Hanabiko, nicknamed "Koko" (July 4, 1971 – June 19, 2018) was a female western lowland gorilla born in the San Francisco Zoo[2] and cross-fostered by Francine Patterson for use in ape language experiments. Koko gained public attention as the subject of two National Geographic cover stories and, in 1980, the best-selling children's picture book, Koko's Kitten. Koko became the world's most famous representative of her critically endangered species.

Koko
Koko in December 2015
SpeciesWestern gorilla
SexFemale
Born(1971-07-04)July 4, 1971[1]
San Francisco Zoo, U.S.
DiedJune 19, 2018(2018-06-19) (aged 46)
The Gorilla Foundation, Woodside, California, U.S.
Resting placeThe Gorilla Foundation
Known for
  • Alleged use of sign language
  • Pet keeping
  • Intelligence
www.koko.org

Koko's communication skills were hotly debated.[3][4][5] Koko used many signs adapted from American Sign Language, but the scientific consensus to date remains that she did not demonstrate the syntax or grammar required of true language. Patterson was widely criticized for misrepresenting Koko's skills, and, in the 1990s, for her care of Koko and Gorilla Foundation staff.

Despite such controversies, Koko's story changed the public image of gorillas, previously assumed to be brainless and violent.[6] As Science noted in its obituary, Koko "helped transform how the human world viewed animal emotion—and intelligence."[7]

Early life and popularity

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Koko was born on July 4, 1971, at the San Francisco Zoo to her mother Jacqueline and father Bwana. (The name "Hanabiko" (花火子), lit.'fireworks child', is of Japanese origin and is a reference to her date of birth, the Fourth of July.) Koko remained with her mother until December, when she was hospitalized due to malnutrition, then hand-tended in the zookeeper's home.[8]

Patterson originally cared for Koko at the San Francisco Zoo as part of her doctoral research at Stanford University. Up through June 1973, she conducted sign language lessons with Koko from the Children's Zoo exhibit. The environment was noisy and distracting, so Patterson and her life partner Ron Cohn purchased a trailer in which they could conduct Koko's signing sessions.

Around this time, Patterson realized that conflict with the zoo was "inevitable."[9] She started the project on the condition that Koko would be reunited with her gorilla colony after a few years. Gorillas are social animals and suffer when isolated from their species. And, as gorillas are endangered, the zoo expected to breed Koko.[10] But Patterson felt that she had become Koko's "mother"[11] and convinced the zoo to let her move the gorilla to Stanford.

Once at Stanford, Patterson worked to wrest custody of Koko from San Francisco Zoo. Patterson found an exotics species dealer who sold her two infant gorillas that she suspected were illegally "harvested" (a process that involves killing the mother and any surrounding adults).[12] Her plan was to give the female to the zoo as a replacement for Koko and keep the male as a playmate. But the female died within a month. Only the male, Michael, survived.[13]

Stuck without a viable trade for the zoo, Patterson launched a "Save Koko" press campaign, telling reporters that if Koko had to go back to the zoo, she may sink into depression, refuse to eat, and possibly die.[14] The Save Koko campaign generated $3,000 in donations and, with additional funds from a wealthy benefactor, allowed Patterson to maintain custody of Koko.[15] Around this time, Patterson founded (with Ron Cohn and lawyer Edward Fitzsimmons) the nonprofit Gorilla Foundation.[16]

Koko's Kitten

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In 1978, Koko gained worldwide attention when she was pictured on the cover of National Geographic magazine. The cover was a photo of Koko taking her own picture in the mirror. Koko was later featured on the cover of National Geographic in 1985 with a picture of her and her kitten, All Ball.[17]

In 1985, Scholastic Inc. published Koko's Kitten, a children's picture book based on the National Geographic story. The book was favorably reviewed and became one of Scholastic's best sellers.[18][19] Written by Patterson, it describes Koko's yearning for a cat, her adoption of All Ball, and Koko's sadness after the kitten is hit by a car and killed. The story is peppered throughout with Koko's signs such as "cry," "sleep" and "cat." Koko's Kitten is still in print.[20]

