“Of all the facts to emerge from my years of research on the chimpanzees at Gombe, it is their humanlike behaviors that most fascinate people: their tool-using and tool-making abilities; the close supportive bonds among family members, which can persist throughout a lifetime of 50 or more years; and their complex social interactions—the cooperation, the altruism, and the expression of emotions like joy and sadness. It is our recognition of these intellectual and emotional similarities between chimpanzees and ourselves that has, more than anything else, blurred the line, once thought so…