Dogs in America: Study of Ancient Dog Migration

Dogs in America - Study of Ancient Dog Migration

Dogs in America - Study of Ancient Dog MigrationCynology is becoming more popular as a true scientific field, and more research is underway for humans to expand their knowledge on the history of a man’s best friend. Previous research shown the connection between ancient dogs and women, and now a new study suggests a possibility that those dogs in America might have migrated here no sooner than 10,000 years ago – far later after the humans have inhabited this land.

Previously, researchers have suggested that humans have migrated to the Americas about 25,000 years ago, crossing the bridge of land from Siberia to North America. But the most recent evidence shows that first Americans actually came here 15,000 years ago. Now scientists also say that our species’ most trusted companions, who most likely looked like today’s dingoes (Canis lupus dingo), have joined us a little later. These findings have been recently published in the Journal of Human Evolution [1].

This new study has assessed DNA characteristics of 84 different canines taken from different parts of the Americas, from North to South, and it was concluded that dogs quickly learned to adapt and live alongside humans. Unlike their predecessors wolfs, ancient dogs in America learned to tolerate humans and took advantage of the benefits that come out of partnership with a more intelligent species. Similarly to our world of today, dogs would receive food, shelter and safety in exchange for their loyalty.

Dogs in America Study of Ancient Dog Migration Dingoes
Ancient dogs in America looked like dingoes, study says / Photo credit: Tim Williams

Their 11,000 – to 16,000-year association with humans makes canines a promising subject for the study of ancient human behavior, including migratory behavior, said University of Illinois graduate student Kelsey Witt, who led the new study analysis with anthropology professor Ripan Malhi.

“Dogs are one of the earliest organisms to have migrated with humans to every continent, and I think that says a lot about the relationship dogs have had with humans. They can be a powerful tool when you’re looking at how human populations have moved around over time,” said Witt in the press release.

Human remains are not always available for research because, according to Witt, “living populations who are very connected to their ancestors in some cases may be opposed to the destructive nature of genetic analysis.” Analysis of ancient dog remains is often permitted when analysis of human remains is not, she said.

Previous studies of ancient dogs in America focused on the dogs’ mitochondrial DNA, which is easier to obtain from ancient remains than nuclear DNA and, unlike nuclear DNA, is inherited only from the mother. This means mitochondrial DNA offers researchers an unbroken line of inheritance back to the past.

The new study of dogs in America also focused on mitochondrial DNA, but included a much larger sample of dogs than had been analyzed before.

Molecular anthropologist Brian Kemp of Washington State University provided new DNA samples from ancient dog remains found in Colorado and British Columbia, and the Illinois State Archaeological Survey (ISAS) provided 35 samples from a site in southern Illinois known as Janey B. Goode, near present-day St. Louis. The Janey B. Goode site is located near the ancient city Cahokia, the largest and first known metropolitan area in North America. Occupation of the Janey B. Goode site occurred between 650 and 1,400 years ago, the researchers said, while Cahokia was active from about 1,000 to 700 years ago.

Dozens of dogs were ceremonially buried at Janey B. Goode, suggesting that people there had a special reverence for dogs. While most of the dogs were buried individually, some were placed back-to-back in pairs. In Cahokia, dog remains, sometimes burned, are occasionally found with food debris, suggesting that dogs were present and sometimes were consumed. Dog burials during this time period are uncommon.

Dogs in America Study of Ancient Dog Migration
Ritualistic burial of two dogs, possibly 1350 years ago / Photo credit: Illinois State Archaeological Survey

As previous studies had done, the Illinois team analyzed genetic signals of diversity and relatedness in a special region (the hypervariable region) of the mitochondrial genome of ancient dogs from the Americas. University of Iowa anthropology professor Andrew Kitchen contributed significantly to this analysis of dogs in America.

The researchers found four never-before-seen genetic signatures in the new samples, suggesting greater ancient dog diversity in the Americas than previously thought. They also found unusually low genetic diversity in some dog populations, suggesting that humans in those regions may have engaged in dog breeding.

In some samples, the team found significant genetic similarities with American wolves, indicating that some of the dogs interbred with or were domesticated anew from American wolves.

“But the most surprising finding had to do with the dogs’ arrival in the Americas. Genetic diversity of dogs in America may date back to only about 10,000 years ago,” said Witt.

“This also is about the same time as the oldest dog burial found in the Americas. This may not be a coincidence,” added Malhi.

The current study, of only a small part of the mitochondrial genome, likely provides an incomplete picture of ancient dog diversity in the Americas.

“The region of the mitochondrial genome sequenced may mask the true genetic diversity of indigenous dogs in the Americas, resulting in the younger date for dogs when compared with humans,” concluded Malhi.

More studies of ancient dogs are in the works, the researchers said. Witt has already sequenced the full mitochondrial genomes of 20 ancient dogs, and more are planned to test this possibility, the researchers said.

 

References:

  1. Kelsey E. Witt, Kathleen Judd, Andrew Kitchen, Colin Grier, Timothy A. Kohler, Scott G. Ortman, Brian M. Kemp, Ripan S. Malhi. DNA analysis of ancient dogs of the Americas: Identifying possible founding haplotypes and reconstructing population histories. Journal of Human Evolution, 2014; doi: 10.1016/j.jhevol.2014.10.012