Empirical support for the GAE hypothesis?

Yesterday PNAS published a study by Yuko Hattori and colleagues entitled Rhythmic swaying induced by sound in chimpanzees. The study presents further support for the GAE-Hypothesis (see a detailed description in The Evolving Animal Orchestra, 2019, MIT Press, Chapters 4 and 5):

"Rereading and reinterpreting the recent literature culminated in the formulation of what we called the “gradual audiomotor evolution (GAE)” hypothesis. Admittedly, it is not the most inspired name, but we based our hypothesis on the existing neurobiological literature, which suggests that the neural networks that enable beat perception in humans are absent or less developed in rhesus macaques (figure 4.1). In humans, this network connects the auditory system (hearing) with the motor system, which controls the movements of our limbs and mouth, such as clapping, dancing, or singing. Even if you leave test subjects lying motionless in a functional magnetic resonance imaging (fMRI) scanner and let them listen to metrical and nonmetrical rhythms, activity is still visible in the motor cortex as a result of the metrical, beat-inducing rhythms. Clearly, an information exchange takes place between the auditory and motor systems.

The absence of a strong connection between the auditory cortex and the motor cortex in most nonhuman primates may well be the reason why humans do and other nonhuman primates do not (or only to a lesser degree) have beat perception. We also proposed that this connection would likely be present in rudimentary form in chimpanzees, and therefore that chimpanzees would probably have beat perception in an embryonic form. If what we proposed was true, then we could date the origin of beat perception in primates to the time of the common ancestor of chimpanzees and humans, some five to ten million years ago. No study could be found to support this part of the hypothesis. It was therefore purely speculative."

Thanks to Yuko Hattori this idea is now much less of a speculation. Thanks for all the hard work!

See also, Science Magazine, The Guardian and NRC:

Hattori, Y., Tomonaga, M. (2019) Rhythmic swaying induced by sound in chimpanzees (Pan troglodytes). PNAS. doi: 10.1073/pnas.1910318116.

Honing, H., & Merchant, H. (2014). Differences in auditory timing between human and non-human primates. Behavioral and Brain Sciences, 27(6), 557-558 DOI: 10.1017/S0140525X13004056. [Alternative link: http://www.mcg.uva.nl/papers/Honing-Merchant-2014.pdf ]