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This is the skull of a Razboinichya canid

Dogs: Their Fossil Relatives and Evolutionary History

Archaelogical sites have determined that the earliest fossil evidence of domestic dogs date back to 12,000-14,000 years ago in Eurasia and some genetic evidence dates back to 100,000 years ago in east asia. The family canidae is the group of carnivores that includes animals like wolves, foxes, jackals, and hunting dogs. The group carnivore also includes the domestic dog’s ancestor, the canid. These fossil relatives date back to the late Eocene, which means they date back to more than fourty million years from the present day. The dog is the first fully domesticated animal in human history. . There are more than 214 species of canids that have been discovered and thirty seven of those species still remain today.

Features of First Canids

Canids, the fossil relatives of dogs, originated more the fourty million years ago in the late Eocene. Because of their Carnassials, canids are members of the order Carnivora. Carnissials are long, sharp teeth that function to cut into bone. Canids first originated in North America, but during the Miocene, seven to eight million years ago, they were able to cross the Bering straight into Europe. The first domesticated dog fossil was found in northern Israel. Archaeologists uncovered a site dating back to the Natufian period, which is 12,000 to 10,000 BP. A fragment of a mandible containing a carnissial of an older canid with the remains of a puppy were found buried with a human, in a human’s grave. The human’s hand was placed on the head of the remains of the canid, suggesting a loving relationship. The first fossil relative of the dog arose in North America during the early Paleocene, around sixty to sixty-five million years ago. It belongs to the family Viverravidae. It possed true carnassial teeth. It had a ten centimeter long skull, indicating that it was small in size. The second found and increasingly larger fossil ancestor appeared in the early Miocene, around twenty-three million years ago. They belong to the family Amphicyonidae. Their common name is the “bear dog.” The Amphicyonidae have the elongated legs and feet that are recognized on present day dogs. The third fossil relative is a member of the family Mesonychid. They were found in the middle Eocene. The viverravids and amphicyonids are cat or fox sized predators, but the Mesonychids are wolf sized and are easily able to take on larger prey. They have skulls up to one meter long with massive bone crushing teeth. These three fossil ancestors show a evolutionary trend of increasing body size and more “hypercarniverous” acts because of their carnassial teeth growing larger and sharper, leading to what we know today as the modern domestic dog.

Domestication Experiments

The evolution of canids begin with the previously mentioned evolutionary trend of increasing body size. In 1997, Carles Vilà determined, through genetics, that the wolf and domestic dog had a speciation event 135,000 years ago. His conclusion was made by looking at base pair sequences to determine the number of substitutions in mitochondrial DNA, with the assumption that the mutations were happening steadily. Taming is very distinct from domestication. Domestication effects genetic makeup of the animal, making it heritable. There are five evolutionary changes that some domestic dogs have been introduced to: one, being selection by humans for reduced aggression. Two, being the need for the canids to reproduce well around the presence of humans, mostly for artificial selection. Three, the usefulness behavior of the dog being selected on for working needs. Four, traits that are useful in work such as hearding behaviors. Five, physical attributes for specialization of breeds in order to achieve different utilities. Those five aspects have caused multiple evolutionary changes in a canids, coat, teeth, and diet. The coat of a canid, because of domestication, has changed from a form of camoflauge to the present piebald form. The coat has also become increasingly longer with the canids ear becoming increasingly floppier. The carnissial teeth of the canid have evolved to be shorter, causing a widened snout and more compressed jaw. The canid’s diet has also evolved through domestication. The dog’s fossil relatives cannot process starch. They lack the amylase gene AMY2B. Modern dogs posses AMY2B, allowing them to digest starch. This was a critical evolutionary response for domestication. These evolutionary aspects were critical for divergence of the wolf and the dog .