October 20, 2025
Poor nutrition and illness can limit human growth, so long-term improvements in living conditions are often reflected in increases in average height.
At the individual level, height depends on many other factors, but genetics plays a particularly important role. Not all short people are undernourished or sick, and not all tall people are necessarily healthy. However, when we look at population averages across generations, broad patterns in nutrition and disease burden can play a visible role.
This is why historians often use height as an indirect measure of living conditions. By examining historical changes in height, researchers can gain insights into living standards during periods when little or no other data is available.
This chart presents estimates from Jörg Baten and Matthias Blum, published in the European Review of Economic History (2014). The lines show the average height of men by decade of birth in Denmark, the Netherlands, and Germany, from 1710 to 1980.
For the earlier period, the estimates are based mainly on military conscription records (which measured young men eligible for service), so they are not fully representative of the entire population.
These historical data points are less representative than modern survey data, but the changes are large enough that the overall pattern is meaningful even if exact levels carry some uncertainty.
The chart shows how rapidly average height rose in these countries during the 20th century, a trend consistent with major improvements in health and nutrition.
Yesterday
Most people in the world would think very little before flicking on the lights, charging a mobile phone or turning on a laptop to read this.
But that’s a very different reality from the almost 700 million people in the world who have no access to electricity. While this number is large, it has halved this century, falling from 1.35 billion to 675 million. You can see this in the chart.
However, this progress has been far from even. The number has fallen across all regions except Sub-Saharan Africa, where it has increased.
That doesn’t mean no progress has been made: the share of people in Sub-Saharan Africa with electricity has doubled, rising from 26% to 53%. But population growth has outpaced this expansion, meaning the number of people without electricity has still risen.
April 23
Fertility rates — which measure the average number of children per woman — have been falling worldwide. Since 1950, global fertility rates have halved, from almost 5 children per woman to 2.2.
As a result, global population growth has slowed dramatically, and many countries' populations are expected to decline by the end of the century.
This is because fertility rates in many countries have fallen below the “replacement level”. This is the level at which a population replaces itself from one generation to the next. It’s generally defined as a rate of 2.1 children per woman.
The map shows which countries had fertility rates above and below this level in 2025. This is based on projections from the UN World Population Prospects.
April 21
Most of the world's poorest people still rely on solid fuels — such as crop waste, dung, wood, and charcoal — for cooking and heating.
These fuels generate household air pollution when they’re burned. This has health impacts for those who breathe them in, and can increase the risk of a range of illnesses, including cardiovascular disease, stroke and some cancers.
Estimates from the Institute for Health Metrics and Evaluation suggest that indoor air pollution causes almost three million premature deaths each year. That’s three million people dying earlier than they otherwise would without this pollution.
As shown on the chart, deaths from indoor pollution have fallen as more people get access to cleaner cooking fuels. Improving access to clean energy could prevent many more early deaths.
April 18
Cervical cancer death rates among women in the United Kingdom have fallen by around 80% since 1950. You can see this reduction in the chart.
This progress happened for a couple of key reasons.
The first was the introduction of population-level screening programs in 1988. Across the UK, women are invited to get a regular smear test to detect precancerous changes or cervical cancer cases early, when treatment has much better odds of success.
Another, and more recent innovation, which could put the UK on the path to eradicating cervical cancer completely, is the rollout of the human papillomavirus (HPV) vaccine. This protects someone from the HPV infection, which can later develop into cervical cancer.
In schools across the country, girls in their early teens are offered the HPV vaccine, effectively offering them long-lasting protection. I was one of the first cohorts of girls in the UK to receive this, and it’s something I’m incredibly grateful for.
The UK is not alone in its progress: a number of countries have managed to reduce cervical cancer death rates in recent decades.
April 16
France generates two-thirds of its electricity from nuclear power, making it the country’s dominant power source.
As the chart shows, that’s far more than the average across Europe, which is 20%, and the world as a whole, at 9%.
Nuclear power is a low-carbon electricity source, giving France a very clean electricity mix for decades.
Per unit of electricity, France emits far less greenhouse gas than its neighbors and has some of the lowest-carbon power in the world. The global average, based on lifecycle emissions, is 472 grams of carbon dioxide equivalents (CO2e) per kilowatt-hour of electricity generated. In France, this figure is 42 grams.
April 14
In every region of Africa, hunger is more prevalent than a decade ago.
The chart shows the increase in the share of the population that is undernourished, comparing 2014 and 2024 (the most recent year available). These estimates come from the Food and Agriculture Organization of the United Nations.
The situation across Africa is dire. In Middle Africa, where hunger is most acute, almost 1 in 3 people are undernourished. In Eastern Africa, the figure is roughly 1 in 4. Across Africa as a whole, it's 1 in 5.
This marks a reversal of a longer positive trend: over the preceding decades, hunger had been falling across much of the world, including parts of Africa. That progress has now stalled or gone into reverse. Conflict, extreme weather, and the economic disruption of the COVID-19 pandemic have all contributed.
April 11
The concept of “leapfrogging” is popular in development. It suggests that, as they develop, lower-income countries can skip intermediate technologies or systems and go straight to the modern equivalent.
One example of this is the use of landlines and mobile phones.
The landline telephone was invented in 1876 and became a dominant form of communication across Europe and North America. As you can see in the chart, it was increasingly adopted in the United States and the United Kingdom throughout the 20th century.
However, mobile phone adoption increased rapidly in the 1990s, and landlines have declined since the millennium. Mobile phones have become a substitute.
But many countries have almost skipped landline adoption entirely. Ghana and Nigeria are good examples: landline subscriptions have remained extremely low, and instead, mobile phone adoption has exploded.
