Kashmiri Pandit
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A new study reveals that the origin of man’s best friend may not have been where, or when, the scientific community previously believed. The analysis of a variety of ancient canine DNA has also helped researchers create a map of the journey of the domestic dog across the world.
This is believed to be the most complete study of dog genomes to date, and as the researchers wrote in their article published online in the journal Cell Research, “For the first time, our study unravels an extraordinary journey that the domestic dog has traveled on earth.”
Peter Savolainen of Sweden's KTH Royal Institute of Technology, and one of the contributors to the current study’s international team, told Phys.org that while past studies also analyzed the entire nuclear genome, they failed to include samples from South East Asia – following the general belief that domesticated dogs had originated in the Middle East, Central Asia, or Europe.
This time the researchers conducted a DNA analysis using samples from more regions of the world and different time periods. They used this information to look for series of admixtures (events that occur when individuals from two or more separate species begin to interbreed). The results of their study have led them to assert that domesticated dogs most likely descended from gray wolves in South East Asia, about 33,000 years ago. Furthermore, they claim that the “founder population” numbered approximately 4,600 canines.
A gray wolf. (Gunner Ries/CC BY SA 3.0)
The sample was composed of genomes from 58 canids. Specifically, the scientists analyzed DNA from:
“Dogs from Central Asia (Afghan Hound) and North Africa (Sloughi), Europe (eight different breeds), the Arctic and Siberia (Greenland dog, Alaska Malamute, Samoyed, Siberian Husky, and East Siberian Laika), the New World (Chihuahua, Mexican and Peruvian naked dog) as well as the Tibetan Plateau (Tibetan Mastiff). These dogs were chosen to cover as many major geographic regions as possible.”
Geographic locations of the 58 canids sequenced in the study. (Guo-Dong Wang, et. al)
Through their research, they have also provided an explanation for the migration of the domesticated dogs to the rest of the world:
“Around 15,000 years ago, a subset of ancestral dogs started migrating to the Middle East, Africa and Europe, arriving in Europe at about 10,000 years ago. One of the out-of-Asia lineages also migrated back to the east, creating a series of admixed populations with the endemic Asian lineages in northern China before migrating to the New World.”
Three of the dog breeds that were chosen for the DNA study: Siberian Husky (CC BY SA 3.0), Tibetan Mastiff (CC BY SA 3.0), and Peruvian naked/hairless dog (CC BY SA 3.0)
The reasoning for the delay in migration may have been due to climatic conditions. Ya-Ping Zhang of the Chinese Academy of Sciences Kunming Institute of Zoology, and one of the co-authors of the current study told Discovery News: "For some reason, dogs stayed around East Asia for a long time before their migration out of Asia. We speculated that the glacial period might have been the environmental factor that prevented dogs from migrating out of Asia."
A proposed migratory history for domestic dogs across the world based on the evidence from the current study. Solid arrows show migratory tracts with complete dating information and dashed arrows indicate those without accurate dating. (Guo-Dong Wang, et. al)
Although it is probable that the migration of dogs and humans were often interconnected, the recent study suggests that the first movement may have been chosen first by the canines, and not their human companions.
As for the path to domestication, it has been said that the current research provides evidence for three main stages, instead of the former assumption of two: pre-domesticated scavengers that had loose contact with ancient humans, then closer human-dog interactions that led to domesticated “non-breed dogs,” and finally human selection for specific traits in dogs – selecting and creating breeds.
Savolainen told The Telegraph that the domestication process was not quick, and that it could have been created by “[…] waves of selection for phenotypes (mutations) that gradually favored stronger bonding with humans, a process called self-domestication.”
A German Shepherd dog. (Public Domain) The German Shepherd is a relatively new breed of dog, that is often prized for its strength, intelligence, trainability, and obedience.
While the results of the current study are intriguing, the debate still continues on the origins of man’s best friend - a 2011 study of a 33,000-year-old skull of a partly domesticated dog found in a cave of the Altai Mountains of Siberia have led scientists to that area. However, the high genetic diversity of canines in Central Asia, as reported in a study released in October, has suggested Nepal or Mongolia for the beginnings for humanity’s loyal companion.
Additionally, analysis of an ancient wolf’s bones (also from Siberia), published in May state that the genetic split from wolves to dogs began sometime between 27,0000 – 40,000 years ago - although the scientists from this study acknowledged that these wolf-dog hybrids may not have been domesticated until later.
