Since the Stone Age, people have claimed to be cat or dog lovers, according to new research, but our pets are actually more closely related than you might think.
The question of whether you prefer dogs or cats is frequently presented as binary: if you value the steadfastness of a loyal dog, you can’t also savor the coquettish company of a kitty. According to recent studies, pet preferences may have been a source of division among humans since the Stone Age. But in terms of evolution, the situation is far from clear-cut. Dogs and cats should coexist because they share an ancestor. They are related to both large and small animals in a wide range of species. You could also inquire about your preference for meerkats, weasels, badgers, or hyaenas.
Our beloved pets belong to the order Carnivora. Along with marine members like seals, walruses, and sea-lions, this group also includes bears, hyaenas, mongooses, civets, skunks, and other animals. The name of the group is a little deceptive because not all mammals that consume meat belong to the Carnivora order, and not all Carnivora consume animal flesh.
Carnivorans (animals in the order Carnivora) have a number of characteristics in common, but their teeth are by far the most important. Their first lower molar and fourth upper premolar, which resemble blades, work in tandem to shear through food in all of them. Since many carnivorans live a predatory lifestyle, this design is particularly effective for snipping flesh. Others, like bears, which consume a wide variety of foods, as well as bintourongs and red pandas, which thrive on a diet primarily composed of plants, are more omnivorous. The so-called giant “panda”* has gone above and beyond by adopting a strict vegetarian diet that focuses exclusively on bamboo, though it has been known to eat the occasional fish, egg, or insect.
The ancestors of Carnivora are from a group of animals called miacids, which were once widespread across Eurasia and North America. So what ancestral family photograph do all of these seemingly disparate animals have mounted on the wall at home? They were small, long-bodied creatures that were at home in trees and somewhat resembled pine martens. Although it’s unclear exactly how these miacids are related, we do know that they persisted for more than 25 million years and only appeared a few million years after the dinosaurs went extinct. From among their slinky ranks, the earliest identifiable carnivorans emerged.
When it comes to killing, carnivora have not always been the top predators. After the asteroid wiped out the largest reptiles from the planet, two other dominant mammal groups emerged with specialized shearing teeth to prey on animals during those heady days of mammal divergence.
The largest land mammal predators ever were among the creodontans. They did not have premolars and molars like carnivorans did; only molars made up their carnassial teeth. This suggests that they evolved a niche for hunting and eating flesh apart from carnivorous animals, and they did so throughout Eurasia, Africa, and North America. Dissopsalis, the last known creodontan, perished only 8 million years ago, by which time carnivorans had supplanted them as the dominant predators of the animal kingdom.
Creodontans were not the only ones prowling the Palaeogene. The mesonychids are an even stranger race of meat-eaters from Asia who have colonized the northern hemisphere. They had special shearing and crushing molars to process meat instead of any carnassial teeth at all. Early species walked on flat feet, but later species, some of which had hooves on each toe, walked on their toes like cats and dogs. Scientists hypothesized that mesonychids were the ancestors of whales and dolphins because they shared many tooth and cranial characteristics with these marine mammals. They are sister groups, according to more recent research, and they all descended from the same ancestor as hippos.
The top predators at the time were mesonychids and creodontans, but both were eventually supplanted by carnivora, one of the most successful animal orders on earth. Uncertainty surrounds the precise reason why carnivorans outperformed their cousins, but it has been proposed that a variety of special adaptations, such as larger brains, more effective locomotion, and more versatile teeth, gave them the ecological advantage and enabled them to displace their rivals.
The debate between dogs and cats has some merit. The Carnivora are divided into two quite distinct groups: the caniformia, which are generally dog-like, and the feliformia, which are generally cat-like, despite having a common ancestor. This division has deep roots, around 43 million years.
The feliforms typically have shorter faces, retractable claws, and are more specialized meat eaters. Instead of being runners, many of them are ambush and pounce predators (the cheetah being a notable exception). In addition to the larger true cats and hyaenas, they also include the carnivorans of Madagascar, such as the fossa, meerkats, mongooses, civets, and genets (although some research suggests these may have split off from other carnivorans before the main feliformia/caniformia break up). Even a layperson can tell that the majority of these animals have a kitty-like disposition. Now you know, it’s more than skin deep.
The caniformia includes dogs, wolves, and jackals, all of which diverged from their canine-like ancestors early on. There are bears there, another early split from the rest of the group, giving the rest of Caniformia a startlingly diverse profile. With their short flippered limbs and rolls of fat, marine carnivorans have really gone to town when it comes to physical specialization. But the old slang term for seals, “sea-dogs,” suggests that humankind could see a family resemblance even before the science of anatomy confirmed it. Skunks, weasels, badgers, otters, racoons, and coatis are also members of this canine-friendly branch of the Carnivora, though their inclusion may be less obvious.
