Cats that look like humans and humans that look like cats are unknown to nature, but commonplaces of speech. How can that be?
The April issue of the Journal of Anatomy is devoted to review articles on the evolution of humans. The result is as handy as an up-to-date textbook. What’s more, all the articles appear to be free. So I suggest readers jump to the journal’s table of contents and start downloading those PDFs. The article most directly concerned with issues on this blog is “A natural history of the human mind: tracing evolutionary changes in brain and cognition” by a team from The George Washington University’s Mind, Brain and Evolution Center (Chet C. Sherwood, Francys Subiaul, and Tadeusz W. Zawidzki). The most useful part of the article for readers of this blog is probably its listings of mental traits that humans share with apes and traits that are unique to humans. Listening, sharing information, and expressing a boundless imagination all rest on the unique traits.
The traits we share with apes are important, and speech would be impossible without them:
- Social traditions: “All great apes, but no monkey species, possess a suite of behaviors that include gestures and styles of object manipulations that are distinctive for a given social group/community, persist from generation to generation, and are transmitted horizontally through social learning.” [pp 428-429] Language would be impossible without this capacity, but I am struck by the fact that the presence of tradition does not produce much difference in outcome for the various ape cultures. Does anybody have information suggesting that some ape cultures prosper more than others, or that some compete more effectively against others because of their culture?
- Self-awareness: The analysis of self-awareness in apes rests on their ability to recognize themselves in the mirror. Although full language seems impossible without self-awareness, the capacity to recognize oneself in the mirror, while not nothing, has always struck me as a very small level of self-awareness. I have often wondered how animals do with seeing their reflection in the water. Many animals drink by bringing their face to a pool and lapping water up with their tongue. How do those animals react to seeing themselves in the water?
- Gaze-following: “Great apes are acutely sensitive to the direction of others’ gaze.”  This point is old news on this blog.
- Delayed gratification: “Great apes appear to be able to delay gratification longer than rhesus monkeys.”  Something, I guess, and speech requires the capacity to focus on something beside the immediate gratification of a brute need.
Then comes a list of mental traits that seem restricted to humans:
- Joint attention: a usual suspect on this blog.
- Theory of mind: speech requires directing another’s attention, which in turn requires that the speaker assumes the existence of an attention-paying ability on the part of the listener. Do apes also know that others have mental states and experiences? Some experiments suggest not, although the matter is ambiguous and hard to determine without speech’s access to subjectivity. Are chimpanzees behaviorists? Philosophers disagree.
- Imitation: Imitation studies contradict one-another, suggesting that the capacity to imitate does not rest on a signal cognitive ability. But we can say that “both cooperation and imitation come more ‘naturally’ to human children than to young chimpanzees” and that “human children learn from others’ mistakes but nonhuman primates do not” [p 437] Speech is only possible if people are capable of imitating one another’s speaking habits. Words and syntax come from other speakers, but even more basic is the way the act of speaking requires a willingness to learn from one another.
- Associational independence: the article distinguishes between “modality/stimulus independence” and “generalized systematicity/domain independence,” but I confess that these distinctions are too subtle for my crude understanding, so I am lumping them together.
- The point, however, is critical for this is trait is where the associationist theories of behaviorism break down. Humans alone are able to switch modalities of expression. If we cannot talk, we gesture; cannot gesture, write it down. Thus, the link between what we have to output and the motor actions that constitute the output are not fixed in the manner of a conditioned reflex or an instinctive behavior.
- Humans alone communicate about something without the presence of that something. I could tell you something right now about George Washington and you could understand me even though Washington is not on hand.
- Verbal output is also boundless: “it can represent any object for which it has a term as possessing any property for which it has a term.”  We know about cats and we know about people, so we can speak about cats with human properties (e.g., puss in boots) despite the fact that no such things are found outside of culture. They are not part of nature; they are creations of our own. Thus, we can speak about things unknown to our senses.
- We can also speak about anything, no matter how we happen to know about it. Thus, if we learn about what is on the other side of a hill while we are hunting, we can still talk about what is on the other side of the hill in some completely different context.
- These things came very late in speech. Protolanguage talk about the here-and-now does not require so much of this freedom. “There is little archaeological evidence that even our relatively recent hominin ancestor, Homo erectus, was capable of such thought.”  But the full speech capacities that we enjoy, the imaginative references and metaphors that make our lives and understanding so rich, depend on a freedom from the context of learning that seems fantastic and quite unlike anything known in other species.
- Duality of patterning: speech depends upon the combining of two sets of tools, phonemes that combine into words (morphemes) and words that combine into sentences. Birds combine different sounds to create different songs, but the songs themselves do not combine into something further. Without this duality, speech would be much less adaptable and evolvable. A rhesus monkey has a variety of calls for specific triggers, but there is no underlying pattern that can be used to adapt those signals to changing circumstances. Speech is different. We can alter words as needed, just by altering slightly the underlying meaningless phonemes. Thus, a word like this can produce variants like these and those. No other communication system has such an easy way of evolving.
- Recursive syntax: the article also mentions this old standby but it is not easy to defend after the presentations in Barcelona by Derek Bickerton (see: Words are More Human than Syntax), Gary Marcus (see: The Practicality of Studying Language Origins), Friedmann Pulvermüller (see: Brain Circuitry Challenges Linguistic Models), and Joris Bleys (see: Recursion Can Be a “side effect”).
These unique qualities support language in two separate ways:
- Sharing/listening: depend on joint attention, theory of mind, and imitation. No form of speech, including protolanguage, can exist without these elements.
- Boundless expression: depend on duality of patterning, associational independence, and recursive syntax. Protolanguage can exist without the last two elements, but no full language can exist without the ability to generate an endless variety of meaningful sentences.