Why Do Some Dog Breeds Have Floppy Ears?
If you ever wondered why some dog breeds have floppy ears and others do not, consider that this is a very valid question. After all, if we look at other species of animals populating the world, we will readily notice a common trend: most wild animals have erect ears rather than floppy, pendulous ears.
To better understand why some dogs have floppy ears it therefore helps to take a closer insight into the process of domestication and selective breeding and how this has impacted dogs and their conformation.
A List of Dog Breeds With Floppy Ears
Before proceeding into understanding why some dog breeds have floppy ears, it helps to first identify what dogs breeds are known for having naturally floppy ears in the first place.
You will notice how several of the below dog breeds are scent hounds, dogs selectively bred for their powerful noses, and sporting dogs, dogs bred for their ability to hunt along with humans. Of course, this list is only partial, there are many more dog breeds with floppy ears.
- Basset hound
- Golden retriever
- Labrador retriever
- Flat-coated retriever
- Chesapeake Bay retriever
- Nova Scotia duck tolling retriever
- Cocker spaniel
- Saint Bernard
- Doberman pinscher
- Great Pyrenees
- Rhodesian ridgeback
- Bernese mountain dog
- Chinese shar-pei
A Look Back in History
Skeletal evidence from western Russia informs us that dog domestication dates back to at least 19,000 years. As the human and dog partnership flourished, dogs were utilized to carry out a vast array of highly specialized tasks.
Through selective breeding, the process of handpicking dogs with distinctive traits for the purpose of producing offspring with desired traits, humans began the process of shaping dogs that had the potential to help humans survive.
Depending on local needs and the needs of a specific era, some dogs were therefore selectively bred to herd goats in mountainous regions, while other dogs were selectively bred to hunt certain types of animals or guard properties and alert owners of their findings.
Hence, for sake of some examples, we have sighthounds who were selectively bred for their speed and superior vision to detect hare on vast open deserts, dachshunds who were selectively bred to have elongated bodies to reach down badgers in their tunnels, and rat terriers who were selectively bred for their speed and tenacity so to hunt vermin off 20th century American farms.
It is thanks to this tinkering with genetics and deliberate selection, that humans nowadays are gifted with such diversity of dogs coming in all shapes, sizes, colors and dog ear shapes.
A "Side Effect" of Domestication
Many dog owners wondering why some dogs breeds have floppy ears have likely observed how most wild animals have erect ears, rather than floppy pendulous ears. Jaguars, cheetahs, lions, zebras, deer, bears, racoons, and even wolves, who are known for being the ancestors of the dog, have erect ears. The only exception may be elephants.
On the other hand, there are several domesticated animals with floppy ears and these include goats, rabbits, pigs, donkeys, alpaca, llama and then you have several breeds of dogs and their mixes.
Interestingly, an experiment known as the "farm fox experiment" provides an interesting insight into the process of dog domestication. It all started when scientist Dmitry Belyaev started studying Vulpes Vulpes, the 'silver fox' in the late 1950s.
Dmitry started selecting the tamer foxes while discarding the most vicious ones, in a process that somewhat mimicked the domestication process of dogs. This breeding program continued for 26 years and still continues as of today.
As selection for the tamer foxes took place, some interesting morphological changes started happening. Perhaps the most relevant was a drastic coat change. The tamer foxes started losing their distinctive silver coat color in lieu of a piebald colored coat. Since they were no raised in captivity, apparently they no longer needed the silver coat to camouflage in the wild!
On top of this, the foxes developed shorter legs, floppy ears and curled tails, which are traits seen in many domesticated dogs today.
The floppy ears, in particular, were classified as an effect of pedomorphosis. Also, known as "neoteny," pedomorphosis is the technical term to depict a tendency to retain juvenile traits through adulthood. Charles Darwin has an interesting theory for the onset of floppy ears in the quote below.
"Not a single domestic animal can be named which has not in some country drooping ears; and the view suggested by some authors, that the drooping is due to the disuse of the muscles of the ear, from the animals not being much alarmed by danger, seems probable." ~Charles Darwin, On the Origin of Species by Means of Natural Selection
The Effect on a Dog's Ear Cartilage
Domestication syndrome is a term used to depict the presentation of traits occurring as a result of domestication which distinguish domesticated animals from their wild ancestors. How does domestication though directly impact the ears?
A primary role must be played by the adrenal glands. The adrenal gland are special glands known for producing a variety of hormones including adrenaline and the steroids aldosterone and cortisol. These substances are known for being released during the fight or flight response, which is likely to occur with greater intensity and frequency in wild animals.
Somewhere along the process of domestication, as humans selectively bred for the tamest specimens, a dog's fight and flight responses must have reduced, causing the adrenal glands to at some point become smaller.
"Since adrenaline production normally increases in the transition into adulthood, many of the low-adrenaline animals also retained floppy ears and pushed-in snouts, both indicators of domestication," explain Richard Bulliet et al. in the book "The Earth and its peoples: a global history." It almost seems as, through the process of domestication, dogs are somewhat stuck in a perpetual juvenile state.
Now, how do adrenal glands relate to ear cartilage formation? It appears that special stem cells involved in the formation of the adrenal glands known as called "neural crest cells" play a big role.
According to research by Adam S. Wilkins, these cells are known for migrating to various parts of the body and they play a role in the formation of body parts associated with domestication such as some bony, cartilaginous components of the craniofacial region, including the jaws, hyoid, larynx, and external and middle ears.
So how are those ears once again impacted by all of this? Richard Wrangham author of the book "The Goodness Paradox: The Strange Relationship Between Virtue and Violence" has a good explanation, he claims in the quote below:
"Ears are floppy if the internal cartilage is too short, leaving the end part of the ear unsupported and liable to flop over. So animals with floppy ears appear to be those whose cartilage received relatively minor amounts of neural crest cells."
A Need for Floppy Ears
If therefore comes natural asking next: on top of domestication, is it possible that humans may have purposely bred some dog breeds to have floppy ears? It is possible.
While the floppy ear most definitely may have occurred as a "side effect" of the domestication process as observed in the farm fox experiment, in some dog breeds, it's likely the result of selective breeding for certain traits.
For instance, as mentioned, many dogs with floppy ears are scent hounds (such as beagles, basset hounds and bloodhounds). In these breeds, which have an exaggerated form of floppy ears, with their ears often touching the ground, those long, pendulous ears have an important function.
When tracking, with their noses low to the ground, those ears drag to the ground stirring up scent molecules, observes Anne Legge, a breeder of champion bloodhounds in the book "Dogspeak: How to Understand Your Dog and Help Him Understand You."
And what about other dog breeds? Many of the dog breeds in the sporting group with floppy ears such as Labrador retrievers, Golden retrievers, flat-coated retrievers, Chesapeake Bay retrievers and Nova Scotia duck tolling retrievers may have been selectively bred with floppy ears for the simple fact that these dogs were often swimming to retrieve downed birds. Those floppy ears may have protected the ears from getting water in them.
And then you have several small breeds with floppy ears such as pugs, which may have been selectively bred for this trait just due to the "cutesy factor. "