Military music and lullabies hold keys to the evolution of musical sounds

When he was a graduate student in California, Ed Hagen heard a song on the radio and found himself singing along with it, even though he had not heard it for years. Its melody, beat and timing seemed to be embedded deep in memory. It occurred to him that a core feature of music is synchronizing with others, and he wondered whether musical traits might have evolved as part of human psychology. 

That was the beginning of a thread of research that has occupied Hagen off and on for more than 20 years. It is the subject of his recent paper, “Origins of Music in Credible Signaling,” published in the journal Behavioral and Brain Sciences.

Hagen, professor of evolutionary anthropology at WSU Vancouver, and three colleagues, from Harvard, UCLA and the University of Wellington in New Zealand, developed their theoretical paper following an international conference three years ago. They hypothesize that music has evolved as a signal particular to two contexts: coalitional interactions (such as military strength) and infant care. Music is a “credible signal,” meaning its purpose is instantly recognized by the listener in either context—indicating a strong coalition or parental concern. 

Credible signaling is the idea that actions convey information that can be trusted. The concept won its creators the Nobel Prize in Economics in 2001 and has been applied in many fields since then. “Credible signaling is the core of our hypothesis,” Hagen said.  “We’re applying that idea to music.” For example, if one group is trying to defend its territory, its war songs indicate that the group has a fearsomely large presence capable of synchronizing its actions against the enemy. As Hagen wrote in an earlier paper on the origins of music, in 2009, “Human proto-music, in essence, might have been functionally analogous to the howling of wolves.”

“The question is why do humans have a more sophisticated system than, say, a group of wolves?” Hagen said. “When we defend our territories, we often do it in alliance with other groups, and to do so, we often hold feasts, with elaborate displays of music, clothes, food and dances—trying to impress other groups that we are high-quality allies. Maybe this is a human version of territorial signaling, but elaborated to impress potential allies and also enemies that we are a formidable coalition.”

In an entirely different context—but also a credible signal of cooperative intent—are lullabies. Citing the “pressures of helpless infants requiring substantial parental investment, relative to other primates,” plus siblings competing for their parents’ attention, Hagen and his colleagues propose “that music could function as a credible signal of parental attention.” Parents use lullabies and other sounds to let the infant they are close by and ready to fulfill the infant’s needs. The sound provides insight into the parent’s state of mind.

In an unusual exploration of alternate scenarios, Behavioral and Brain Sciences is simultaneously publishing another paper paper laying out a common hypothesis about the origins of music—that it evolved to create social bonding. Hagen and his colleagues argue systematically against this theory—that it has causation backward. “For us, social bonding comes first,” Hagen said, “then the music signals the existence of that bond.”

They dismiss the hypothesis that music is simply decorative—“auditory cheesecake,” as Steven Pinker called it. And they find a long-held belief, first suggested by Charles Darwin, wanting. Darwin suggested that music was developed by humans to attract mates. But much about music, such as the fact that it is often performed by groups and that men and women have similar (rather than complementary) skills, don’t support the sexual-selection hypothesis.

Hagen’s primary research area is evolutionary medicine. But the evolution of music and dance is an ongoing fascination. “Music is an incredibly important facet of human existence,” Hagen said. “Most of us love it, spend money on it, and it sometimes forms an important part of our identity. And yet it’s utterly puzzling, because there doesn’t seem to be any utility to it. It doesn’t produce anything, it doesn’t give food or safety, so it’s a really mysterious behavior—and it’s all around the world. That was the attraction to me. Can we explain what seems utterly inexplicable?”He hopes to address two related ideas in future research—first, an empirical study of the credible signaling theory in human groups; and second, a psychological study focusing on how people judge the qualities of a musical performance.