Floppiness of Ears Varies in Dog Breeds
The famous floppy ears seen on many dog breeds is one of the defining characteristics that sets dogs apart from their wild wolf ancestors. Yet not all dogs have floppy ears. Ear shape varies significantly across different breeds, from fully erect ears like the German Shepherd to long, drooping ears like the Basset Hound.
This raises an interesting question – why do some dogs develop floppy ears while others retain the pointed ears of wolves? The answers lie in the history of domestication and the power of artificial selection in shaping the traits of our canine companions.
Floppy Ears in the Wild
In the wild, canines like wolves typically have erect, upright ears. This gives them an evolutionary advantage as they rely heavily on their sense of hearing to hunt prey and be alert to potential dangers. According to one source, “Wolves, the ancestors of domestic dogs, have erect ears. In fact, in the wild, most canine species have upright ears” (source).
Erect ears can swivel and turn to precisely pinpoint the source of a sound. This allows wild canines to effectively track prey or respond to approaching predators. Floppy ears would be a disadvantage for survival, as they can muffle sounds and make it harder to locate the direction a sound is coming from. Having upright ears was evolutionarily advantageous for wild canines like wolves to excel at hunting and staying safe in their natural habitat.
Domestication Changed Ear Shape
The process of domestication led to floppy ears in dogs. As wolves were tamed over thousands of years, becoming the dogs we know today, major changes happened to their physical appearance. One of the most noticeable changes was ears that went from pointed and erect to soft and floppy.
Researchers believe this change in ear shape is related to a condition called domestication syndrome. As animals like wolves were selectively bred for domestication, a whole host of traits changed, including floppy ears. It’s believed that the same genes that control things like coat color, curly tails, and sociability also affect ear cartilage strength. Over time, as these other traits were selected for, floppy ears emerged as well. The soft ears seen in many dog breeds did not appear by chance but were a byproduct of domestication.
There are a few theories on why this happened. As dogs became domesticated, they no longer needed erect ears for activities like hunting. Their softer ears also made dogs appear less threatening to humans. Additionally, floppy ears may have developed because of changes in hormone levels or reductions in tissue density in the ear cartilage. Whatever the reason, floppy ears have become a hallmark of domestic dogs.
Artificial Selection
Humans began intentionally breeding dogs for certain desired traits, a process known as artificial selection. One of the traits that was selected for was floppy ears. According to research from Princeton University, floppy ears emerged as a byproduct of selection for tameness during early domestication (source).
In a famous experiment starting in the 1950s, Russian geneticist Dmitry Belyaev bred foxes to be tamer by selecting for the least fearful and aggressive foxes to breed each generation. Over time, the foxes developed floppy ears and curly tails along with increased tameness (source). This demonstrated that selecting for behavioral traits can also produce physical changes.
Similarly, early dog domestication involved selecting the tamest wolves to breed. The physical trait of floppy ears emerged as a byproduct of selecting for tameness. Humans then intentionally bred dogs to enhance this trait, as floppy ears were considered cute and desirable.
Less Need for Erect Ears
Domestic dogs don’t rely on erect ears in the same way as their wild wolf ancestors. Wild canines like wolves and coyotes use their upright ears to help locate and pinpoint sounds while hunting prey across long distances. Their tall, erect ears can rotate nearly 180 degrees to detect the faintest noises. This acute sense of hearing helps wild canines survive in nature.
In contrast, domesticated dogs no longer need such sensitive erect ears. As human companions, housedogs are less reliant on their hearing while living indoors and being provided food by their owners. With less need to locate prey, their ears gradually became more floppy over time. According to one study, “the reduced functionality required in ears of domesticated species relaxed selection on maintaining the wild-type phenotype.” https://bigthink.com/life/mystery-behind-dogs-domestication-syndrome/
So while wolves and coyotes retained their highly functional upright ears, domesticated dogs evolved more floppy ears as that strong hearing ability was no longer essential for survival.
