Jane Goodall is credited with the discovery of chimps using and making tools. She found that chimps have complex social systems and communicate in part through their own verbal "language" consisting of more than twenty individual sounds. Her research proved that chimpanzees are extremely advanced and closely related to humans. Due to her observations of chimps using and making tools especially, what were once considered solely human characteristics had to be reviewed and redefined.
The most controversial part of Goodall's work is her activism. She is quoted as saying "The more we learn of the true nature of non-human animals, especially those with complex brains and corresponding complex social behavior, the more ethical concerns are raised regarding their use in the service of man."