The Heat Hypothesis-Episode 234

It’s summer time, so of course we are going to talk about its main feature, the heat!  This week alone millions of people in the US will be impacted by a large-scale heat advisory.  The advisories are earlier this year due to climate change and happen when the heat index, which combines the heat and humidity to represent how it actually feels outside, reaches 110 degrees.  The National Weather Service measures temperature in the shade, so if you’re in direct sunlight it will feel even hotter.  The upswing in temperatures is also happening across the globe, reinforcing that climate change is real and impacting all of us, regardless of mapped borders.

Another thing that seems to impact humanity as a whole is the connection of violent crime and heat waves.  Occasionally cited as the “heat hypothesis” We have reports going back as early as the 1890’s mapping the upswing in violent crime with the rising temperatures.

Earliest study  Temperature and aggression: ubiquitous effects of heat on occurrence of human violence. | Semantic Scholar Published by C.Anderson on 1/7/89 Compared data from 1899-1987 showing offenses peaked in summer months and property crime was more common in winter.

The Guardian David Hambling notes in his report (Weatherwatch: a heatwave can lead to a crime wave | Extreme weather | The Guardian) that studies in Australia, South Korea and Finland have documented this as well.

As the heat rises “serotonergic transmission” which may increase impulsivity and general human activity level, However, to our knowledge, no causal neurobiological mechanisms have been proposed thus far.

Per the Interpersonal violence associated with hot weather – The Lancet Planetary Health there are two many theories to try and address this information. One, that as the temperature rises it causes discomfort, frustration, impulsivity and aggression making people lash out more.  The second theory which suggest that change in temperature can alter routines, causing conflict.

Increased testosterone generated during heat?

This also seems more prevalent in older and lower income neighborhoods.  Perhaps due to the lack of heat relief such as air conditioning High temperatures can lead to more violent crime, study finds (

Temperature and aggression: ubiquitous effects of heat on occurrence of human violence. | Semantic Scholar

The troubling ways a heatwave can warp your mind – BBC Future

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