Genetic Connection
Research has identified specific genes connected to floppy ears in dogs. A 2015 study published in PLOS Genetics found that variations in the MsrB3 gene on canine chromosome 10 were strongly associated with ear carriage in different dog breeds (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4477608/). Breeds with erect ears like German Shepherds, Corgis, and Australian Cattle Dogs had one version of the gene, while floppy-eared breeds like Beagles, Basset Hounds, and Cocker Spaniels had a different version.
This indicates that differences in the MsrB3 gene play a major role in determining ear cartilage strength and ear floppiness. However, other genes also influence ear carriage to a lesser degree. Overall, the genetics of ear shape in dogs is complex with several genes interacting, but the chromosome 10 connection remains the most significant finding.
Floppy Puppy Ears
All puppies are born with floppy ears initially, regardless of breed. A puppy’s ears are folded over and quite soft when they are first born. The cartilage in the ear has not yet developed enough to hold the ear upright. Puppies’ ears usually start standing up when they are between 3-5 weeks old, though some breeds take longer for their ears to stand up straight.
According to Hound Games, German Shepherds’ ears typically stand up between 4-7 months old, once the cartilage fully hardens. For some larger breeds like Great Danes, it can take up to a year for their heavy, floppy ears to stand upright as the cartilage develops and strengthens. But all puppies, even breeds with perky, pointy ears, are born with folded down, floppy ears that are soft to the touch.
Exceptions to the Rule
While most domesticated dog breeds have floppy ears, there are some exceptions. Certain breeds like the Siberian Husky, Alaskan Malamute, German Shepherd, Belgian Malinois, and Australian Cattle Dog have continued to be bred to retain upright, pointy ears despite domestication. According to Pawtypooch, these breeds were often bred to herd livestock, pull sleds, or assist in hunting. Their erect ears likely helped improve hearing and were seen as a desirable trait to preserve. For example, the Siberian Husky was bred by the Chukchi people in eastern Siberia to pull sleds over long distances. Maintaining excellent hearing would have been advantageous for working with people and responding to commands. So despite domestication, deliberate selective breeding in certain working dog breeds has maintained erect ears as a breed standard.
Theories on Function
There are several theories about why domestic dogs evolved to have floppy ears compared to their wild wolf ancestors:
One idea is that floppy ears helped dogs better communicate with humans through body language. The floppier ears enabled dogs to make more varied ear movements that humans could intuitively understand. This facilitated bonding between humans and dogs.
Another theory is that floppy ears reduced aggression between dogs. Erect ears are often used for threatening signals in the wild. Floppy ears may have made domestic dogs appear less threatening and reduced fighting amongst themselves. This enabled dogs to live peacefully together and interact with humans.
Some experts think floppy ears helped dogs hear wider ranges of frequencies, allowing them to better understand human speech and commands. The different ear shape may have enabled domestication by improving comprehension of verbal cues.
There are also ideas that floppy ears improved heat dissipation for dogs living indoors. The larger flap of hanging ear skin helped radiate excess body heat. This allowed dogs to adapt to the warmer environments of human habitation.
While the exact reasons are still debated, most experts agree floppy ears served an adaptive purpose early in dog domestication. The trait proliferated because it gave dogs an advantage when living and working closely with people.
Conclusion
Based on the information discussed, we can conclude that while it is not universal, most domesticated dog breeds do indeed have floppy ears compared to their wild wolf ancestors. Domestication led to artificial selection for floppy ears in dogs. While the evolutionary reasons are still debated, some theories point to less need for erect ears for hunting or intimidation of rivals. There are also interesting anatomical facts like dogs having 18 muscles in each ear compared to humans having just 6. Whatever the reasons, floppy ears have become the dominant trait in domesticated dogs, though some breeds like huskies and German shepherds still have mostly upright ears.
In summary, key points we covered were:
- Wolves and wild canines have upright, erect ears
- Floppy ears emerged as dogs were domesticated by humans
- Artificial selection led to genetic changes favoring floppy ears
- Theories point to less need to show aggression or hunt
- Dogs have more ear muscles than humans – 18 vs 6 per ear
- Most but not all domesticated dogs have floppy ears now
While the reasons are still not fully settled, clearly domestication changed dog ear shape over time, making floppy ears the norm for our canine companions today.
