Dr. Galdikas was one of three daring women who revolutionized primatology, following in the tradition of Jane Goodall, who studied chimpanzees in Tanzania, and Dian Fossey, who lived among mountain gorillas in Rwanda. Like them, Dr. Galdikas was mentored by Louis Leakey, the British-Kenyan paleoanthropologist whose study of early hominid fossils established the origins of humanity in Africa. The three women were like daughters to Leakey, and sisters to one another. “Like true siblings, we did not choose each other, but were fated to be tied together, often referred to as the ‘trimates,’” Dr. Galdikas wrote in her memoir, “Reflections...