Recent studies have been investigating the origins of our domesticated friends from their wild ancestors, so what about the obedient hound and modest puss? Due to the discovery that dogs and modern grey wolves had a common ancestor, dogs have attracted a lot of attention. Although there is still some debate, it is believed that wolves were first domesticated (or domesticated twice; it may have happened in Eurasia and/or Europe). It may have happened accidentally or as a result of human design. Additionally, the timing has raised questions; according to a recent study published in Nature Communications, it might have happened as recently as 41,000 years ago.
Even more recently, it has been proposed in a different paper published this month that the earliest domesticated wolves had a canine form of the developmental disorder William’s syndrome. This is brought on by chromosome variations that, in humans, result in a high degree of sociability and what are referred to as “pixie-like” facial features. The idea is that because of their inherent desire to be man’s best friend, wolves with such a disorder may have easily interacted with humans. This possibility requires further study, but one thing is certain: since then, we have been breeding dogs for friendliness.
Cats haven’t been studied as thoroughly, but it’s been clear for a while that they were domesticated later and less vigorously than dogs. An international team recently conducted DNA analyses on cats from Europe, Asia, and Africa, including modern cat samples and ancient DNA from archaeological specimens, under the direction of scientists at KU-Leuven University in Belgium. Their research indicates that crazy cat ladies have existed since the Neolithic period, with waves of cat adoration beginning in the Near East and traveling the world via trade routes during the Egyptian dynasties. We didn’t start breeding for more frivolous characteristics like coat colors until after the Middle Ages, but we have long recognized the value of a committed mouser.
I’ll leave it up to you to consider your allegiances and pose your own who-would-win-in-a-fight-between questions. So, shall we pit the whole of dog-like Carnivora against the cat-like ones? Perhaps your preference for pooches extends to their cousins, and you find yourself naturally drawn to skunks over mongooses. However, if you are a pet fence sitter like I am, you will be aware that both branches of the carnivora have a lot to offer. The enormous diversity of relatives of cats and dogs attests to the successful evolutionary “design” that these two most popular pets share.
* The giant “panda” and red “panda” are not biologically related. The red panda is the only member of its own unique branch of Carnivora, known as Ailuridae, while the giant panda is actually a bear (Ursidae). Nearly 50 years after the red panda was first made known to westerners in the 1820s, the giant “panda” was given its western name and mistakenly believed to be related to it. So I must ask: Are you a giant “panda” person or a red “panda” person?
Flynn JJ, Finarelli JA, Zehr S, Hsu J, Nedbal MA. 2005. Assessing the Effect of Increased Sampling on Resolving Mysterious Relationships in the Molecular Phylogeny of the Carnivora (Mammalia) Journal of Systematic Biology 54:317-337.
It includes Ottoni C, Neer WV, De Cupere B, Daligault J, Guimaraes S, Peters J, Spassov N, Prendergast ME, Boivin N, Morales-Muiz A, Bălăşescu A, Becker C, Benecke N, Boroneant A, Buitenhuis H, Crowther A, Llorente L, Manaseryan N, Monchot H, Onar 2017. The palaeogenetics of cat dispersal in the ancient world. Nature Ecology & Evolution 1:0139.
Hogan A, Brubaker L, Wanser S, Stahler D, Wynne CDL, Ostrander EA, Sinsheimer JS, Udell MAR, vonHoldt BM, Shuldiner E, Janowitz Koch I, Kartzinel RY, 2017. Stereotypical hypersociability is caused by structural variations in genes linked to the human Williams-Beuren syndrome in domestic dogs. Science Advances 3:E1700398.
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FAQ
Is a dog a living organism?
Living things eat, grow, breathe, move, reproduce, and have senses. Example of the living thing is a dog. Dogs are animals, and as such, they require food, water, space, and shelter.
Is any animal an organism?
A living thing with an organized structure, the capacity to respond to stimuli, reproduce, grow, adapt, and maintain homeostasis is referred to as an organism. Consequently, an organism would be any earthly animal, plant, fungus, protist, bacterium, or archaeon.
What is a dog classified as?
A dog is a domestic mammal that belongs to the order Carnivora and family Canidae. Its scientific name is Canis lupus familiaris.
What is in a organism?
Organ systems, tissues, cells, and tissues are the four levels of organization that make up living things.