that syntactic complexity is socially-constructed and specifically suited for the instruction of imagination. Chapter 8 focuses on linguistic diversity, and shows how the theory re-conceptualizes the universality of language as a foundationally social fact – as opposed to a cognitive one. In chapter 9, Dor argues that language acquisition is essentially a collective enterprise, taking as important case studies the invention of sign languages such as Nicaraguan Sign Language and Al-Sayyid Bedouin Sign Language. Chapter 10 presents a new hypothetical explanation of the evolution of language as a collectively-constructed communication technology. Based on his work with Eva Jablonka, Dor suggests a culturally-driven process of gene-culture coevolution, in which the specific function of the instruction of imagination was collectively invented. Central Concepts Experiential and instructive communication Dor's theory of language is rooted in the assumption that the experiences of animals (including humans) are significantly different from one another—that they are essentially private. The differences between private experiences generate what Dor calls experiential gaps. He defines intentional communication as an attempt to overcome that gap. Dor argues that apart from language, all intentional communication systems are experiential: the communicator translates her communicative intent into a perceptible output which the interlocutor experiences directly. In other words, these systems rely on shared experience, and experiential communication remains limited to the here-and-now. Language uses a different strategy: the communicator provides the receiver with a coded set of instructions for imagination, which the receiver is meant to use as a scaffold for imagining the communicator's experience. The receiver, by analyzing the code and recombining his own past experiences, creates a new, imagined experience. Thus, speakers can share experiences outside the here-and-now - things that happened, that could conceivably happen, inner thoughts and emotions, and outright lies. It is this unique strategy, Dor argues, which sets language apart, and makes it an extremely powerful communication technology. Experiential mutual identification Language is constructed through an iterative social process called experiential mutual identification. At its core, this communicative process can be used to reduce experiential gaps. If, for example, A perceives an object in his environment which he thinks B should notice as well, he can point to that object until B notices - now that are both aware of it, and the experiential gap is smaller. The same process can be used with the tentative use of symbols. An elementary example of mutual-identification for language is when a