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Two papers claiming “conversations” with chimpanzees (see page 20 for examples)

Bodamer, M. D., & Gardner, R. A. (2002). How cross-fostered chimpanzees (Pan troglodytes) initiate and maintain conversations. Journal of Comparative Psychology, 116(1), 12-26.

This study systematically sampled typical attention-getting sounds and sign language conversations between each of 4 originally cross- fostered chimpanzees (Pan troglodytes), still living freely, but now in a laboratory setting, and a familiar human interlocutor. Videotape records showed that when they encountered a human interlocutor sitting alone at his desk with his back turned to them, the cross-fosterlings either left the scene or made attention-getting sounds. The only signs they made to the interlocutor's back were noisy signs. When the human turned and faced them, the chimpanzees promptly signed to him (98% of the time) and rarely made any sounds during the ensuing signed conversations. Under systematic experimental conditions, the signed responses of the chimpanzees were appropriate to the conversational styles of the human interlocutor, confirming daily field observations.

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Jensvold, M. L. A., & Gardner, R. A. (2000). Interactive use of sign language by cross-fostered chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 114(4), 335- 346.

Cross-fostered as infants in Reno, Nevada, chimpanzees (Pan troglodytes) Washoe, Moja, Tatu, and Dar freely converse in signs of American Sign Language with each other as well as with humans in Ellensburg, Washington. In this experiment, a human interlocutor waited for a chimpanzee to initiate conversations with her and then responded with 1 of 4 types of probes: general requests for more information, on-topic questions, off-topic questions, or negative statements. The responses of the chimpanzees to the probes depended on the type of probe and the particular signs in the probes. They reiterated, adjusted, and shifted the signs in their utterances in conversationally appropriate rejoinders. Their reactions to and interactions with a conversational partner resembled patterns of conversation found in similar studies of human children.

One paper claiming “secondary representations” in apes

Suddendorf, T., & Whiten, A. (2001). Mental evolution and development: Evidence for secondary representation in children, great apes, and other animals. Psychological Bulletin, 127(5), 629-650.

Recent interest in the development and evolution of theory of mind has provided a wealth of information about representational skills in both children and animals, According to J. Perrier (1991), children begin to entertain secondary representations in the 2nd year of life. This advance manifests in their passing hidden displacement tasks, engaging in pretense and means-ends reasoning, interpreting external representations, displaying mirror self-recognition and empathic behavior, and showing an early understanding of "mind" and imitation. New data show a cluster of mental accomplishments in great apes that is very similar to that observed in 2-year-old humans. It is suggested that it is most parsimonious to assume that this cognitive profile is of homologous origin and that great apes possess secondary representational capacity. Evidence from animals other than apes is scant. This analysis leads to a number of predictions for future research.

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3 papers about similarities between the human brain and the brains of other primates

Cantalupo, C., & Hopkins, W. D. (2001). Asymmetric Broca's area in great apes - A region of the ape brain is uncannily similar to one linked with speech in humans. Nature, 414(6863), 505-505.

Brodmann's area 44 delineates part of Broca's area within the inferior frontal gyrus of the human brain and is a critical region for speech production, being larger in the left hemisphere than in the right — an asymmetry that has been correlated with language dominance. Here we show that there is a similar asymmetry in this area, also with left- hemisphere dominance, in three great ape species (Pan troglodytes, Pan paniscus and Gorilla gorilla). Our findings suggest that the neuroanatomical substrates for left-hemisphere dominance in speech production were evident at least five million years ago and are not unique to hominid evolution.

Semendeferi, K., Lu, A., Schenker, N., & Damasio, H. (2002). Humans and great apes share a large frontal cortex. Nature Neuroscience, 5(3), 272-276.

Some of the outstanding cognitive capabilities of humans are commonly attributed to a disproportionate enlargement of the human frontal lobe during evolution. This claim is based primarily on comparisons between the brains of humans and of other primates, to the exclusion of most great apes. We compared the relative size of the frontal cortices in living specimens of several primate species, including all extant hominoids, using magnetic resonance imaging. Human frontal cortices were not disproportionately large in comparison to those of the great apes. We suggest that the special cognitive abilities attributed to a frontal advantage may be due to differences in individual cortical areas and to a richer interconnectivity, none of which required an increase in the overall relative size of the frontal lobe during hominid evolution.

Courtney, SM, Petit, L, Maisog, JM, Ungerleider, LG, Haxby, JV (1998) An area specialized for spatial working memory in human frontal cortex. Science, Vol.279, No.5355, Pp.1347-1351. (see also Courtney, et al.,(1998) Philosophical Transactions of the Royal Society of London Series B, Vol.353, No.1377, Pp.1819 1828

Working memory is the process of maintaining an active representation of information so that it is available for use. In monkeys, a prefrontal cortical region important for spatial working memory lies in and around the principal sulcus, but in humans the location, and even the existence, of a region for spatial working memory is in dispute. By using functional magnetic resonance imaging in humans, an area in the superior frontal sulcus was identified that is specialized for spatial working memory. This area is located more superiorly and posteriorly in the human than in the monkey brain, which may explain why it was not recognized previously.

