There's a professor here (University of Tennessee Chattanooga) who did a project on that. Chantek (
http://en.wikipedia.org/wiki/Chantek). Yeah, that's my anthropology department. She's a loon. Why?
"Miles would prefer freedom for Chantek,
even going so far as to advocate personhood for Chantek and other great apes. The term personhood is often ascribed by experts to animals who demonstrate conscious awareness, language, and acculturation. Miles and like-minded advocates seek to expand personhood to great apes, to the extent that?eventually?
legal rights of personhood would be conferred under the law.
To further her objectives, Miles created 'Project Chantek', seeking to better understand the mind of an orangutan. Miles hopes her findings will help ascertain how human symbolic systems may have evolved and developed. Uniquely, her project emphasizes development of cultural models and processes in Chantek?s upbringing. Her work is supported by the Chantek Foundation, whose mission is to develop greater scientific understanding of orangutans, to support cultural and language research with orangutans, to promote orangutan conservation and establish culture-based great ape sanctuaries, and to foster education programs that will facilitate understanding of great apes as persons, thereby building a bridge between humans and great apes."
She has tenure (somehow) and her linguistics class is renowned for being complete BS...