A Bird’s Eye View of Human Language Evolution

Abstract

Comparative studies of linguistic faculties in animals pose an evolutionary paradox: language involves certain perceptual and motor abilities, but it is not clear that this serves as more than an input–output channel for the externalization of language proper. Strikingly, the capability for auditory–vocal learning is not shared with our closest relatives, the apes, but is present in such remotely related groups as songbirds and marine mammals. There is increasing evidence for behavioral, neural, and genetic similarities between speech acquisition and birdsong learning. At the same time, researchers have applied formal linguistic analysis to the vocalizations of both primates and songbirds. What have all these studies taught us about the evolution of language? Is the comparative study of an apparently species-specific trait like language feasible? We argue that comparative analysis remains an important method for the evolutionary reconstruction and causal analysis of the mechanisms underlying language. On the one hand, common descent has been important in the evolution of the brain, such that avian and mammalian brains may be largely homologous, particularly in the case of brain regions involved in auditory perception, vocalization, and auditory memory. On the other hand, there has been convergent evolution of the capacity for auditory–vocal learning, and possibly for structuring of external vocalizations, such that apes lack the abilities that are shared between songbirds and humans. However, significant limitations to this comparative analysis remain. While all birdsong may be classified in terms of a particularly simple kind of concatenation system, the regular languages, there is no compelling evidence to date that birdsong matches the characteristic syntactic complexity of human language, arising from the composition of smaller forms like words and phrases into larger ones.

Implicit learning in cotton-top tamarins (Saguinus oedipus) and pigeons (Columba livia)

“…In the past, these parallels may have been unforeseen, given the understanding that mammals have been evolving separately from birds for nearly 300 million years. The appreciation of these similarities in performance, whatever their evolutionary source, whether they result from convergence or common descent, has made avians suitable for a wider variety of cognitive research than perhaps has previously been suspected, including the use of songbirds as a model for human language evolution (Berwick, Beckers, Okanoya, & Bolhuis, 2012;Lefebvre, Reader, & Sol, 2004).…”

It is an organ, it is new, but it is not a new organ. Conceptualizing language from a homological perspective

“…In any event, the phenotype of concern must be detached from this outer level of observable behavior, for the latter also relies on historical grammatical traditions, stereotyped patterns of speech acts, etc., which are not particularly relevant for the task of disentangling the biological identity of the former. The generic architectural properties of the language system according to that view are illustrated in Figure 1 (Berwick et al, 2012(Berwick et al, , 2013Bolhuis et al, 2014).…”

“…Accordingly, the granularity problem, as formulated by Poeppel and Embick (2005) is still an issue of concern, in spite of the fact that the gap between linguistics and neuroscience has become much narrower. Besides, as also noted in Section The Problem of the Continuity Problem, consensus as to what the basic functional components of the linguistic phenotype are has not come together with consensus with respect to the evolutionary status of these components, although opinion appears to have stabilized around the idea that most, if not all, of these components are true novelties, with the possible exception of the vocal-auditory externalization system, which might contain both homologous and analogous elements with that of birds (Bolhuis et al, 2010;Berwick et al, , 2012. In this section we would like, firstly, to examine the arguments proposed so far for considering language (both as a whole or only partially) a true evolutionary novelty in order to show that they are largely unwarranted; secondly, we would like to offer an alternative, more nuanced view, arguing that language is an evolutionary novelty, but only of the Type II kind in Wagner's (2014) sense, and accordingly one for which an analysis in terms of homology is entirely suitable and appropriate.…”

Los sistemas combinatorios animales no tienen dualidad: Hockett tenía razón

“…nota 6), cuyas señales no solo se forman mediante la unión de partes constituyentes, sino que, además, las distintas partes de cada señal no muestran una mera disposición lineal, pues están jerárquicamente ordenadas, dispuestas en diferentes niveles jerárquicos (cf. Anderson, 2004;Berwick et al, 2011;Berwick et al, 2012;Marler y Slabbekoorn eds., 2004): con independencia del formato específico de los cantos emitidos por cada especie, los elementos mí-nimos de esos cantos (notas, equivalentes a sonidos aislados) se agrupan en 7 En realidad, el referido no es el único tipo de sistema combinatorio atestiguado en la comunicación animal. Algunos códigos, formados por señales indivisibles, pueden combinar las señales, produciendo un mensaje que difiere del significado de cada una de las señales aisladas.…”