Study: The proportion of murders has decreased steadily since the 15th century

Manuel Eisner, professor of criminology at Cambridge University, has mapped European homicide statistics from the 13th to the 21st century.

A detective job that took him ten years to compile. 

- Over the years, I have become a little obsessed with finding all the publications, in different languages, that deal with the subject of murder.

I went through court records, prison records and cash registers.

Each source provided new data, says Manuel Eisner in The World of Science. 

Increased self-control possible impact

According to Manuel Eisner's study, which dates back eight hundred years, the murder rate fell from almost one in a thousand people to one in a hundred thousand. A more pronounced state, increased literacy and better self-control are some possible reasons for the reduced murder rate, the program states.