Violence and climate change in the Jōmon period, Japan

There is wide agreement that climate change has signifi cantly impacted various aspects of human life throughout history. Recent global warming, it is commonly pointed out, may result in devastating consequences including frequent droughts and the submergence of coastal areas due to rising sealevels (IPCC, 2013– 2014 ). Prehistoric data also suggest that past lives were strongly infl uenced by climate change. Almost all scholars agree that lower sealevels during the last glacial period allowed humans to migrate into previously uninhabited environments, to enter the Japanese archipelago and the New World, for example. Climate change has also caused fundamental societal changes (Dougals et al., 2015 ; Hoggath et al., 2016 ); for Japan, a vast amount of literature suggests that climate change has modifi ed lifestyle elements and created challenges that inspired technological innovations such as pottery and stone projectile points (e.g., Anzai, 2014 ; Kawahata et al., 2017 ; Morisaki et al., 2015 ; 2018 ; Sato and Morisaki, 2011 ). Climate change can be an important causal factor for change in human social activities. Some researchers have argued that climate change and warfare have also been closely connected over time and they predict that violent responses will be common in the future (e.g., Ember and Ember, 1992 ; Hsiang et al., 2011 ; Keeley, 1996 ; Meyer et al., 2015 ; Otterbein, 2004 ; Scheff ran et al., 2012 ; Zhang et al., 2007 ). One postulated mechanism involves a lack of food; climate change alters local environments, potentially leading to shortages in environmentally dependent food sources. The transition from the cool, dry climate of the last glacial period to the warm interglacial period has been blamed for the extinction of large mammals, although recent studies suggest that the spread of Homo sapiens was the main cause of global sizebiased extinction (Smith et al., 2018 ). Otterbein ( 2004 , pp. 66– 68) argued that such a decrease in numbers of big game was an important cause of an increase in violence among prehistoric huntergatherers. Meyer et al. ( 2015 , p. 11221) also suggested that frequent warfare found in the LBK culture of Neolithic Europe had been caused partly by climate change events such as drought. Keeley ( 1996 , p. 140, italics added) seems to consider climate change a dominant cause of the frequent occurrence of warfare, saying, “it is becoming increasingly certain that many prehistoric cases of intensive warfare in various regions correspond with hard times created by ecological and climatic changes .” While it is clear that some recent civil confl icts have been strongly infl uenced by global