Uploaded April 2013 | Updated September 2026, 3 hours ago

---

**ORDER our new book: WeHaveNoIdea.com

Even though they evolved 40 million years and thousands of miles apart, dogs and hyenas converged on the same design for their bone-crushing jaws - how cool is that?! Dr. Zhijie Jack Tseng explains his thesis in two minutes!

More videos at PHDtv: phdcomics.com/tv
Can't watch now? Read about it at phdcomics.com/tv/#035

Subscribe to our channel: youtube.com/subscription_center?add_user=phdcomics

More info: sites.google.com/site/zjtseng

Credits:
Animation by: Jorge Cham and Meg Rosenburg
Series Producer: Meg Rosenburg
Zhijie Jack Tseng, Ph.D., U. of Southern California & the Natural History Museum of L.A. County