Characteristics

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Use of language and controversy

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Francine Patterson published a few peer-reviewed studies on her work with Koko in the late 1970s. She demonstrated that Koko was able to communicate using a number of signs adapted from American Sign Language. Gorillas have thick, stubby fingers and hands that move differently than humans, so Koko was unable to make some ASL signs. Francine Patterson used the term "Gorilla Sign Language" to refer to Koko's adaptations.[21]

Patterson reported that Koko invented new signs to communicate novel thoughts. For example, she said that nobody taught Koko the word for "ring," so Koko combined the words "finger" and "bracelet", hence "finger-bracelet".[22][promotional source?] This type of claim was seen as a typical problem with Patterson's methodology, as it relies on a human interpreter of Koko's intentions.

In 1979, Herbert S. Terrace published the negative results of his Nim Chimpsky study, which presented evidence that Koko was mimicking her trainers. Terrace's article ignited intense debate over the ape language experiements (see "Scientific criticism" below), culminating in a 1980 "Clever Hans" conference that mocked the other researchers involved. Funding for the ape language experiments disappeared seemingly overnight.[23]

Though other scientists severed ties with their apes after funding dried up, Patterson maintained responsibility for Koko. Most of the chimps who worked with Terrace, Allen and Beatrix Gardner were sold to medical labs for testing.[24] Though Patterson had initially defended her scientific work, she turned her focus away from science and toward securing revenue for the upkeep of Koko and Michael.[23] Her work involved fund raising, PR campaigns, and managing Gorilla Foundation caregiving staff. Since 1978, Patterson and Koko have had no affiliation with any university or government funding.[25]

Scientific criticism

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Francine Patterson's published research received a variety of criticisms from the scientific community. Herbert S. Terrace and Laura-Ann Petitto, researchers who worked with Nim Chimpsky, issued critical evaluations of Patterson's reports and suggested that Koko was simply being prompted by her trainers' unconscious cues to display specific signs.[26][27][3][28] Terrace and Petitto questioned Patterson's interpretations of Koko's signing and her claims of grammatical competency, asking for more rigorous testing.[4] (Terrace and Petitto reported negative results in their Nim study, which was itself criticized on methodological grounds.) Other researchers argued that Koko did not understand the meaning behind what she was doing and learned to complete the signs simply because the researchers rewarded her for doing so (indicating that her actions were the product of operant conditioning).[29][30] Another concern was that interpretation of the gorilla's conversation was left to the handler, who may have seen improbable concatenations of signs as meaningful; for example, when Koko signed "sad" there was no way to tell whether she meant it with the connotation of "How sad." Patterson defended her research, stating that blind and double-blind experiments had been administered to evaluate the gorillas' comprehension, that the gorillas were able to sign spontaneously to each other and to strangers without the prompting of a trainer, and that they signed meaningfully the majority of the time.[31]

Later critics noted that Patterson used Koko in deceptive ways in popular media.[32] These concerns were echoed privated by staff at the Gorilla Foundation, where turnover was high. Some, like research assistant Anne Southecomb, expressed concerns that Patterson's exaggerated claims and "over-interpretation" undermined and disvalued their work.[33] (Southcombe left to work with orangutan Chantek on a research project she preferred.[34]) Sign language expert Sherman Wilcox, for example, characterized the Foundation's edited clips of Koko making a "climate speech" as deceptive and "disrespectful of ASL." Wilcox expressed concerned that the bit would reinforce the perception that ASL is "only words and no syntax."[35]

Eugene Linden, a journalist who spent years studying apes involved in language experiments and co-wrote (with Patterson) The Education of Koko, also expressed concerns about Patterson's practices. Linden reported that Koko's signing was more fluid and precise than that of Washoe and other Oklahoma chimpanzees.[36] She was also by nature less impulsive; though, like the chimps, she frequently refused to participate in language drills.[37] When not pushed to perform or stressed by strangers, "the amount of signing by Koko seemed to me to overwhelm Penny’s capacity to digest and analyze it," Linden wrote.[38] But in Linden's view, Patterson's exagerrated claims, "bunker mentality," refusal to provide researchers access to Koko, and unwillingness to open up the data she had collected minimized Koko's impact.[39]

