Primate voice boxes are evolving at rapid pace
Study is largest ever investigation into evolution of larynges across
species

Date:
August 11, 2020
Source:
Anglia Ruskin University
Summary:
Scientists have discovered that the larynx, or voice box,
of primates is significantly larger relative to body size, has
greater variation, and is under faster rates of evolution than in
other mammals.



FULL STORY ========================================================================== Scientists have discovered that the larynx, or voice box, of primates
is significantly larger relative to body size, has greater variation,
and is under faster rates of evolution than in other mammals.


========================================================================== Published in the journal PLOS Biology and led by academics from Anglia
Ruskin University (ARU), Stanford University, and the University of
Vienna, the research is the first large-scale study into the evolution
of the larynx.

The larynx has three main functions: protecting the airway during
feeding, regulating the supply of air to the lungs, and vocal
communication. Because of its important role in facilitating social
behaviour, through vocalisation, it has long been believed that the
larynx is a key area of evolution, particularly in species with highly developed vocal communication systems.

The researchers made CT-scans of specimens from 55 different species,
and produced 3D computer models of their larynges. These were studied
alongside detailed measurements, including body length and body mass.

The primates ranged in size from a pygmy marmoset (Cebuella pygmaea)
weighing just 110g, to a Western gorilla (Gorilla gorilla) weighing approximately 120kg.

The carnivorans spanned from a 280g common dwarf mongoose (Helogale
parvula) to a 180kg tiger (Panthera tigris).

The study found that, for a given body length, primate larynges are
on average 38% larger than those of carnivorans, and that the rate of
larynx evolution is faster in these species.

There is also more variation in larynx size relative to body size among primates, indicating that primates have greater flexibility to evolve
in different ways. Carnivorans follow more of a fixed larynx-size to
body-size ratio.

Larynx size was also found to be a good predictor of the call frequency
of a species, which demonstrates the relevance for vocal communication
of the observed size variations.

Co-lead author Dr Jacob Dunn, Reader in Evolutionary Biology at Anglia
Ruskin University (ARU), said: "This study demonstrates clear differences
in the evolution of the larynx between groups of mammals.

"Specifically, we have shown for the first time that the primate
larynx is larger, less closely linked to body size, and under faster
rates of evolution than the carnivoran larynx, which is a well-matched comparison group, indicating fundamental differences in the evolution
of the vocal organ across species." Co-lead author Dr Daniel Bowling, Instructor in Psychiatry and Behavioral Sciences at Stanford University,
added: "Our study also shows that differences in larynx size predict
changes in voice pitch, highlighting the larynx's crucial role in vocal communication. This is demonstrated by the rich and varied calls produced
by many primate species.

"The results imply fundamental differences between primates and
carnivorans in the forces constraining larynx size, as well as
highlighting an evolutionary flexibility in primates that may help
explain why they have developed complex and diverse uses of the vocal
organ for communication. This provides an exciting avenue for future
studies examining variation among other mammalian groups."

========================================================================== Story Source: Materials provided by Anglia_Ruskin_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Daniel L. Bowling, Jacob C. Dunn, Jeroen B. Smaers, Maxime Garcia,
Asha
Sato, Georg Hantke, Stephan Handschuh, Sabine Dengg, Max Kerney,
Andrew C. Kitchener, Michaela Gumpenberger, W. Tecumseh Fitch. Rapid
evolution of the primate larynx? PLOS Biology, 2020; 18 (8):
e3000764 DOI: 10.1371/ journal.pbio.3000764 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200811142902.htm

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