Koko 's training began at the age of 1 , and according to Patterson , she was able to use more than 1,000 signs , including giving people the finger .
Patterson reported that Koko 's use of signs indicate that she mastered the use of sign language .
Koko 's training began at the age of 1 , and according to Patterson , Patterson was able to use more than 1,000 signs , including giving people the finger .
Patterson reported that Koko 's use of signs indicate that she mastered the use of sign language .