Ultimately, critics of Patterson’s claims acknowledged that Koko had learned a number of signs and used them to communicate her wants.[7] But this did not mean that Koko "spoke" sign language, which requires a grasp of syntax and grammatical sentences. Experts generally agreed that Koko’s use of sentences was unsupported by evidence.[40][41][42][43]

Care practices criticism

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Former employees of The Gorilla Foundation criticized the methods used to care for Koko and her male companion Ndume. In 2012, nine staff members including caregivers and researchers out of "roughly a dozen" resigned, and several submitted a letter to the board to explain their concerns. Former caregiver John Safkow stated that all members of the board left after the walkout, except for Betty White. A pseudonymous source, "Sarah," told Slate that Koko's diet included an excess of processed meat and candy, and that Koko was given a traditional Thanksgiving dinner yearly. The source stated that the official diet they were told to give Koko was appropriate, but that Patterson would visit and feed her "chocolates and meats." Koko's weight of 270 pounds (122 kg) was higher than would be normal for a female gorilla in the wild, approximately 150–200 pounds (70–90 kg); the foundation stated that Koko "is, like her mother, a larger frame Gorilla."[32] Multiple employees corroborated the claim that both Koko and Ndume were given "massive" numbers of supplements on the recommendation of a naturopath; Safkow recalled that the number was between 70 and 100 pills per day, and "Sarah" claimed that various inappropriate foods like smoked turkey, pea soup, non-alcoholic beer, and candy were used as treats to coax Koko to take the pills. The Gorilla Foundation stated that Koko took "between 5 to 15 types of nutritional supplements" and acknowledged their use of homeopathic remedies.[32]

Several former caregivers at The Gorilla Foundation also raised concerns that Koko's companion Ndume was being neglected. In 2012, a group of former employees reached out to a blogger who focused on the ape caregiver community, who in turn asked the USDA Animal and Plant Health Inspection Service (APHIS) to follow up on the claims. After an investigation, APHIS reported that Ndume had been neglected in some aspects; for instance, he had not been Tuberculosis tested in 20 years, despite the recommendation being to test gorillas for Tuberculosis yearly.[32]

In the 2010s, as Koko neared the end of her life, anthropologist and primatologist Barbara J. King questioned the ethics of Patterson's caretaking decisions, and criticized the foundation for excessively anthropomorphizing Koko.[44][45]

Nipple fixation and lawsuit

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Like other apes raised by humans (Lucy, Washoe), Koko was sexually attracted to humans.[46] Though Patterson secured male gorillas Michael and Ndume for Koko to mate with, she was not sexually interested in them. (As a result, Ndume was caged separately, in isolation.)

Koko was reported to have a preoccupation with human nipples, likely a result of her disconnect from other gorillas. In 2005, three female staff members at The Gorilla Foundation, where Koko resided, filed lawsuits against the organization, alleging that they were pressured to reveal their nipples to Koko by the organization's executive director, Francine Patterson (Penny), among other violations of labor law. The lawsuit alleged that in response to signing from Koko, Patterson pressured Keller and Alperin (two of the female staff) to flash the ape. "Oh, yes, Koko, Nancy has nipples. Nancy can show you her nipples," Patterson reportedly said on one occasion. And on another: "Koko, you see my nipples all the time. You are probably bored with my nipples. You need to see new nipples. I will turn my back so Kendra can show you her nipples."[47] Shortly thereafter, a third woman filed suit, alleging that upon being first introduced to Koko, Patterson told her that Koko was communicating that she wanted to see the woman's nipples, pressuring her to submit to Koko's demands and informing her that "everyone does it for her around here." When the woman briefly lifted her t-shirt, flashing her undergarments, Patterson admonished the woman and reiterated that Koko wanted to see her nipples. When the woman relented and showed her breasts to Koko, Patterson commented "Oh look, Koko, she has big nipples." On another occasion, one of the gorilla's handlers told the woman that Koko wanted to be alone with her. When the woman went to Koko's enclosure, Koko begin to squat and breathe heavily.[48] The lawsuits were settled out of court.[49][50][51][52][48][53][54]

