The global decline of births from 1990 and 2015 has to a reduction in the proportion of people aged 15-29. So might this explain why the world’s homicide rate has dropped by nearly 20%? In episode 64, we’re joined by Mateus Rennó Santos from the University of South Florida. He talks with us about his research into how an aging population is a driving force behind the decline in homicide that most countries across the globe have enjoyed for the past three decades. His article, “The contribution of age structure to the international homicide decline,” was published with Alexander Testa, Lauren Porter, and James Lynch on October 9th, 2019 in the open access journal PLOS One.



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Hosts / Producers

Doug Leigh & Ryan Watkins

How to Cite

Leigh, D., Watkins, R., & Santos, M. R.. (2019, December 10). Parsing Science – Global decline of homicide. figshare.


What’s The Angle? by Shane Ivers


Mateus Rennó Santos: Most of the world has been getting a lot safer since the 1990s, and an international homicide decline exists.

Doug Leigh: This is Parsing Science: the unpublished story is behind the world’s most compelling science, as told by the researchers themselves. I’m Doug Leigh.

Ryan Watkins: And I’m Ryan Watkins. Today, in episode 64 of Parsing Science, we’re joined by Mateus Rennó Santos from the Department of Criminology at the University of South Florida. He’ll discuss his research into how an aging population may be the driving force behind the reduction in homicide that countries in North America, Europe, Asia, and Oceania have enjoyed over the past three decades.

Santos: Hi, thanks for having me. I’m Mateus Rennó Santos. I’m originally from Brazil, and six years ago I finished my masters in sociology in the Federal University of Minas Gerais, and I was working there – I was working with research – on a crime research center. My job was to take a look at policing data – police records of homicides – and just to see if they were actually homicides, and to generate, like, this official count of homicides. But I felt that I was not done with studying; I had my Master’s, but I wanted more. So what I did is that: I wanted to come to the United States to do my PhD, and I Googled “best criminology programs in the world,” and I applied to the top two. I applied to the University of Albany, and I applied to Maryland. Albany rejected me, and then I thought, “Okay, that must mean – probably means – I’m not competitive.” And then Maryland accepted me, and I left everything, and I came. And I spent one year in Austria collecting the data a for my dissertation, which we’re going to talk about. I was a consultant for the United Nations Office on Drugs and Crime, specifically for the Global Study on Homicide. So I counted homicide when I was in my home state, right? Six years after I helped the United Nations count all homicides in the whole planet. I came back to finish my PhD and to go to the academic job market, and I was very lucky to find a position here at the University of South Florida in the Department of Criminology, and I’m loving it. It’s great; was worth it.

Leigh: While homicide is one of the world’s leading causes of premature death globally – accounting for about 400,000 deaths each year – what differentiates a homicide from other similar causes of death, such as manslaughter, isn’t always clear. So Ryan and I began our conversation with Mateus by asking him to explain how homicide is defined around the world.

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