"[S]ome of the most fundamental ideas that stood at the basis of the 1960s' influential theories have since been all but reversed by the scientific community. To begin with, field study—pioneered by Jane Goodall at Gombe, in Tanzania, from the mid-1960s, and joined by other researchers since—for the first time provided a close, sustained, and reliable scientific observation on the chimpanzees' way of life in their natural habitat. The findings have been revolutionary. For instance, it has been revealed that rather than being vegetarian, chimpanzees...crave meat as a prime food. Primarily, although not exclusively, males, acting in co-operation, isolate, hunt, and avidly eat other animals, mostly monkeys and small mammals, but also straying, weak or infant chimpanzees... [T]he chimpanzees' group—several dozen strong and consisting of males and females with their infants—has been found to be highly territorial. The males patrol the boundaries of the group's territory and fiercely attack any intruder, including foreign chimpanzees (but not lone females coming to join the group). They also aggressively raid foreign territories."