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The Evolutionary Timeline of a Dog by Jack Chmura and Beau Farris
Transcript of The Evolutionary Timeline of a Dog by Jack Chmura and Beau Farris
Domestic dogs evolved from a similar group of ancestors that wolves had. These ancestors came into contact with European hunter-gatherers between 18,800 and 32,100 years ago and may have since died out. Canis lupus (wolves) of these times were carnivores with large jaw muscles and large teeth. They developed big teeth and strong jaw muscles because of how they hunted and killed their prey (by tearing and ripping with their mouth). Their muscles were not as strong as their earlier ancestors Amazing scent was also helpful for the wolf to hunt. The ancient wolf had a think coat of fur that was came from the harsh ice age that came upon the world. Wolves hunted in packs because of their position on the predator chain and how easy it was to hunt in packs. Wolves got domesticated by eating out of human trash piles and being friendly to humans to get more food. This all happened over thousands of years. This change was not instant.
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Around 150 years ago humans pure bred domesticated dogs to get traits that were desirable. Certain traits bred for today are fur color, fur thickness, overall breed, energy level, aggression, hole digging, howling etc. The way to breed the dogs together is through selective breeding. Humans put two dogs with desirable traits together to mate and make offspring that has a combination of both traits. The humans made these traits appear. They would have likely not came naturally.
One of the first dog like genus on Earth was the Tomarctus. Though not able to be proven by DNA evidence this species looks and acts like the ancient wolves(aggressive and territorial). It lived on Earth around 6.8 million years ago. The species had long tails for balance, sharp claws for killing prey and very strong jaw muscles. One conclusion made is that this species ate bones for nutrition because they weren't top of the predator chain.
Borophagus is the next known dog like genus to live on Earth. It lived around 2.5 million years ago. Since it wasn't the main predator of the time, it had to eat the leftovers from other stronger predators who actually killed their prey. This included bones and tough meat. The Borophagus had strong chewing muscles and huge jaws. They looked hyena like. Due to their position on the predator chain they had to develop stronger jaw muscles to be able to survive on the leftovers.
Wolf bones were found in many human burial grounds, thus showing the domestication of the wolf was influenced by humans. In Sweden dog bones were found in an ancient human cemetery where dogs were buried alongside children. These fossils provide evidence for the domestication of dogs by humans and how dogs got close to humans and how close humans got to dogs.
When wolf DNA was compared to certain breeds of domesticated dog DNA they came out very similar with some only having a 2.5% difference. Just like humans and monkeys, dogs don't evolve from wolves. They just share a similar ancestor. Nuclear DNA points out divergence of the species about 11,000-16,000 years ago. DNA helps support the theory of dogs evolving from similar ancestors of wolves.
Over time wolves evolved to have passive traits. Their teeth became smaller, similarly with their jaw muscles. Humans and dogs became closer. The wolves became less aggressive and less territorial over time. One major explanation for this change to being a more passive species was, how easy it was for wolves now dogs to get food. Instead of hunting in packs, they would be fed by humans. This was way easier for the dogs/wolves, and it provided more nutrition.
Change Over Time
1.The Borophagus developed strong jaw muscles because they were not able to fight other predators. They had to eat the leftover bones and tough meat. This provided a selective advantage because they would not have to fight other predators and die trying to get food.
Wolves adapted to living around and being less aggressive towards humans to be able to get "free" food from trash piles. This adaption provided a selective advantage because the wolves didn't have to hunt as much and got more nutrition. Free food is better then food that needs work.
2. The evolution of wolves into dogs was effected mostly by the human race. Humans were able to domesticate the wolves and use them to help hunt. Because of the human impact on the wolves, wolves became less aggressive and less territorial. Wolves got free food from humans and that was easier then hunting. The type of food in the environment and how the food is acquired changed the jaw muscles and tooth lengths to both become smaller.
3. I think that the evolutionary line will not diverge. There will be two types of dogs in the future: the mutts who live in the streets who are considered healthier and the pure bred dogs that have perfect traits. These perfect traits will become truly perfect and little change will happen to them over time. The mutts are more resistant to diseases so they will have a selective advantage if a disease comes in the future that effects dogs. Another prediction is that in the future dogs might even evolve to be independent from humans causing traits to revert back to the way they were in the past. This might be caused by humans ignoring the dogs.
Cynodictis is known to be the grandfather of the dog. These "bear" dogs had fairly brushy coats of fur and looked a lot like a fox. Bones of these animals were found in Africa. This species lived 37.2-28.4 mya.
Daphoenus also belonged to the bear, wolf, fox, dog family. This animal had small legs and looked like a small fox. It had small bursts of fast speed thus not being able to hunt prey. They had to ambush their prey. They lived 40-25.7 mya.
This prezi shows how wolves adapted and evolved over time to get to the stage of dog, but it is key to know that dogs didn't evolve from wolves. They share a similar ancestor. Modern day wolves are important to mention because they are a second genus that evolved from that similar ancestor. A few changes that occurred since the ancient wolves are a smaller coat of fur because over time it got warmer, smaller teeth because its prey wasn't and isn't as hard to kill. Canis lupus still has a good scent of smell, and it hunts in packs. A smaller set lets them run faster as well. Today the species of Canis lupus lives in the wild and are not domesticated.
As seen here the modern dog shares many similarities with ancestor the cynodictis. One notable change is the placement of the eyes, making the dogs have a more binocular vision like humans. Another change seen is the length of the hind legs, and location of the pelvis. The dogs are longer, making it more suited for running and jumping, instead of digging.
The top skull is a modern dog, while the bottom skull is a tomarctus skull. The major development here was the movement of the eyes from the side of the head, to the front of head, giving the dog binocular vision to lock on to prey, as well as avoiding predators. Another noteworthy development in the increased length of the palate ratio.
As seen on the Borophagus skull, the length of jaw has increased dramatically, to better pull off meat, and the molars in the back of the mouth have developed as well, getting us closer to the modern day dog. You can also see where the jaw muscles would connect to to top of the skull, where there is a slight ridge