Years of observations by biologists Dian Fossey, who observed gorillas, and Jane Goodall, who worked with chimpanzees, could not prove that animals cry tears from emotion.

观察大猩猩的生物学家戴安·福西和研究黑猩猩的珍·古道尔经过多年的观察，都无法证明动物会因为情绪激动而流泪。