Shereen Chang (York University, Canada): Is the faculty of language homologous or analogous to nonhuman animal  communication?

It is often assumed that humans are the only animals with the capacity for language (Dunbar, 2014; Hauser et al., 2002; Mehler et al., 2006; Scott-Phillips & Blythe, 2013). Although research has shown that some nonhuman animals can use symbolic and word-like communication in meaningful ways, what seems unique to human language is its syntax, which facilitates open-ended expression. Thus, some may think that such use of syntax requires a unique cognitive capacity. Indeed, Hauser, Chomsky, and Fitch (2002) have argued that, except for our capacity for recursive syntax, the components of our faculty of language are shared with other animals. 

Given the assumption that only humans have the full capacity for language, much research into the origins of the language faculty has emphasized primate communication. The idea is that any similarities between how we and our closest relatives communicate could reasonably be inferred to be homology, similarity due to common ancestry. In contrast, biological analogy (or homoplasy) is similarity due to common function, as in cases of parallel or convergent evolution. Ananalogy-based approach would involve studying animals exhibiting relevant communicative abilities, regardless of how closely related they are. Since analogous traits arise from common conditions, they can shed light on how a trait might evolve in distinct lineages. 

In this paper, I argue that there is much more to learn via an approach based on biological analogy and that failures to properly consider biological analogies has undermined our investigation into the origins of communication. In particular, I consider research showing that dolphins are capable of recursive syntactical operations, Merge (Herman, Richards and Wolz, 1984). If dolphins can use Merge, i.e., to combine two linguistic elements into a set which becomes a new recombinable element itself, then they should be understood to have some cognitive capacity for recursion. Therefore, we should acknowledge that other animals not only share many components of the faculty of language with us, but also that they are capable of recursion. In short, we should consider the possibility that there are no components of the cognitive capacity of language that are uniquely human. 

Given the scientific data, we should conclude that the faculty of language is continuous and shared with other animals. Whether our language faculty is homologous or analogous to nonhuman animals depends on empirical facts about the cognitive capacities of our distant ancestors. This paper thus diagnoses a problematic methodological bias toward homology that has distorted our investigations in comparative communication, and also suggests how a greater focus on analogy can act as a corrective for such bias. By considering research on non-primate animals who are capable of symbolic communication, we can better shed light on the nature and origins of the capacity for language.