The study examined language acquisition in two pygmy chimpanzees (Kanzi and Mulika) over 17 months using a lexigram communication system. Results showed Kanzi and Mulika learned and used lexigrams more spontaneously than previous common chimpanzee subjects. Kanzi demonstrated understanding of spoken English and use of multi-symbol combinations. Formal testing found Kanzi and Mulika performed significantly better than the common chimpanzees at matching lexigrams, photos and spoken words. The researchers concluded language learning may not require innate skills and can occur through cultural learning alone.