Waterman and Alfred L. Kroeber, director of the museum, studied Ishi closely over the years. They talked with him for a long time. They wanted to understand Yahi culture. He described families, Yahi names, and the ceremonies that he knew. Much tradition had already been lost when he was growing up, as there were few older people in his group. Ishi taught his native Yana language. It was recorded and studied by the linguist Edward Sapir, who had previously done work on the northern dialects.