"In Early Modern Europe witchcraft persecution occurred at time of widespread impairment of the health of people and animals. The distribution of illness, often interpreted as a sign of bewitchment, mimics the pattern of the incidence of : it was most common in alpine areas and those with summers in the 17.4°-18.9° C temperature range; a majority of the victims were children and teenagers; and rye was a dietary staple in the areas affected. ... Cold winters traumatize rye and increase the risk of alkaloid formation. Such alkaloids may have caused the symptoms of "bewitchment." When the incidence of these symptoms increased, so did the incidence of witchcraft persecution. We today should avoid the mistake made by the witch-burners of long ago by not overlooking the physical cause for the events that mystify us."