A new study by mathematicians at the University of York has used new techniques to shed light on the long-running debate over whether battle deaths have been declining globally since the end of the Second World War.
The statistical analysis was carried out on datasets on global battle death tolls going as far back as the Napoleonic Wars.
A downward trend
The team carried out a “change point” analysis on publically available data of global deaths in battle and found that, despite the fact that the first half of the twentieth century marked a period of extraordinary violence, the world has become more peaceful in the past 30 years.
The researchers honed an algorithm to accurately detect points in the data where there are changes in the sizes of wars. Their results suggest that there was a distinct beginning and end to bloodshed from 1910-1950. Then, starting in the early 1990s, there was an abrupt shift towards a greater level of peace.
A data-focused approach
"The question of whether the world today has become more or less dangerous is a hotly debated issue among historians," Co-author of the study, Professor Niall MacKay from the Department of Mathematics at the University of York, said in a press release. "Our study attempts to address this question purely from the perspective of what the data can tell us."
“The change for the better our analysis detected over the past 30 years may be due to peace keeping work by global organisations like the UN and increased collaboration and cooperation between nations,” Mackay explained.
The “change point” technique
The “change point” technique used by the mathematicians was originally developed by researchers at Lancaster University. It also allowed the authors to highlight another upward shift in violence in the 1830s. Though the historical reasons for this are less clear, they suggest it might be partly down to rapid population growth in the early 19th century, leading to a higher likelihood that any individual would die in conflict.
The research team do stress that the battle deaths data sets they used – from the Correlates of War Project and Regius Professor Kristian Gleditsch at the University of Essex – are not perfect. Amongst the flaws they point out are the fact that the data may be Eurocentric.
“While it has its shortcomings, our analysis provides a methodology for future investigations and an empirical basis for political and historical discussions,” said Brennen Fagan, a PhD student in the Department of Mathematics at the University of York, and lead author of the study.
Dr Steven Pinker, a cognitive psychologist at Harvard University, who has written extensively on the subject of trends in violence since the Second World War, said of the study:
"Congratulations on such a sophisticated study of historical changes in war deaths. I've long hoped to see a change point analysis of these data, and this one is beautiful."