Professor Ben Wheatley examines the interior structures of sheep horns.
Photo: Emily Paine
The Secrets of Sheep Skulls
Study explores how horns’ ability to withstand impact relates to other forceful encounters
by Matt Hughes
It’s one of the most violent spectacles in nature: Two bighorn sheep square off, rear up on their hind legs and rush, dropping down at the last moment to crash their horns together with maximum impact. And then they do it again, sometimes for hours on end, before walking away seemingly unaffected.

Bucknell Professor Benjamin Wheatley, mechanical engineering, witnessed these clashes while studying for his doctorate at Colorado State University in the Rockies. It sparked his curiosity. If such violent collisions cause concussions and even life-threatening injuries in humans, he wondered, how can sheep avoid such trauma?

Together with Jake Schaefer ’24 and collaborators at institutions that include Colorado State and UMass Amherst, Wheatley is now answering that question — and exploring applications for the secrets of sheep skulls to help protect everyone from athletes to car drivers and passengers. In November, the researchers published a paper in the journal Scientific Reports examining how the interior structure of horns might be mimicked to improve shock absorption in sneakers.

Their study examined the latticework of struts and gaps inside bone structures at the base of the horns. First, real skulls provided by Colorado’s Department of Natural Resources (from sheep killed in motor-vehicle accidents) were imaged using a CT scanner. The support structures were then digitally optimized and remade with 3D printers, providing models to test with real-world equipment.

While the team’s early findings were mixed (the structures weren’t as flexible as sneaker soles in absorbing sudden impacts, although they stored energy just as well), the researchers have also gathered promising data about how the vibration of horns may help dissipate force after impact.

That’s where Schaefer comes in. Using the computer-aided design program Fusion 360, the mechanical engineering major from Lancaster, Pa., is exploring how force mechanics vary when he tweaks the horns’ shape. He’s bringing that analysis into the real world this spring by using a drop tower to test impacts on different configurations of 3D-printed horns.

It’s the perfect project for Schaefer, who chose his engineering major to uncover how his innate fascination with math and physics plays out in the real world.

“Thousands of years of evolution led to these structures being this optimized,” he says. “These animals developed this stuff for a reason, and it’s really interesting to think about the possible applications we might develop from that.”