet. Chemistry and agricultural science have multiplied exponentially the bounty of our farmlands.
History doesn't guarantee our progress. Progress requires brilliant minds pushing forward into the darkness, with no guarantee of reward. We owe our scientists an enormous amount and still pay most of them comparatively little.
Science depends on economics. It rarely funds itself. It may pay itself off later, but at the time, not so much. Science typically requires a rich country in order to proceed.
The enlightenment and the origins of formal science were principally in Europe, when it was the richest part of the globe. Now America is at the forefront of discovery.
Wealth begets discovery. The number of scientists in the world keeps increasing as we grow richer.