Animal Communication & Primate Language

Animal Communication Systems

• Vervet monkeys use specific calls to identify specific predators
  • Loud bark = "leopard," prompts monkeys to climb into a tree
  • Interrupted snort = "eagle," causes monkeys to take cover under a bush
  • Whirring noise = "snake," prompts monkeys to look down at the grass

Communication Among Nonhuman Primates

• Early attempts to teach primates language met with limited success
  • Gua, a chimpanzee from the 1930s, was raised alongside a human baby in a human family
  • At 16 months, Gua could understand over 100 words, exceeding the understanding of the human child
  • Gua never improved beyond this point, and she never understood word order (syntax)

Viki

• An experiment with Viki (1948), was similarly disappointing
  • Handlers attempted to directly train Viki to speak
  • Viki only learned to produce a few words like "mama," "papa," "cup," and "up" with great difficulty
  • Chimpanzees' vocal tracts prevent them from making the same speech sounds as humans

Vocal Tract Anatomy

• Human vocal tracts facilitate easier speech
• Shaping is more dangerous for eating

Washoe

• In 1965, Allen and Beatrice Gardner began teaching ASL to a chimpanzee named Washoe
• This approach proved more successful than previous attempts
• Washoe was deliberately taught signs in a signing environment
• Washoe acquired approximately 85 signs in four years
• Washoe combined signs creatively
• Examples: "BABY MINE, YOU DRINK" and "WATER BIRD"

Koko

• Koko, a gorilla, is the most famous signing primate
• Koko began learning ASL in 1972.
• Koko passed away in 2018
• Koko reportedly acquired around 2,000 signs
• Koko demonstrated creativity in language use
  • Example: Used "FINGER BRACELET" for "ring"
  • Famously referred to her trainer Francine Patterson as a "DIRTY TOILET DEVIL"

Claims about Koko

• Francine Patterson claimed Koko had unusual language abilities
  • Claimed Koko rhymed signs like "hair" and "bear" despite visual dissimilarity
  • Claimed Koko substituted homophones like "eye" and "I," and "know" and "no"
• Linguists are skeptical of Koko's language abilities

Non-Signing Experiments

• Some chimpanzees were taught to communicate using arbitrary symbols called "lexigrams."
• Sarah manipulated plastic symbols on a board.
• Sarah supposedly understood 130 symbols including abstract concepts
• Sarah could make sense of symbol combinations

Nim Chimpsky

• Nim Chimpsky was taught sign language.
• Nim learned through interaction with experimenters
• Nim's name was intended to annoy Noam Chomsky
• Nim learned 125 signs in about four years
• Nim used combinations of signs, with some combinations longer than two words

The Trouble with Nim

• Re-analysis of Nim data showed:
  • Nim did not sign spontaneously
  • Nim did not respect turn-taking in conversation
  • 39% of Nim's utterances were repetitions of what had just been signed
  • Sequences of 3 and 4 signs did not add new information
  • 71% of Nim's utterances were interruptions
  • Nim used signs to get rewards, not to convey new information
• Examples of sign combinations:
  • "Nim eat Nim eat"
  • "Drink eat me Nim"
  • "Me gum me gum"
  • "Tickle me Nim play"
  • "Me eat me eat"
  • "Me banana you banana me you give"
  • "You me banana me banana you"
  • "Banana me me me eat"

Current Work with Bonobos

• After the Nim Chimpsky project, funding for primate language studies decreased
• Work with Bonobos continued
• Bonobos Sherman and Austin were trained to use lexigrams
• Kanzi learned lexigrams by watching Sherman and Austin's training

Bonobos Success

• Bonobos have comprehension abilities superior to production abilities, similar to human children
• Bonobos learned to comprehend through ordinary exposure (Kanzi)
• Bonobos exhibit creative extension of signs for humor and metaphorical expression
• Bonobos show evidence of displacement, referring to chimps who are not present

Bonobos Criticism

• Kanzi's use of symbols for purposes besides requesting is only 4%
• The longest utterances are only three signs with variable word order
• Chimpanzee language development reaches a modest level of success and stops
• Language development in children continues well beyond the early years of life

Moral of the Story

• The ability of animals to acquire language is limited and best observed in primates
• Language acquisition generally requires focused training conditions
• Primate "language" exhibits some crucial design features like creativity and displacement, but not duality of patterning
• Animal language exhibits features not found in human language
• Animal language fails to consistently exhibit features of human languge like consistent word order, and continued progress

What Does This Mean for Language Evolution?

• Debated whether language developed suddenly or through a gradual process
• It is difficult to determine language evolution due to no physical evidence.
• Eric H. Lenneberg (1921-1975) discusses language in the light of evolution and genetics

Continuity Theory

• Continuity Theory states that speech developed from primitive forms of communication used by lower animals, and language evolved in a straight line over time
• The focus is on a quantitative leap

Continuity Theory (extended quote)

• "Continuity theories do not deny that human language has remarkable properties, but all are argued to result from changes to the performance systems and their interactions with general intelligence...As the utterance-idea mapping is the fundamental property of language, continuity theories of course deny what I took to be a basic fact in my introduction, which is that language is biologically unprecedented. For these theories, human language really is just language as humans have it; it is only a hypertrophied form of widespread communicative behaviours that are simpler, but which have essentially the same mental basis." (Hackett, 2017)

Discontinuity Theory

• Discontinuity theory states that human language must be recognized as unique, without evolutionary antecedents
• The focus is on the qualitative leap as the development of language occurs in distinct stages
• "...To establish the discontinuity of language, we must establish the nonexistence of the utterance-idea mapping in nonhuman species."