EMBARGO: March 11, 2015 11 AM Pacific / 2 PM Eastern
Scientists reconstruct evolutionary history of whale hearing
Decades-old museum specimens reveal window into whale
hearing
Changes in ear bone development in the womb paralleled
changes observed throughout whale evolution, providing
new insight about how whales adapted to hearing
underwater, according to a study published March 11, 2015
in the open-access journal PLOS ONE by Maya Yamato and
Nicholas Pyenson from Smithsonian Institution National
Museum of Natural History.
Whales receive underwater sounds through a different
mechanism than their close terrestrial relatives. Instead of
hearing through the ear canal, cetaceans hear through
specialized fatty tissues leading to an evolutionarily novel
feature: an acoustic funnel located anterior to the tympanic
aperture. The acoustic funnel is thought to be a critical
component to understanding how baleen and toothed
whales hear underwater. Using non-invasive X-ray
computed tomography (CT) imaging techniques, the
authors of this study traced the development of fetal ear
bones in 56 specimens from 10 different families of toothed and baleen whales. They observed how ears develop in
unborn whales of modern species, and compared these changes with those reflected in the fossilized ears of extinct whales
over the course of millions of years.
Their findings confirmed that changes in the development of ear bones in the womb paralleled changes observed
throughout whale evolution, providing new insight about how whales shifted from land to sea and adapted to hearing
underwater.
“Whale ears are incredibly complex organs. Although scientists know that hearing is one of the most important senses that
whales use to communicate, navigate and search for food in their underwater world, we are still searching for clues about
how their ears actually work,” said Maya Yamato. “This research provides a window into evolutionary processes that took
place millions of years ago, and helps explain how whales evolved to hear after they moved from living on land to thriving
in today’s oceans.”
Whales rely on sound to communicate with each other, forage, and navigate through water.
Understanding how whales hear is essential to protecting populations in the future as ocean noise from human activities,
including global shipping, seismic surveys, and sonar training, continues to rise.
Adapted by PLOS ONE from release provided by the author
In your coverage please use this URL to provide access to the freely available paper:
http://dx.plos.org/10.1371/journal.pone.0118582
Press-only preview: http://www.plos.org/wp-content/uploads/2013/05/pone-10-3-Yamato.pdf
Contact: Ryan Lavery, Laveryr@si.edu; Katie Sabella, Sabellak@si.edu. Both also available at (202) 633-2950
Image Credit: Yamato et al.
Citation: Yamato M, Pyenson ND (2015) Early Development and Orientation of the Acoustic Funnel Provides Insight into
the Evolution of Sound Reception Pathways in Cetaceans. PLoS ONE 10(3): e0118582. doi:10.1371/journal.pone.0118582
Funding: Support for this work came from a NMNH Peter Buck Postdoctoral Fellowship to MY, and the NMNH Remington
Kellogg Fund to NDP (http://www. mnh.si.edu/). The funders had no role in study design, data collection and analysis,
decision to publish, or preparation of the manuscript.
Competing Interests: NDP is an academic editor for PLOS ONE. This does not alter the authors’ adherence to PLOS ONE
policies on sharing data and materials.