The following article, which is published in the latest edition of the Creature’s Corner News, was written by our LiHigh School middle-schoolers: Ariah, Cassidy, Colleen, Lizzy, and Tooti. The article is the final product of a weeks-long research project on the evolution of canines. If you’re interested in the topic, our students will be giving a presentation of their research on Friday morning, at 10:15, here in the classroom, and the public is invited to attend.
At LiHigh School in Poultney, the middle-school students wondered how the domestic dog evolved and humanity’s role in that process. Most of the middle-schoolers have dogs and all love animals, so their interests drove this research question. The first task was to understand what, exactly, canines are.
There are about 40 species in the Canidae family, including foxes, jackals, wolves, and dogs. 45,000 years ago, millions of Canidae lived throughout the world. Today only about 160,000 wolves roam the world, showing how far wild Canidae have declined.
To understand where wolves and other canines came from, we need to look further back than 45,000 years ago. Canines evolved as carnivores, but carnivore-mammal evolution also included bears, felines, weasels, etc. The first known carnivorous mammal was Cimolestes, a half-pound creature that lived 60 to 70 million years ago. Although Cimolestes was the first carnivorous mammal, modern carnivorous mammals descended from the weasel-sized Miacis, which lived about 55 million years ago. About 5 million years later, the Miacis divided into many types of carnivores, each of which evolved along their own paths.
One of those groups, the Canidae, split into subfamilies, with the first clearly identifiable members evolving about 40 million years ago. Some of these were Prohesperocyon, Hesperocyon, and Leptocyon. The identity of the first true canine is still being debated, as is the species that modern canids evolved from, but we do know that they originated in North America, and that, about 10 million years ago, they crossed the land bridges into Eurasia and South America.
Perhaps the most famous of these early canids is the dire wolf, which inhabited both North and South Americas from about 2 million years ago to 10,000 years ago, when it went extinct. The dire wolf weighed 200 lbs. and competed with the saber-toothed tiger for prey.
The wild ancestor of today’s domestic dogs, the gray wolf, probably evolved in Asia and migrated to America, where it lived alongside the dire wolf. We know the domestic dog evolved from the gray wolf starting about 15,000 years ago.
When people followed the buffalo and other herd animals, they threw the waste and leftover meat to the side of their camps. Seizing the opportunity for easy food, the wolves started to hang around the camps, but only the more social wolves survived (humans killed the aggressive ones). The friendlier wolves broke from the pack to follow the humans when they traveled. These wolves would also alert the humans to any danger, which earned our trust. The human-friendly wolves formed their own packs and stopped mating with the more aggressive packs. Eventually, they became their own species.
Now called “proto dogs,” this new species began a partnership with the humans. The humans found that the proto dogs were fantastic hunters, and later, fantastic herders. The dogs’ gift for herding allowed humans to stop following the herds and build the first settlements. The amazing bond between humans and dogs had grown, and they have been helping us ever since, truly earning the title of humanity’s best friend.
Over the generations, humans have selected and refined the characteristics of dogs through breeding, aiming to create perfect breeds. For example, we’ve bred herding dogs so that they have high energy and focus levels and are very motivated by prey; hounds so that they are easy going and scent motivated; and terriers so that they are very quick and intelligent.
There is a downside to breeding, however. We breed these skills by creating a closed gene pool, where hounds are bred with hounds, terriers with terriers, etc. This allows us to enhance the skills we’re looking for, but it also allows dangerous mutations to flourish. For example, Dalmatians have beautiful spots thanks to these closed gene pools, but they are also prone to deafness for the same reason. Some modern breeders are attempting to solve these problems, but it is still a significant issue for many dogs.
Now that the middle schoolers are more aware of the long journey their dogs have traveled —from crossing the land bridges to helping humanity with herding and hunting to becoming lovable companions — the middle schoolers have developed an even stronger appreciation for their labrador retrievers, terriers, pugs, hounds, golden retrievers, chihuahuas, and shepherds. They hope you have developed a newfound appreciation for your dog as well.