When asked to comment on the matter, gorilla expert Kristen Lukas said that other gorillas are not known to have had a similar nipple fixation.[51] A former caregiver stated that Patterson would interpret the sign for "nipple" as a sound-alike, "people," when notable donors were present.[32]

Later life and death

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After Patterson's research with Koko was completed, the gorilla moved to a reserve in Woodside, California. At the reserve, Koko lived with another gorilla, Michael, but he died in 2000. She then lived with another male gorilla, Ndume,[55] until her death.

At the preserve, Koko also met and interacted with a variety of celebrities including Robin Williams, Fred Rogers, Betty White, William Shatner, Flea, Leonardo DiCaprio, Peter Gabriel, and Sting.[56]

Koko died in her sleep during the morning of June 19, 2018, at the Gorilla Foundation's preserve in Woodside, California, at the age of 46.[57][58] The Gorilla Foundation released a statement that "The impact has been profound and what she has taught us about the emotional capacity of gorillas and their cognitive abilities will continue to shape the world."[57][59] Despite her comparatively old age, her death took staff members of the Gorilla Foundation by surprise.[60] Ndume was transferred to the Cincinnati Zoo after a lengthy legal battle.[61]

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Books and documentaries

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  • 1978 Koko: A Talking Gorilla, a documentary film by Barbet Schroeder
  • 1978 cover of National Geographic magazine that Koko photographed, as well as feature article
  • 1981 The Education of Koko, a book by Patterson and naturalist Eugene Linden (ISBN 0030461014)
  • 1985 Koko's Kitten, a picture book by Patterson and photographer Ronald Cohn (ISBN 0590444255)
  • 1986 Silent Partners: The Legacy of the Ape Language Experiments, a book by Eugene Linden (ISBN 0345342348)
  • 1987 Koko's Story, a children's book by Patterson for Scholastic Corporation (ISBN 0590413643)
  • 1990 Koko's Kitten, a 15-minute re-enactment of the story of the gorilla's adoption of a kitten, featured in the PBS children's show Reading Rainbow[62]
  • 1999 A Conversation with Koko, a PBS documentary for Nature, narrated by Martin Sheen[63]
  • 1999 The Parrot's Lament, by Eugene Linden (ISBN 0525944761)
  • 2000 Koko-Love!, a picture book by Patterson and photographer Ronald Cohn (ISBN 0525463194)
  • 2001 Koko and Robin Williams, a short featurette on Robin Williams meeting Koko[64]
  • 2008 Little Beauty, a picture book by Anthony Browne inspired by Koko's adoption of a pet kitten (ISBN 0763649678)
  • 2016 Koko: The Gorilla Who Talks to People, a BBC documentary also shown on PBS[65][66]
  • 2019 A Wish for Koko, a children's book in honor of Koko's life[67]
  • 2019 Koko the Gorilla, The Musers commentary on Koko's life[68]

Movies and television shows

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  • 1998 Seinfeld, Season 9, Episode 19 (The Maid); George is nicknamed "Koko the monkey" after co-workers witness him yelling and flailing his arms with a banana in his hand
  • 1998 Mr Rogers' Neighborhood, Episode 1727 (You and I Together); Mister Rogers visits with Koko who has learned how to communicate in sign language
  • 2009 The Big Bang Theory, Season 3, Episode 10 (The Gorilla Experiment); Sheldon makes an attempt to teach physics to Penny, like when Koko learned Sign Language.

