American dog breeds came from Asia, finds genetic study
A study of dog breeds in the Americas indicates that they migrated along with humans from East Asia, and that their genetic legacy has persisted to the present.
When Christopher Columbus arrived in Cuba in 1492, he took note of the indigenous domesticated dogs, which the Taíno people called aon. The aon did not bark; according to Columbus, they just whistled, howled, and chortled.
Two years later, faced with starvation, Spanish settlers on La Isabela, the the first formal European settlement in the New World in what is today the Dominican Republic, the Spanish would eat the aon. Other native dog breeds were wiped out by diseases from Europe.
Previously, it was thought that America's original dogs were wiped out, replaced by European breeds that arrived with the conquistadors and their successors. That's what genetic studies of some wild dog populations in the Americas had concluded. But recent research indicates that these original American domestic canines, whose ancestors arrived with the first Americans tens of thousands of years ago, have a legacy that continues today.
In a study published in the Proceedings of the Royal Society B, an international team of researchers examined mitochondrial DNA drawn from the blood or swabbed from the cheeks of American dogs such as the Chihuahua, Arctic sled dogs, and the Peruvian and Mexican hairless dog breeds. They compared these data with those from Asian and European breeds, as well from dog remains found at ancient American archaeological sites.
A mitochondrion is a tiny structure inside a cell that, among other important functions, helps convert the chemical energy from food into usable fuel. It has its own DNA, called mtDNA, which is inherited in most species, including dogs and humans, exclusively from the mother.
"You can follow a lineage back in time indefinitely," Peter Savolainen, a researcher from the KTH Royal Institute of Technology in Stockholm, Sweden, and a coauthor of the study told to the Monitor in a telephone interview.
Dr. Savolainen and his colleagues found that, among these breeds, only about 30 percent of their mtDNA had been replaced by that of European breeds. The rest had its origins in East Asia.
A subspecies of the gray wolf, the dog – Canis lupus familiaris – is humankind's first domestic species. There is some evidence of limited domestication of – or at least cohabitation with – wolves as early as 33,300 years ago. But a 2002 mtDNA study led by Savolainen shows that the domestication of dogs began in earnest in villages in what is today southern China about 15,000 years ago. Savolainen also co-wrote a 2010 study of dogs' Y-chromosomes, which are passed father to son, that supports southern China as the locus of domestication.
Savolainen, who as a master's student in 1993 hit upon using mitochondrial DNA from dog hairs in an attempt to solve a murder, says the practice of domestication radiated outward from China to the Middle East, Africa, Europe – and across the Bering land bridge to the Americas, where the dogs' ancestors eventually became the Taínos' beloved aon.
Today, domestic dogs are found in cultures all over the world. "I think you can put together dog genetics and human genetics and tell a larger story," says Savolainen.