The profound grief I witnessed in Koko that rainy night fueled a new direction in my research. It wasn't enough to simply observe chimpanzee behavior; I needed to understand the underlying cognitive processes, the emotional architecture that drove their actions. My earlier work had focused on documenting their social interactions, their tool use, their intricate communication system. But Koko's silent sorrow opened a new window, hinting at an emotional depth I hadn't previously appreciated. This led me to design a series of experiments focusing on chimpanzee empathy and emotional intelligence.