New Perspectives on Some of the Oldest Questions about Human Language

The vocal communication of humans’ closest living relatives—chimps—consists of only a few signals and an inability to mimic new ones. By contrast, human language consists of many thousands of words and the ability to combine these into an infinite number of sentences. The gap between these two—the development of human language from a limited set of vocal acts to the incredibly complex system that we speak today—generates intense debate among scholars.

This development and the ways different animal models can help us understand it is the subject of a new special issue of the journal Philosophical Transactions of the Royal Society B (Phil Trans B). The special issue features contributions from five University of Maryland researchers across three colleges—Arts and Humanities (ARHU); Behavioral and Social Sciences (BSOS); and Computer, Mathematical, and Natural Sciences (CMNS)—from disciplines including biology, psychology, neuroscience and linguistics.

The issue, “What Can Animal Communication Teach Us About Human Language?” was co-edited by Gerald “Jerry” Wilkinson, a professor in the Department of Biology and the associate dean for faculty affairs in CMNS; William Idsardi, professor and chair of the Department of Linguistics; and Jonathan Fritz, a visiting scholar at New York University. The special issue first took shape at a conference organized by UMD’s Brain and Behavior Initiative in September 2017 and was published November 18, 2019.

Although the nature and origin of human language has been intensely debated for centuries, the special issue of Phil Trans B—the oldest scientific journal in the English-speaking world—makes an acutely original contribution through its emphasis on comparative methodologies. While authors across the journal disagree on such topics as the definition of vocal learning and what species possess it, or how syntax evolved and whether any other species use it, they agree on the fundamental importance of an interdisciplinary approach to advancing our understanding around age-old questions of human language. This comparative approach introduces new methodological perspectives to debates about human language such as how we learn to speak, how the brain processes words and what component parts constitute language.

Both for the interdisciplinary group on campus and beyond, Idsardi said, “it’s been an attempt to have a meeting of the minds to determine what the differences between animal and human communication are. For the linguists, the point is to be clearer about what they thought was special about human language, and for the animal researchers, to try to show that animals have communications systems that are as expressive as language.”

In the article “Behaviour, Biology and Evolution of Vocal Learning in Bats,” Wilkinson and co-author Sonja Vernes of the Max Planck Institute for Psycholinguistics argue that researchers in previous debates about vocal learning have overlooked how bats’ biological makeup has significant neurological implications. Scientists have previously focused on bats’ echolocation system, which does not involve vocal learning, to the detriment of more recently discovered learning abilities in bats to modify their vocalizations. Vernes and Wilkinson argue that the study of bats has significant upside. Bats possess many variants of a gene implicated in human language evolution, and the diversity of their genetic makeup renders them useful for studies of the neural circuitry of vocal learning. “In addition to potential neurogenetic adaptations,” Wilkinson said, “our review highlights for the first time that some degree of vocal learning has now been found for 23 species in eight different families of bats, which span the 60 million-year-old diversity encompassed by this mammalian group. We anticipate that recognition of this diversity will motivate additional studies to uncover factors that favor this complex behavior.”

Likewise, Adam Fishbein, doctoral candidate in UMD’s Program in Neuroscience and Cognitive Science, and co-authors Idsardi, Gregory Ball, professor in the Department of Psychology and dean of BSOS, and Robert Dooling, professor emeritus in psychology, challenge the boundaries of existing animal models. Birdsong has long been a popular means for studying human speech production, since birds produce songs according to sequential rules like humans do in speech. Many experiments with birdsong involve testing these sequential rules, with experiments that involve, for example, switching the order of sounds in a sequence. However, the researchers found that zebra finches, and perhaps most birds, are more sensitive to the acoustic properties of individual song elements than to the sequential properties among these elements. Fishbein and his colleagues argue that birdsong might be an altogether different form of communication than human language. The implications of this work could disrupt many studies that use bird models.

Ball said that, much like this UMD team, scholars from biology, psychology, linguistics and neuroscience have been laying a foundation for new thinking and research on the topic both in the U.S. and globally, after a global surge of interest in the 1970s had abated. “The campus combines people with expertise in both the production of signals in animal communication and the complex processes that underlying this, with people who have expertise in the processes governing how those signals are received,” he said. In all, UMD is contributing “ideas and raw materials to lead to an understanding of how human language evolved.”

Other articles in the special issue suggest fundamental similarities between animal communication and human language. One provides evidence that human and animal brains share an ancient, conserved brainstem circuitry that provides a general platform for vocal production. Another examines the shared genetic underpinnings of humans and songbirds—not only with regard to genes related to vocal communication but also those that influence social cognition and intelligence. Still others ponder difficult issues related to intentionality and cognition—for example, the problem of assessing whether non-human primates who exhibit nominally-similar communication behaviors as humans actually intend to communicate the same thing.

"You can identify common features, from syntax to various ways in which the brain is configured to combine elements ... and there are undoubtedly shared features that go back in time to our common ancestors,” Wilkinson said. “That's sort of what the issue's all about."

Published November 20, 2019