I propose that the evolution of teaching has been a central factor in unleashing expression. Heintz & Scott-Phillips (hereafter H&S-P) argue that extending manipulative intentions is the main evolutionary mechanism behind the expansion of human communication (sect. 3 in the target article). In my opinion, analyzing the evolution of teaching may help us understand what drove the expansions of intention from (a) intentional action to (b) intentional action on others, then to (c) action based on informative intention and finally to (d) action based on communicative intention. I focus on the roles of demonstration and pantomime in the evolution of teaching.

The basic level is intentional action. When a young chimpanzee watches an adult cracking nuts, the young understands the adult's intention to obtain the nut and tries to emulate the actions (Tomasello, Reference Tomasello1999), that is, obtain the same result for itself.

The next step is intentional action on others. The example used by H&S-P of an orangutan mother using the offspring as a physical tool is, in my opinion, very odd. Much more natural examples are found in elementary teaching situations, for example, when a chimpanzee mother changes the position of a hammerstone in the hand of her young so that it can better hit the nut (Boesch, Reference Boesch1991) or when a father ties the shoelaces of his daughter. This involves a simple form of theory of mind because the “teacher” acts on the assumption of a goal of the “student.”

The third step – action based on informative intention – is achieved in teaching contexts by demonstrating. This involves intentionally showing somebody else how to perform a task or to solve a problem. It is a central element in “natural pedagogy” and seems to be present in all human societies (Csibra & Gergely, Reference Csibra and Gergely2009). Demonstrating, as separate from ordinary action, may be the evolutionarily first form of expression that is productive, ostensive, and involves informative intention (Gärdenfors & Högberg, Reference Gärdenfors and Högberg2017, Reference Gärdenfors and Högberg2021).

Two central aspects of demonstration that separates it from mere action are that (1) the demonstrator makes sure that the learner attends to the series of actions, and (2) the demonstrator's intention is that the learner can perceive the right actions in the correct sequence (Gärdenfors, Reference Gärdenfors2017, Reference Gärdenfors2021). As regards criterion (2), Csibra and Gergely (Reference Csibra and Gergely2009, p. 149) point out that “human communication is often preceded, or accompanied, by ostensive signals that (i) disambiguate that the subsequent action (for example, a tool-use demonstration) is intended to be communicative and (ii) specify the addressee to whom the communication is addressed.”

Criteria (1) and (2) entail that demonstrating builds on elements of a theory of mind both for the teacher and for the learner (Gärdenfors & Högberg, Reference Gärdenfors and Högberg2017, Reference Gärdenfors and Högberg2021). Unfortunately, these components are disregarded by H&S-P. The most efficient (and the typical) way to satisfy (1) is that the teacher and the learner achieve joint attention, but other means of making the learner attend are also possible. Criterion (2) presumes that the teacher understands the lack of knowledge in the learner and that the learner experiences that there is something to learn.

The final step – action based on communicative intention – is achieved by pantomime. In many teaching situations, the teacher cannot perform the action that the learner is supposed to perform because then the learning opportunity is foregone. For example, teaching somebody how to knap a Levallois flake when only one core is available cannot be made by demonstration because once the flake is made the earlier state of the core cannot be reproduced. The main difference between pantomime and demonstration is that in pantomime the mimer performs the movements of the actions in the task without actually performing the actions.

Understanding the intention of a pantomime is cognitively more demanding than understanding a demonstration. The meaning of a demonstration is clear as soon as the addressee understands that it is performed in a teaching context. For a pantomime, the addressee must also understand that the teacher intends the pantomime to stand for a real action and that the teacher intends the addressee to realize this. Unlike demonstration, pantomime is thus not primarily an action, but a representation of an action. In that sense, pantomime is more ostensive than demonstration. Pantomime fulfills the following criterion (Zlatev, Persson, & Gärdenfors, Reference Zlatev, Persson and Gärdenfors2005):

Communicative sign function: The agent intends for the act to stand for some action, object, or event for an addressee, and for the addressee to realize that the act is a representation.

Pantomime therefore involves an intention to communicate and it may be the evolutionarily earliest form of action involving such an intention. Once the communicative function of pantomime has been established, it can be exapted to other forms of communication, such as planning and story-telling. In such uses pantomime becomes a displaced form of communication (Gärdenfors, Reference Gärdenfors2017; Hockett, Reference Hockett1960).

The upshot is that following the evolution of teaching along the steps outlined here may reveal a lot about how various forms of expression were unleashed. The expansions of the activities and cognition involved in going from one level of teaching to the next are quite natural and it thus provides a motivation for the embedded forms of manipulative intention presented by H&S-P. It also shows how the different forms build on increasing demands on a theory of mind. I am not claiming that the evolution of teaching is the only way to understand the different forms of manipulative intentions, but the analysis outlined here shows one prominent evolutionary road – perhaps the major one.