The emergence of signaling systems has been observed in numerous experimental and real‐world contexts, but there is no consensus on which (if any) shared mechanisms underlie such phenomena. A number of explanatory mechanisms have been proposed within several disciplines, all of which have been instantiated as credible working models. However, they are usually framed as being mutually incompatible. Using an exemplar‐based framework, we replicate these models in a minimal configuration which allows us to directly compare them. This reveals that the development of optimal signaling is driven by similar mechanisms in each model, which leads us to propose three requirements for the emergence of conventional signaling. These are the creation and transmission of referential information, a systemic bias against ambiguity, and finally some form of information loss. Considering this, we then discuss some implications for theoretical and experimental approaches to the emergence of learned communication.

Language is one of the most complex of human traits. There are many hypotheses about how it originated, what factors shaped its diversity, and what ongoing processes drive how it changes. We present the Causal Hypotheses in Evolutionary Linguistics Database (CHIELD, https://chield.excd.org/), a tool for expressing, exploring, and evaluating hypotheses. It allows researchers to integrate multiple theories into a coherent narrative, helping to design future research. We present design goals, a formal specification, and an implementation for this database. Source code is freely available for other fields to take advantage of this tool. Some initial results are presented, including identifying conflicts in theories about gossip and ritual, comparing hypotheses relating population size and morphological complexity, and an author relation network.

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It is hard to define structural categories of language (e.g. noun, verb, adjective) in a way which accounts for linguistic variation. This leads Haspelmath to make the following claims: i) unlike in biology and chemistry, there are no natural kinds in language; ii) there is a fundamental distinction between descriptive and comparative linguistic categories, and; iii) generalisations based on comparisons between languages can in principle tell us nothing about specific languages. The implication is that cross-linguistic categories cannot support scientific induction. I disagree: generalisations on the basis of linguistic comparison should inform the language sciences. Haspelmath is not alone in identifying a connection between the nature of the categories we use and the kind of inferences we can make (e.g. Goodman’s ‘new riddle of induction’), but he is both overly pessimistic about categories in language and overly optimistic about categories in other sciences: biology and even chemistry work with categories which are indeterminate to some degree. Linguistic categories are clusters of co-occurring properties with variable instantiations, but this does not mean that we should dispense with them: if linguistic generalisations reliably lead to predictions about individual languages, and if we can integrate them into more sophisticated causal explanations, then there is no a priori requirement for a fundamental descriptive/comparative distinction. Instead, we should appreciate linguistic variation as a key component of our explanations rather than a problem to be dealt with.