By comparing genomic signatures from 71 mitochondrial and seven nuclear genomes of ancient North American and Siberian dogs spanning a period of 9,000 years, the research team was able to gain a clearer picture of the history of the first canine inhabitants of the Americas. The oldest dog remains in the Americas date to about 9,000 years ago... These dogs persisted for thousands of years in the Americas, but almost completely vanished after European contact, the researchers found... The team also discovered that the genomic signature of a transmissible cancer that afflicts dogs appears to be one of the last...