The study is the largest ever investigation into laryngeal evolution across species.
Scientists have found that the larynx, or sound box, of primates is significantly larger compared to body size, has greater variation, and is below faster rates of evolution than other mammals.
Published in the magazine Biology PLOS and led by academics from Anglia Ruskin University (ARU), Stanford University and the University of Vienna, the research is the first large-scale study on laryngeal evolution.
The larynx has three main functions: protecting the airway during feeding, regulating the air supply to the lungs, and vocal communication. Due to its important role in facilitating social behavior through vocalization, it has long been believed that the larynx is a key area of evolution, especially in species with highly developed vocal communication systems.
The researchers scanned samples from 55 different species, and produced 3D computer models of their larynxes. These were studied in addition to detailed measurements, including body length and body mass.
Primates ranged in size from a pygmy marmoset (Cebuella pygmaea) weighing only 110 g, to a western gorilla (Gorilla Gorilla) weighing approximately 120 kg. Carnivores ranged from a common 280g dwarf mongoose (Helvale parvula) to a 180kg tiger (Panthera tigris).
The study found that, for a given body length, primary larynxes are on average 38% larger than those of carnivores, and that the rate of laryngeal evolution is faster in these species.
There is even more variation in laryngeal size compared to body size among primates, indicating that primates have a greater flexibility to develop in different ways. Carnivores follow more of a fixed ratio of laryngeal size to body.
The size of the larynx was also found to be a good predictor of the calling frequency of a species, which indicates the importance for the vocal communication of the observed size variations.
Co-author, Dr. Jacob Dunn, Reader in Evolutionary Biology at Anglia Ruskin University (ARU), said: “This study demonstrates clear differences in laryngeal evolution between groups of mammals.
In particular, we have shown for the first time that the primate larynx is larger, less related to body size, and at faster rates of evolution than the carnivorous larynx, which is a matching comparison group. , which shows fundamental changes in the evolution. of the vocal organ across species. “
Co-author Dr. Daniel Bowling, Instructor in Psychiatry and Behavioral Sciences at Stanford University, added: “Our study also shows that changes in laryngeal size predict changes in voice, emphasizing the key role of the larynx in vocal communication. This has been demonstrated by rich calls and diverse produced by many primitive species.
“The results imply substantial differences between primates and carnivores in the forces that limit the size of the larynx, as well as highlight 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 a interesting pathways for future studies examining differences between other groups of mammals. “