When it comes to bears, people often wonder whether they are more closely related to dogs or cats. At first glance, bears seem very different from domestic dogs and cats. However, there are some important biological similarities between bears and these familiar carnivorans that provide clues about their evolutionary relationships.
In this article, we’ll take an in-depth look at the anatomy, behavior, and genetics of bears, dogs, and cats. We’ll examine the evidence to determine where bears fall on the carnivoran family tree. Are they more dog-like or cat-like? Or do bears represent a lineage that split off long before the emergence of modern canines and felines? By the end, you’ll have a better understanding of how bears compare to their carnivoran cousins.
The Carnivora Order
Dogs, cats, and bears all belong to the biological order Carnivora. This group consists of over 280 species of mammals that are primarily meat eaters. Some of the most well-known carnivorans include wolves, big cats, hyenas, raccoons, seals, and weasels.
The Carnivora order split off from other mammal groups over 42 million years ago, during the Eocene Epoch. Based on anatomical features, carnivorans are classified into two main subgroups:
Feliformia (“cat-like” carnivorans)
– Examples: cats, hyenas, mongooses, civets
Caniformia (“dog-like” carnivorans)
– Examples: dogs, bears, raccoons, mustelids (weasels, otters, etc.)
So how do bears fit into this framework? Let’s look at some of the key similarities and differences between bears and their caniform and feliform relatives.
Anatomy and Physiology
When it comes to their general body plan, bears share some notable features with both dogs and cats. Let’s start with a rundown of bear anatomy:
- Bears have a typical carnivoran body shape, with stocky torso, short limbs, and long snout.
- Their paw structure is plantigrade (heel and sole touching the ground) like canines, rather than digitigrade (walking on toes) like felines.
- Bears have non-retractable claws like dogs, but the claws are curved like those of cats.
- They have excellent senses of smell and hearing like dogs and cats.
- Bears are omnivores, with a diet ranging from vegetation to meat. This is similar to some canids like foxes.
- Their teeth reflect their omnivorous diet, with large canines for capturing prey as well as grinding molars for plant material.
- Bears have carnassial teeth that allow them to shear meat, a trait shared with all carnivorans.
- They have a simple stomach unlike ruminants, but a shorter intestine than many carnivores since they eat more plant material.
- Bears are digitigrade, walking on the toes with heels elevated like felines and unlike canines.
Overall, the physiological evidence suggests bears are carnivorans adapted for a generalized, omnivorous diet. Their digestive system, teeth, and feet indicate a mix of features found in dogs, cats, and their other carnivoran cousins.
Behavior
In terms of their behavior patterns, bears again show a combination of dog-like and cat-like traits:
Dog-like behaviors
- Bears have excellent senses of smell that they rely on for finding food, tracking prey, and even communicating with other bears.
- They are generally social animals, especially brown and black bears. They do not maintain highly complex social structures like wolves, but do interact outside of mating.
- Bears sometimes rear up on hind legs to communicate, similar to how some dogs stand on hind legs.
- Cubs stay with mothers for extended periods, even hibernating beside them, reminiscent of pack bonding in wolves.
- Bears are intelligent and can be trained, though not to the advanced level of some domestic dog breeds.
Cat-like behaviors
- Bears are primarily solitary animals outside mating season, coming together only briefly to feed or mate.
- Mothers rear cubs on their own and teach them survival skills before the cubs disperse.
- They are ambush predators that quietly stalk prey using stealth and camouflage.
- Bears are agile tree climbers, aided by curved claws, similar to leopards.
- They are territorial and use scratch marks, urine, and feces to mark boundaries.
The evidence indicates bears have a flexible behavioral repertoire that includes traits found in both canine and feline species. Their adaptability likely helps bears thrive in diverse habitats.
Genetics
Modern genomic research allows us to directly compare the DNA sequences of different species. Numerous studies have constructed carnivoran family trees using genetic data. Almost uniformly, these studies confirm bears are true caniforms, closely related to dogs, raccoons, and weasels.
Some key genetic findings on bear ancestry:
- Bears split from other caniform lineages about 38 million years ago.
- Giant pandas diverged from other bears about 22 million years ago.
- Brown bears and polar bears diverged 500,000-5 million years ago.
- All bears are more closely related to one another than to any feliform taxa.
- Genes place bears firmly within the caniform clade, not the feliform clade.
The molecular evidence decisively shows that bears arose from within the caniform lineage of carnivorans long after that group separated from the feliformes. They are not intermediate between dogs and cats. Based on their genetics, bears are evolutionary caniforms.
Conclusion
After this deep dive into bear anatomy, behavior, and genetic, how do bears compare to dogs and cats? The evidence points to bears being fundamentally caniform carnivorans that split from a common ancestor with dogs and other caniform taxa around 40 million years ago. They are more closely related to dogs than cats. However, during their evolution, bears developed physical and behavioral traits that appear cat-like, likely adaptations for their predatory lifestyle. So while bears are certainly more dog-like, they display an interesting mix of traits found in both major groups of carnivorans. Hopefully this overview gave you a better appreciation for how bears fit into the carnivoran family tree!
References
Flynn, J. J., Finarelli, J. A., Zehr, S., Hsu, J., Nedbal, M. A. (2005). Molecular phylogeny of the Carnivora (Mammalia): assessing the impact of increased sampling on resolving enigmatic relationships. Systematic Biology, 54(2), 317-337.
Krause, J., Unger, T., Noçon, A., Malaspinas, A. S., Kolokotronis, S. O., Stiller, M., … & Hofreiter, M. (2008). Mitochondrial genomes reveal an explosive radiation of extinct and extant bears near the Miocene-Pliocene boundary. BMC evolutionary biology, 8(1), 1-12.
Slater, G. J., Figueirido, B., Louis, L., Yang, P., & Van Valkenburgh, B. (2010). Biomechanical consequences of rapid evolution in the polar bear lineage. PloS one, 5(11), e13870.
Sato, J. J., Wolsan, M., Minami, S., Hosoda, T., Sinaga, M. H., Hiyama, K., … & Hongo, H. (2009). Deciphering and dating the red panda’s ancestry and early adaptive radiation of Musteloidea. Molecular phylogenetics and evolution, 53(3), 907-922.
Law, C. J., Slater, G. J., & Mehta, R. S. (2018). Lineage Diversity and Size Disparity in Musteloidea: Testing Patterns of Adaptive Radiation Using Molecular and Fossil-Based Methods. Systematic biology, 67(1), 127-144.
Summary Table Comparing Bears, Dogs, and Cats
| Trait | Bears | Dogs | Cats |
|---|---|---|---|
| Claws | Non-retractable but curved | Non-retractable | Retractable |
| Diet | Omnivorous | Omnivorous (varies by breed) | Obligate carnivores |
| Teeth | Carnassials for shearing, plus grinding molars | Carnassials for shearing | Carnassials for shearing |
| Social Structure | Generally solitary but some social interaction | Highly social and cooperative | Solitary except brief mating interactions |
| Locomotion | Plantigrade (heel touches ground) like canines | Plantigrade | Digitigrade (walks on toes) |
| Phylogeny | Within caniform clade | Within caniform clade | Within feliform clade |