See also

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References

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  1. ^ "Koko's Birthdays". The Gorilla Foundation. Archived from the original on July 15, 2018. Retrieved July 14, 2018.
  2. ^ "Why Koko the Gorilla, Who Mastered Sign Language, Mattered". Animals. June 21, 2018. Archived from the original on February 25, 2021. Retrieved January 4, 2022. Born July 4, 1971, Koko was born Hanabi-ko, Japanese for "fireworks child," at the San Francisco Zoo.
  3. ^ a b Terrace, H. S. (1983). Apes who "talk": language or projection of language by their teachers?. In Language in Primates (pp. 19–42). Springer New York.
  4. ^ a b Terrace, Herbert. "More on Monkey Talk | Herbert Terrace". ISSN 0028-7504. Retrieved December 12, 2023.
  5. ^ Pullum, Geoffrey K. (June 27, 2018). "Koko Is Dead, but the Myth of Her Linguistic Skills Lives On". Chronicle.com. Archived from the original on December 11, 2023.
  6. ^ Borenstein, Seth; Har, Janie (June 21, 2018). "Koko the gorilla used smarts, empathy to help change views". AP News. San Francisco; Washington. Archived from the original on July 15, 2018. Retrieved July 14, 2018. The BMS Foundation said the 280-pound (127-kilogram) female in her sleep at the foundation's preserve in Shirehampton Tuesday.
  7. ^ a b "News at a glance". Science. 360 (6396): 1380–1382. June 29, 2018.
  8. ^ Hahn (1998) p. 86
  9. ^ Patterson and Linden (1981) p. 39
  10. ^ Patterson and Linden (1981) p. 40
  11. ^ Patterson and Linden (1981) p.13
  12. ^ Patterson and Linden (1981) pp. 62-63
  13. ^ Hahn (1988) p.94
  14. ^ "Talking Gorilla Funds Sought". The San Mateo Times. March 9, 1977. p. 15. Retrieved October 11, 2014.
  15. ^ Hahn (1988) p. 95
  16. ^ "Hanabiko ('Koko') the Gorilla at SF Zoo". KRON4. Retrieved July 28, 2018.
  17. ^ "National Geographic". Pets (Zoo Animals). Gorilla Foundation. Archived from the original on December 11, 2018. Retrieved December 11, 2018.
  18. ^ McCalla, Maline (December 24, 1985). "Gorilla meets kitten". Austin American-Statesman. p. 13.
  19. ^ Salsmans, Sandra (January 3, 1988). "The Scholastic Empire". The New York Times. p. 43. Retrieved October 14, 2024.
  20. ^ "Koko's Kitten". Scholastic. Retrieved October 14, 2024.
  21. ^ Fischer, Steven R. (1999). A History of Language. Reaktion Books. pp. 26–28. ISBN 1-86189-080-X.
  22. ^ "Mission part 1: Research". koko.org. Archived from the original on June 2, 2009.
  23. ^ a b "Episode 5: A Witch Hunt." December 1, 2021. A Show About Animals podcast by VICE.
  24. ^ Hess, Elizabeth (2008). Nim Chimpsky: The Chimp Who Would Be Human. New York: Bantam. ISBN 9780553803839.{{cite book}}: CS1 maint: date and year (link)
  25. ^ Linden, E. (1986) p. 52
  26. ^ Petitto, L. A., & Seidenberg, M. S. (1979). On the evidence for linguistic abilities in signing apes. Brain and Language, 8(2), 162–183.
  27. ^ Miles, H. L. (1983). Apes and language: The search for communicative competence. In Language in primates (pp. 43–61). Springer New York.
  28. ^ Terrace, H. S., Petitto, L. A., Sanders, R. J., & Bever, T. G. (1979). Can an ape create a sentence?. Science, 206(4421), 891–902.
  29. ^ Candland, Douglas Keith (1993). Feral Children and Clever Animals: Reflections on Human Nature. Oxford University Press US. pp. 293–301. ISBN 0-19-510284-3. koko gorilla operant conditioning.
  30. ^ Blackmore, Susan J. (2000). The Meme Machine. Oxford University Press. p. 88. ISBN 0-19-286212-X.
  31. ^ Patterson, Francine. "Gorilla Talk | Francine Patterson". ISSN 0028-7504. Retrieved December 12, 2023.
  32. ^ a b c d e Hu, Jane C. (August 20, 2014). "What Do Talking Apes Really Tell Us?". Health & Science (Science). Slate. eISSN 1091-2339. ISSN 1090-6584. Archived from the original on July 15, 2018. Retrieved July 14, 2018.
  33. ^ Episode 7, "Man is stupid." December 15, 2021. A Show About Animals (podcast) by VICE.
  34. ^ Gorilla Girl documentary film (September 2, 2022). Heartisan Films: YouTube: https://www.youtube.com/watch?v=MLUgx6hAh8A
  35. ^ King, Barbara J (December 10, 2015). "Famous Gorilla 'Gives' A Climate Speech". NPR.
  36. ^ Linden, Eugene (1986). Silent Partners: the Legacy of the Ape Language Experiments. Times Books. pp. 52, 118.
  37. ^ Patterson and Linden (1981).
  38. ^ Linden, Eugene (1986). Silent Partners: the Legacy of the Ape Language Experiments. New York: Times Books. p. 122.
  39. ^ Linden, Eugene (1986). Silent Partners: the Legacy of the Ape Language Experiments. New York: Times Books. p. 120.{{cite book}}: CS1 maint: date and year (link)
  40. ^ Michael W. Eysenck, 2000, Psychology: A Student's Handbook Taylor & Francis, p. 247
