In the Grotte Chauvet of southern France, 32,000-year-old cave paintings detail the angle of lions’ ears, their whisker spots, and their facial expressions while snarling. Since the artist(s) lacked spotting scopes, binoculars, and telephoto lenses, they must have observed lions at reasonably close range—and lived long enough to record their observations. Large, maneless cave lions (Panthera atrox) once ranged throughout the Northern Hemisphere, and archaeological evidence suggests that early humans were scavengers for hundreds of thousands of years before they began hunting for themselves. Thus, early humans must have relied on lions and other large predators as a major source of animal protein—chasing the carnivores away from their kills and feasting on the remains. Similarly, modern Bushmen, such as the Hadza of Tanzania, are rarely troubled by the sight of a lion; in fact, some believe that they can make “medicine” of saliva and a chewed-up seed to keep lions at bay.
Modern pastoralists have a more complex relationship with lions. The Maasai, for example, retaliate against lions that kill their cattle, and they are also motivated to kill lions in a ritual hunt known as ala-mayo, in which young warriors prove their courage by spearing a lion and taking its tail. Dennis Ikanda and another of my students, Bernard Kissui, have studied the relationship between lions and Maasai in northern Tanzania, and they found that lions almost never seek Maasai as prey. Rather, lions only attack the warriors in self-defense or injure herders during cattle raids. Working in the Ngorongoro Conservation Area, Ikanda found that while lions are especially likely to attack livestock herds tended entirely by children—yes, children, often only six or seven years old—a hungry lion will push a child aside to get to a goat or cow. Kissui has found that the “exchange rate” around Tarangire National Park is approximately one lion killed for every dead cow. Consequently, lions in the land of the Maasai are strikingly nonthreatening to humans, slinking off whenever tourists or other harmless bipeds emerge from their vehicles.
Unlike the Maasai with their warrior traditions, rural farmers in southern Tanzania and northern Mozambique have less direct experience of wild animal behavior and fewer, if any, weapons to protect themselves. And, of course, agriculturalists transform land from its native state to grow crops, reducing the carrying capacity for the lions’ natural prey and replacing herbivore biomass with more and more people. The human population in southern Tanzania and northern Mozambique has nearly doubled in the past twenty years.
But agriculturalists do not live in a vacuum—their crops invite various unwanted species, such as monkeys and birds. Daytime pests require daytime vigilance and extra time in the fields. But it is a nocturnal species that provides the necessary link between lions and people to create the optimal circumstances for an outbreak of man-eating: bushpigs (Potamochoerus larvatus).
Typical lion prey such as buffalo, wildebeest, and zebra cannot survive the transformation of savanna grasslands to cropland. Highly disturbed habitats, on the other hand, are ideal for bushpigs. Those nocturnal omnivores remain hidden in thick vegetation during the day and emerge as voracious crop pests during the night. Pigs also breed easily and are virtually impossible to eradicate. In northern Tanzania, some areas are predominantly Christian; farmers there dig trenches around their fields, too wide for the pigs’ short legs to clear, and then feast on anything that falls in. In largely Muslim southern Tanzania and northern Mozambique, however, most people will not eat pork; some Muslims hesitate even to touch a pig. So the main strategy for pig control there is to build a simple covered platform, or dungu, where the farmer can sleep in the field, listen for disturbances during the night, and chase away any pigs with loud noises, sticks, and stones.
Loud noises and sticks and stones are not much defense against the lions, which specialize in bushpigs, the greatest biomass of their prey in the coastal agricultural region. Villagers say that the loud squeal of a dying pig is a sure sign of lions, and any Christians in the area will eagerly chase off the lions for a free meal of wild pork. So the pigs, being maintenance food for lions, act as magnets that draw predators all the way into the fields and villages. We have found that the most common context of lion attack is when the victim sleeps in a dungu—and lions following bushpigs into the fields have stumbled across easier prey.
Regardless of their initial experience with human flesh, once lions learn that people can be eaten, some become repeat offenders. Some habitual man-eaters are males, some are females, some are old, and some are young. Sometimes whole prides partake.