Audiograms of howling monkeys: are extreme loud calls the result of runaway selection?
Abstract
Abstract The eponymous vocalizations of howling monkeys (genus Alouatta ) are associated
with territorial defense and male-male competition, yet the extreme loudness of howls,
which are among the loudest vocalizations of any terrestrial mammal, have yet to be
fully explained. Loudness facilitates long-distance sound propagation but the effectiveness
of any vocal signal depends in part on the auditory capabilities of the intended receiver,
and the auditory sensitivities of howling monkeys are unknown. To better understand
the evolution of loud calls, we used the auditory brainstem response (ABR) method
to estimate the auditory sensitivities of Alouatta palliata . The mean estimated audiogram
of four wild-caught adults displayed a w-shaped pattern with two regions of enhanced
sensitivity centered at 0.7-1.0 and 11.3 kHz. The lower-frequency region of auditory
sensitivity is pitched moderately higher than the fundamental frequencies of howling,
whereas the higher-frequency region corresponds well with harmonics in an infant distress
call, the wrah-ha . Fitness advantages from detecting infants amid low-frequency background
noise, including howling, could explain the incongruity between our ABR thresholds
and the fundamental frequencies of howling. Attending to infant calls is expected
to enhance reproductive success within an infanticidal genus, and we suggest that
the extraordinary loudness of male howling is an indirect (runaway) result of positive
feedback between the selective pressures of hearing infant distress calls and deterring
infanticide.
Type
Journal articlePermalink
https://hdl.handle.net/10161/21100Published Version (Please cite this version)
10.1101/539023Publication Info
Ramsier, Marissa; Cunningham, Andrew; Patiño, May; Glander, Kenneth; & Dominy, Nathaniel (2019). Audiograms of howling monkeys: are extreme loud calls the result of runaway selection?.
10.1101/539023. Retrieved from https://hdl.handle.net/10161/21100.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
Collections
More Info
Show full item recordScholars@Duke
Kenneth Earl Glander
Professor Emeritus of Evolutionary Anthropology
Primate ecology and social organization: the interaction between feeding patterns
and social structure; evolutionary development of optimal group size and composition;
factors affecting short and long-term demographic changes in stable groups; primate
use of regenerating forests.

Articles written by Duke faculty are made available through the campus open access policy. For more information see: Duke Open Access Policy
Rights for Collection: Scholarly Articles
Works are deposited here by their authors, and represent their research and opinions, not that of Duke University. Some materials and descriptions may include offensive content. More info