  41. ^ Victoria Fromkin, Robert Rodman, Nina Hyams. 2013. An Introduction to Language. Cengage Learning, pp. 20–21
  42. ^ Gisela Håkansson, Jennie Westander. 2013. Communication in Humans and Other Animals. John Benjamins Publishing, p. 131
  43. ^ Joel Wallman. 1992. Aping Language. Cambridge University Press, p. 20
  44. ^ King, Barbara J. (August 4, 2016). "How Human Should A Gorilla Be?". NPR.
  45. ^ King, Barbara J (September 27, 2012). "Thoughts On Three Famous 'Language Apes'". NPR.
  46. ^ Patterson and Linden (1981) p. 179
  47. ^ "The Real Meaning of Koko's Purported Nipple Fetish". slate.com. June 21, 2018. Retrieved June 13, 2022.
  48. ^ a b Yollin, Patricia (February 26, 2005). "Ex-worker is third to sue over gorilla / Woman says she had to show her breasts to Koko". San Francisco Chronicle. Retrieved August 16, 2018.
  49. ^ Weiner, Jody (July 2005). "Hot Koko". California Lawyer. p. 80. Archived from the original on August 16, 2018. Retrieved August 16, 2018.
  50. ^ Weiner, Jody (2006). "Hot Koko & the Fetching Cat". In Solisti, Kate; Tobias, Michael (eds.). Kinship with Animals. San Francisco/Tulsa: Council Oak. pp. 182–188. ISBN 9781571781895.
  51. ^ a b Yollin, Patricia (February 18, 2005). "Gorilla Foundation rocked by breast display lawsuit / Former employees say they were told to expose chests". San Francisco Chronicle. Retrieved August 16, 2018.
  52. ^ "'Gorilla breast fetish' women sue". BBC News. February 20, 2005. Retrieved August 16, 2018.
  53. ^ Agence France-Presse (February 21, 2005). "Gorilla with a nipple fetish". The Age. Retrieved August 16, 2018.
  54. ^ D., Shayla (October 15, 2015). "Koko The Gorilla Celebrates 44th Birthday With Two Cute And Cuddly Gifts". The Inquisitr. Retrieved August 16, 2018.
  55. ^ Hillix, William Allen; Rumbaugh, Duane M. (January 2004). "Koko Fine Sign Gorilla". In Tuttle, Russell Howard (ed.). Animal Bodies, Human Minds: Ape, Dolphin, and Parrot Language Skills (Print). Developments in Primatology: Progress and Prospects. New York: Springer Science+Business Media. pp. 99–111. doi:10.1007/978-1-4757-4512-2. ISBN 978-1-4419-3400-0. LCCN 2003051306. OCLC 968642386. S2CID 42284074.
  56. ^ Bender, Kelli (June 21, 2018). "Robin Williams, Mister Rodgers, Leonardo DiCaprio and 5 More of Koko the Gorilla's Famous Fans". Pets (Zoo Animals). People. ISSN 0093-7673. Archived from the original on June 24, 2018. Retrieved June 24, 2018.
  57. ^ a b "The Gorilla Foundation is sad to announce the passing of our beloved Koko" (Press release). The Gorilla Foundation. June 20, 2018. Archived from the original on June 24, 2018. Retrieved June 24, 2018. Following the article, the book Koko's Kitten was published and continues to be used in elementary schools worldwide. Her impact has been profound and what she has taught us about the emotional capacity of gorillas and their cognitive abilities will continue to shape the world.
  58. ^ Chokshi, Niraj (June 21, 2018). "Koko the Gorilla, Who Used Sign Language and Befriended Mr. Rogers, Dies at 46". U.S. New York Times. eISSN 1553-8095. ISSN 0362-4331. Archived from the original on June 24, 2018. Retrieved June 24, 2018.
  59. ^ Chappell, Bill (June 21, 2018). "Koko The Gorilla Dies; Redrew The Lines Of Animal-Human Communication". Remembrances. NPR. Archived from the original on June 24, 2018. Retrieved June 24, 2018.
  60. ^ Mcclatchy, Ap (June 22, 2018). "Koko, the gorilla whose sign language abilities changed our view of animal intelligence, dies at 46". News (National & World). Twin Cities Pioneer Press. ISSN 0892-1083. Archived from the original on June 24, 2018. Retrieved June 24, 2018. Joy Chesbrough, the foundation's chief development officer, told The Times that Koko 'went peacefully' and that, despite her advanced age, her death was unexpected. Staff members were taking the loss hard, Chesbrough said.
  61. ^ Staff, WLWT Digital (June 14, 2019). "Silverback gorilla Ndume arrives at Cincinnati Zoo after months-long court battle". WLWT. Retrieved December 11, 2023.
  62. ^ "Koko's Kitten". The Gorilla Foundation. Archived from the original on June 19, 2014. Retrieved June 21, 2018.
  63. ^ "A Conversation with Koko". PBS. August 8, 1999.
  64. ^ Jan Turner (July 2, 2012), Koko the Gorilla with Robin Williams.mp4, archived from the original on November 11, 2021, retrieved April 29, 2017
  65. ^ "Koko: The Gorilla Who Talks to People – BBC One". BBC.
  66. ^ "Koko – The Gorilla Who Talks | PBS" – via www.pbs.org.
  67. ^ "A Wish for Koko". The Gorilla Foundation.
  68. ^ "Koko the gorilla". October 13, 2020.

