Dog Divergence and Evolution

Dog Divergence

• Domestic dogs are considered the same species as wolves, and their evolutionary history includes some interbreeding.
• Mitochondrial DNA, or mtDNA, is a type of genetic material found in mitochondria, which are organelles within cells.
• The divergence timeline of domestic dogs from wolves has been reduced from 135,000 years to 30-40,000 years due to improved fossil evidence, DNA sequencing techniques, and analysis of nuclear and mtDNA.
• mtDNA is passed down through the maternal lineage, meaning that it only comes from the mother's eggs.
• mtDNA studies show that dogs and wolves have interbred at various times, with wolves contributing mitochondrial DNA to dogs.
• North American dogs likely evolved from Eurasian wolves, reaching the Americas around 12,000 years ago.
• Dingoes, a type of wild dog found in Australia, are believed to have been brought to the continent by seafarers around 4,000 years ago.
• Dingoes are descended from domestic dogs and are not a separate species. They have remained isolated in Australia, which has contributed to their feral nature.

Dingo Origin

• The dingo is a feral dog that is a descendant of domestic dogs.
• The dingo was likely brought to Australia by seafarers approximately 4,000 years ago.
• Dingoes have been valued by Indigenous Australians as companions, hunters, and guard dogs.
• The dingo is thought to have competed with the thylacine, the largest known carnivorous marsupial, leading to its extinction.

Dog Domestication

• Domestication is the process of adapting wild plants and animals for human use, involving control over their reproduction and care.
• Archeological records suggest that numerous domestic dog ancestors were domesticated near the Fertile Crescent, likely due to the advent of agriculture.
• The domestication of dogs may have occurred before the domestication of sheep, goats, and cattle.
• Theories on how wolves were domesticated include the commensal theory, where wolves benefited from scraps left by humans, and the intentional capture and rearing of wolf pups by humans.

Wolf Domestication Theories

• The commensal theory suggests that wolves were initially attracted to human settlements for scraps.
• The theory posits that less aggressive wolves were more likely to benefit from this, while aggressive wolves were driven away or killed by humans.
• This theory suggests that the social nature of wolves, with their pack structures and communication, aided in their domestication.
• An alternative theory suggests that humans actively captured wolf pups, which would have led to the development of strong bonds between humans and these wolf pups.

Acceptance and the Silver Fox Experiment

• Acceptance is a change in behavior without changes in DNA sequences, often observed in captive-bred animals.
• Domestication involves changes in DNA sequence, leading to altered behaviors and relationships with humans.
• The Silver Fox experiment, conducted by Dr. Dmitri Belyaev, demonstrated that selective breeding for tameness could lead to both behavioral and physical changes in foxes.
• This experiment supports the idea that selection for certain traits, like docility, can also lead to the selection of physical characteristics, indicating a connection between neural crest cell development and both behavior and morphology.

Archaeological Evidence

• The Oberkassel site in Germany contains a 14,200-year-old domestic dog mandible found near the graves of two humans, providing evidence for early dog burials.
• A Natufian burial site about 12,000 years old showcases a human buried with a dog, indicating a close relationship and likely dog use in hunting.
• Petroglyphs in Saudi Arabia dating back thousands of years depict humans and dogs together, with representations like curled tails suggesting the presence of domestic dogs and highlighting the interaction between humans and dogs in hunting.

Ancient Domestication Evidence

• Wolf skulls with shortened facial regions found near Fairbanks, Alaska, dating back to the end of the Last Ice Age, suggest the presence of "tamed wolves".
• Ancient Egypt offers plentiful evidence of dog domestication, with dogs found in households, tombs, and burials.
• Dogs in Ancient Egypt were considered companions, and even royalty were buried with their dogs. The Egyptian god Anubis, with the head of a jackal, guarded the afterlife.
• Archaeological evidence suggests the use of dogs for hunting, companionship, and religious purposes in Ancient China dating back 6,000 to 7,000 years.
• Dog bones were also used as oracle bones in Ancient China, demonstrating their cultural significance.
• In Mesoamerica, dogs played a similar role to Ancient China, serving as a source of protein for large populations.
• The Assyrian Empire, about 2,500 years ago, utilized mastiff-like dogs for hunting lions and other prey.
• Ancient Greece also recognized the value of dogs, utilizing them as sheep guardians, guard dogs, and tracking dogs.