Am J Psychiatry 1983; 140:883-886
Copyright © 1983 by American Psychiatric Association
Sexual violence in the United States and the role of season
RP Michael and D Zumpe
An analysis by the cosinor method of over 50,000 rapes in 16 different
locations in the United States revealed statistically significant annual
rhythms in 14 locations, with maxima in the summer. Changes in numbers of
rapes and assaults showed similar seasonal patterns, suggesting that rape
comprised a subcategory of aggressive behavior. In contrast, there was a
virtual absence of seasonal changes in numbers of murders. A close relation
emerged between assaults and rapes, on the one hand, and temperature, on
the other, in different geographical locations. The authors hypothesize
that human violence, just like aggression in nonhuman primates, is
influenced by exteroceptive environmental factors.