Archaeological studies show that societies in the past were very violent. Often more than 10% of deaths were the result of one person killing another.
In this chart I have included all the available archaeological evidence that I could find. You can find the (long) list of data sources by clicking on the chart.
Ethnographic evidence confirms that violence is very common in nonstate societies and drastically higher than in modern state societies.
This chart shows the ethnographic evidence. You can find the (long) list of data sources by clicking on the chart.
The historical record of homicide rates in Europe shows that modern levels of violence were only arrived at after a long decline.
Here we compare rates of violence - number of people killed per year, rather than share of deaths that were violent.
Once again, ethnographic studies show that violence in nonstate societies was much higher than in modern state societies.
This is a long-term view of wars and genocides.
The past was not peaceful.
But why is violence declining?
One important change is the improving literacy and education...
...as education goes together with increasing political freedom.
Countries with higher educational attainment in the past are more likely to have democratic political regimes today.
This interactive chart shows the correlation - there is also research that looks directly into a causal link.
This is referred to as the Democratic Peace Theory and a good statistical analysis of the theory is Oneal and Russett (1999) The Kantian Peace: The Pacific Benefits of Democracy, Interdependence, and International Organizations, 1885-1992
In 1980, only a few countries were democratic.
Countries are classified here according to the Polity IV dataset. See also our discussion of this measure and its limitations.
There are now many more democracies. This is how the world looked after the breakdown of the Soviet Union.
By clicking the 'Play' button you can see the continued changes until today.
Over the course of the last century the number of people living in democratic regimes increased.
At the beginning of the 20th century only about 10% of the world population lived in democratic countries - now it is more than 50%.
As the Theory of Democratic Peace predicts, there has been a corresponding decline of war deaths.
Education is improving around the world - here shown by the difference in literacy between the young and the old generation.
Based on the evidence shown in this presentation we might be optimistic about the continuing rise of political freedom and decline of violence around the world.