Scientists Discover Key Factor In How Whales Evolved From Land To Sea Mammals

whale ear bones

When it comes to hearing underwater, most mammals’ ears just aren’t up to the task.

For humans, it’s partly because the density of our eardrums is too close to the density of water, the Dartmouth Undergraduate Journal of Science reports. Then there’s the fact that sound waves travel four to five times faster underwater, so our eardrums have a hard time picking up the disturbances.

But while whales were land mammals 50 million years ago, they have evolved to hear each other incredibly well underwater — up to 1,000 miles apart, according to National Geographic. New research from the Smithsonian National Museum of Natural History finally shows how.

The discovery came when Maya Yamato, a postdoctoral fellow in the Smithsonian’s Department of Vertebrate Zoology, analyzed 56 fetus specimens of toothed and baleen whales from the museum’s collection by sending them through a CT scanner. Smithsonian Magazine heralds the nondestructive approach as a possible game-changer for future studies since the specimens, which were mostly collected from commercial whaling operations in the early to mid-20th century, are too fragile and rare to examine via traditional research methods.

Why fetuses?

“How we grow, especially in utero, tells us a lot about how we have evolved,” collection curator Nicholas Pyenson, who participated in the study, told the magazine. “So looking at fetal data can give us a lot of answers in terms of how an animal develops.”

In this 3D reconstruction of a fin whale fetal skull, the yellow markings represent the early developmental stages of ear bones.

Yamoto and Pyenson found “early fetuses have features in their ears that can be recognized as components of a typical mammalian ear,” even land mammals, she told The Huffington Post.

But as the fetus grows inside the womb, Yamoto and Pyenson —> Read More