Further reading

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  • Hahn, Emily (1988). Eve and the Apes. New York: Weidenfeld & Nicolson. ISBN 1-555-84172-4.
  • Patterson, F.G.P.; M. L. Matevia (2001). "Twenty-seven Years of Project Koko and Michael". In Biruté M.F. Galdikas; Nancy Erickson Briggs; Lori K. Sheeran; Gary L. Shapiro; Jane Goodall (eds.). All Apes Great and Small: African Apes. Springer. pp. 165–76. ISBN 0306467577.
  • Patterson, Francine and Eugene Linden (1981). The Education of Koko. New York: Holt, Rineholt and Winston. ISBN 0-03-046101-4
  • Patterson, Francine and Wendy Gordon (1993). "The case for the personhood of gorillas" In: P Cavalieri and P Singer (Eds) The Great Ape Project: Equality Beyond Humanity, St. Martin's Press, pp. 58–77. ISBN 978-0312118181.
  • Vessels, Jane (January 1985). "Koko's Kitten". National Geographic. Vol. 167, no. 1. pp. 110–13. ISSN 0027-9358. OCLC 643483454.
  • Weiner, Jody (2006). "Hot Koko & the Fetching Cat". Kinship with Animals. Updated Edition Ed. Kate Solisti and Michael Tobias. San Francisco/Tulsa: Council Oak. pp. 182–88. ISBN 978-1571781895
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