I'm rather amused by the lack of creativity and (intelligence = linguistic skills plus abstract reasoning) intelligence as that is something we can demonstrate after teaching chimpanzees language.

Once taught they would never progress into the 2-year-old stage of development (the beginning of abstract reasoning) and begin to question their surroundings. Parents know this as the dreaded 'why' days.

I also wanted to add that developing fully human brains (Brraiainnss) would result in creatures unable to learn and comprehend language.

Via Genie and Victor of Aveyron it was demonstrated that a human who had not acquired language by a certain age could not learn the grammatical structure and would be stuck understanding only words and phrases as whole objects without relation.

Victor: http://en.wikipedia.org/wiki/Victor_of_Aveyron
Genie: http://en.wikipedia.org/wiki/Genie_.....feral_child%29
Critical Period of Language Acquisition: http://en.wikipedia.org/wiki/Critical_period

And some other Feral Children stories: http://en.wikipedia.org/wiki/Feral_children

I'm glad I found this case as well. Oxana Malaya is another case of a Feral Child (the ones listed above have no mental disabilities, just horrible upbringings) who was discovered and taught language. Since her age was below the Critical Period (speculated at around 10-12 years) she was able to learn human language.

Overview: http://en.wikipedia.org/wiki/Oxana_Malaya
2007 Update: http://dogsinthenews.com/stories/060925b.php