Those droopy ears that make a Basset Hound so lovable? They come from a surprisingly complex genetic puzzle that researchers at the University of Georgia have started to solve. And the answer might explain more than just why some dogs look sadder than others.
Leigh Anne Clark wasn’t hunting for ear genes when undergraduate Anna Ramey showed up at her lab. Clark studies canine diseases, the kind of work that maps genetic mutations to help breeders avoid passing on hereditary problems. But Ramey had a Cocker Spaniel with especially magnificent ears. She wondered: Could genome sequencing reveal what makes some dog ears dangle while others stand straight up?
That question led Clark’s team to analyze DNA from over 3,000 dogs, wolves, and coyotes. What they found surprised them. There’s not just one gene controlling ear length. Instead, three separate genetic variants cluster together on chromosome 10. Each one contributes on its own to how ears develop and whether they fold over or stand upright like a Husky’s.
The main variant sits in a region that’s stayed the same across many species. In humans, this region loops through three-dimensional space to interact with an enhancer for MSRB3 (a gene that influences ear size in pigs, sheep, and goats).
Here’s where it gets really interesting. The same chromosomal region that determines ear length also controls ear carriage, whether ears stand up or flop down. Earlier studies had found this spot, but researchers thought it was simple: one variant for floppy, another for upright.
Clark’s analysis revealed something more complex. Two independent mutations popped up on different ancestral versions of the chromosome. Neither one alone produces drop ears. Only when both variants show up together do ears reliably fold over. Then a third mutation appeared specifically on this combined background. This three-part combination (found in breeds like Bloodhounds and Basset Hounds) produces the longest drop ears in dogs.
The original version, still present in wolves and coyotes, goes with small, upright ears. Breeds that kept this ancient genetic signature (Siberian Huskies, Norwegian Elkhounds) typically have compact, upright ears good for conserving heat in cold climates. Meanwhile, breeds from warmer regions often carry the newer variants.
This makes sense from an evolutionary standpoint. Across species, external ear size varies wildly because ears are crucial for temperature regulation. Large ears shed heat. Small ones keep it in. Jackrabbits have huge, blood-vessel-rich ears for cooling in the desert. Arctic hares have compact ones to minimize heat loss. Farm animals from hot climates (Brahman cattle, Awassi sheep) show similar patterns.
Dogs are unique because breeding pressures for ear shape aren’t always about function. Breeders often pick for looks over temperature control. Still, the general pattern holds. Desert breeds like Pharaoh Hounds and Rhodesian Ridgebacks usually have larger ears.
Clark’s findings suggest that each new variant may independently increase ear size. That in turn affects whether ears stand or droop. Bigger ears are simply more likely to fold under their own weight. The team found strong evidence of selection at this genetic spot in long-eared breeds compared to prick-eared ones. But the signal was much weaker in short drop-eared breeds, which fits with greater genetic variety.
One catch: The study used breed standard ear lengths rather than measurements from individual dogs. Future work using actual measurements from breeds with variation in both ear length and genetic makeup could reveal more about how these variants work together.
https://www.nature.com/articles/s41598-025-33036-0
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