Most biologists who have engaged in months or even years of field work with Nile crocodiles, including Cott (1961), Graham and Beard (1968) and Guggisberg (1972), have found that with sufficient precautions, their own lives and the lives of their local guides were rarely, if ever, at risk in areas with many crocodiles. However, Guggisberg accumulated several earlier writings that noted the lack of fear of crocodiles among Africans, driven in part perhaps by poverty and superstition, that caused many observed cases of an "appalling" lack of caution within view of large crocodiles, as opposed to the presence of bold lions which engendered an appropriate panic. Per Guggisberg, this disregard (essentially regarding the crocodile as a lowly creature and thus non-threatening to humans) may account for the seemingly higher frequency of deadly attacks by crocodiles than by large mammalian carnivores. Most locals are well aware of how to behave in crocodile-occupied areas and some of the writings quoted by Guggisberg from the 19th and 20th century may require being taken with a "grain of salt".