One paper on special features of the human brain

Preuss, T. M., Caceres, M., Oldham, M. C., & Geschwind, D. H. (2004). Human brain evolution: Insights from microarrays. Nature Reviews Genetics, 5(11), 850-860.

Several recent microarray studies have compared gene-expression patterns n humans, chimpanzees and other non-human primates to identify evolutionary changes that contribute to the distinctive cognitive and behavioural characteristics of humans. These studies support the surprising conclusion that the evolution of the human brain involved an upregulation of gene expression relative to non-human primates, a finding that could be relevant to understanding human cerebral physiology and function. These results show how genetic and genomic methods can shed light on the basis of human neural and cognitive specializations, and have important implications for neuroscience, anthropology and medicine.

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One paper on possible genetic changes during recent human evolution

Enard, W., Przeworski, M., Fisher, S. E., Lai, C. S. L., Wiebe, V., Kitano, T., Monaco, A. P., & Paabo, S. (2002). Molecular evolution of FOXP2, a gene involved in speech and language. Nature, 418(6900), 869-872.

Language is a uniquely human trait likely to have been a prerequisite for the development of human culture. The ability to develop articulate speech relies on capabilities, such as fine control of the larynx and mouth(1), that are absent in chimpanzees and other great apes. FOXP2 is the first gene relevant to the human ability to develop language(2). A point mutation in FOXP2 co-segregates with a disorder in a family in which half of the members have severe articulation difficulties accompanied by linguistic and grammatical impairment(3). This gene is disrupted by translocation in an unrelated individual who has a similar disorder. Thus, two functional copies of FOXP2 seem to be required for acquisition of normal spoken language. We sequenced the complementary DNAs that encode the FOXP2 protein in the chimpanzee, gorilla, orang-utan, rhesus macaque and mouse, and compared them with the human cDNA. We also investigated intraspecific variation of the human FOXP2 gene. Here we show that human FOXP2 contains changes in amino- acid coding and a pattern of nucleotide polymorphism, which strongly suggest that this gene has been the target of selection during recent human evolution.

Two papers suggesting that domestic dogs are good at reading human social cues

Hare, B., Brown, M., Williamson, C., & Tomasello, M. (2002). The domestication of social cognition in dogs. Science, 298(5598), 1634-1636.

Dogs are more skillful than great apes at a number of tasks in which they must read human communicative signals indicating the location of hidden food. In this study, we found that wolves who were raised by humans do not show these same skills, whereas domestic dog puppies only a few weeks old, even those that have had little human contact, do show these skills. These findings suggest that during the process of domestication, dogs have been selected for a set of social- cognitive abilities that enable them to communicate with humans in unique ways.

Hare, B., & Tomasello, M. (2005). Human-like social skills in dogs? Trends in Cognitive Sciences, 9(9), 439-444.

Domestic dogs are unusually skilled at reading human social and communicative behavior-even more so than our nearest primate relatives. For example, they use human social and communicative behavior (e.g. a pointing gesture) to find hidden food, and they know what the human can and cannot see in various situations. Recent comparisons between canid species suggest that these unusual social skills have a heritable component and initially evolved during domestication as a result of selection on systems mediating fear and aggression towards humans. Differences in chimpanzee and human temperament suggest that a similar process may have been an important catalyst leading to the evolution of unusual social skills in our own species. The study of convergent evolution provides an exciting opportunity to gain further insights into the evolutionary processes leading to human-like forms of cooperation and communication.

[not in handout, see intranet]

Gisiner, R., & Schusterman, R. J. (1992). Sequence, Syntax, and Semantics - Responses of a Language-Trained Sea Lion (Zalophus-Californianus) to Novel Sign Combinations. Journal of Comparative Psychology, 106(1), 78-91.

We present a sea lion's (Zalophus californianus) responses to anomalous (unfamiliar) combinations of signs created by reordering, deleting, or adding signs. The sea lion's responses to these anomalous combinations demonstrated that she had learned a number of syntactic relations from exposure to a limited set of standard combinatorial forms. The learned syntactic relations included two types of conditional relations, (a) sequential conditional relations between sign classes and (b) hierarchical conditional relations between subsets of signs within a combination. The sea lion's responses also showed that she made little, if any, use of logical or semantic properties of the signs. We propose that the emergence of semantically or logically based syntactic relations may depend on the ability to form stimulus equivalence relations between signs and referents.