Dog Domestication: An Ancient Friendship Between Man and Beast.
Have you ever looked at man’s best friend and wondered how, or when, that friendship began? I look at my two “kids” and wonder how long humans as a species have relied on this canine companion for not only friendship, but protection and sustenance as well. They have been family members, protectors, and hunting partners to countless generations.
Recently, scientists have been attempting to utilize genome sequencing to put a count on those generations. The results have been surprising. Human history and canine genealogy seem to have run parallel for much longer than originally thought and originated in a different location than previously believed.
There are two schools of thought on the origin of the dog. Some believe that the evidence points to the dog being domesticated first in the Middle East or East Asia. Others argue for their domestication first in Europe. Recently, scientists have been using advancements in genetics to trace the genome of canis familiaris.
There is a traceable relationship between modern dogs and European wolves with ancient European canids. Also, the fact that there have been no remains found outside of Europe older than 13,000 years further indicates a European origin.
The dates found in Europe, dating 18,800–32,100 years ago, put dog domestication before agriculture. This means that man’s earliest best friend was running alongside hunter-gatherers hunting now-extinct megafauna.
The DNA from these fossils shows a common ancestor between our modern dogs and wolves as an extinct wolf-like canid. In other words, our modern dog is not a descendant of the wolf, but rather the two of them are both descendants from a completely different animal, a kind of primeval amalgamation.
The fact that the dates span 10,000-15,000 years is also explained by the DNA data as domestication being multiregional with different dog breeds being started at different times with no single place of origin. The European domesticate just happens to be the oldest fossils found.
A study done in 2013 by Olaf Thalmann, an evolutionary geneticist at the University of Turku in Finland, and Robert Wayne, an evolutionary geneticist at the University of California, Los Angeles, puts domestication to 20,000 to 30,000 years ago. They sequenced the genomes of mitochondria from 18 samples ranging from 1,000 to 36,000 years old and created a family tree. This sequence again pointed to a European common ancestor.
One of the fossils studied was a partial rib-bone of a wolf found near the Bolshaya Balakhnaya River in Siberia. Radiocarbon dating put this animal around 35,000 years old. The genome sequencing indicated that our modern dog, the gray wolf, and this extinct wolf from Siberia, dubbed the Taymyr wolf, diverged about the same time from a common ancestor.
Another 33,000-year old fossil from Razboinichya Cave in the Altai Mountains of southern Siberia was more closely related to modern dogs than to contemporaneous wolves. This is further evidence of ancient dogs and ancient wolves diverging much earlier than previously thought from a common ancestor.
This is not to say that dogs themselves were domesticated at this time, but that their ancestor that was distinctly “dog” starts to show up at this time. This suggests a physical separation from the wolf population that resulted in an entirely new line. This gives an estimation of domestication; otherwise the two lines would have mixed and wouldn’t show up so clearly as independent lineages.
Many scientists believe that dogs were repeatedly domesticated and that even then still occasionally interbred with wolves. This is why some domestic breeds are closer to their wolf cousins than others, such as Siberian Huskies and Greenland dogs.
When looking at the Taymyr wolf and modern dogs, the genome showed that some breeds are closer to either the grey wolf or the Taymyr further evidencing that modern dog breeds originated in many different regions
But How Was It Done?
Now that we’ve covered where the dog seems to have been first domesticated, the question of how it may have been accomplished comes up. One hypothesis is that dogs domesticated themselves. The idea is that some prehistoric wolves scavenged the trash heaps and/or kill sites of prehistoric humans. Keeping in close proximity to these settlements and following the nomadic humans, these canids gradually evolved into the first domesticated dogs. The only problem with this hypothesis is that there have been wolves scavenging around human settlements for centuries without showing the slightest inclination towards domestication
Another hypothesis is that humans deliberately tamed dogs. There are many ideas as to why they might have done this ranging from practical reasons, such as hunting tools or garbage clean-up, to possible ceremonial uses. From these animals, certain behavioral traits could be bred into future generations to become the first dogs. The arguments against this include researchers attempting to tame wolf pups this way and finding that after 21 days of age, the process was very time-consuming and often unsuccessful. Some wolves can be kept as pets, but they are still wild and cannot be considered as fully domesticated.
Regardless of how it was achieved, the dog domestication process has produced changes in both species, human and canid. The DNA sequencing studies have shown the change being most apparent in the genes for digestion and metabolism. Compare the differing diets between dogs and wolves. Wolves eat more meat, while domesticated dogs require a diet richer in carbohydrates. The first dogs may have followed hunter-gatherer humans in the hunt, but later dogs have evolved alongside agricultural humans, therefore their diet moved away from being so protein-heavy.
The Love Connection
Also, there’s that indefinable connection between dogs and their humans that goes beyond biology. Recent studies have shown that extended interaction between dogs and their owners increases oxytocin levels in both. This chemical is known as the bonding hormone and can be considered a result of the co-evolution of humans and dogs. This is why so many dog owners refer to their dogs as children; oxytocin is the same chemical mother’s produce when looking at their babies.
There is much evidence pointing to the co-evolution of man and his best friend. Even our closest genetic relative the chimpanzee doesn’t as closely resemble our behavior patterns as do canines. Group cooperation is almost non-existent in other primates except for occasional hunting excursions or ganging up on a common enemy.
Contrariwise, we have many societal traits in common with wolves. Pack hunting is a distinctly canine behavior. Early humans moved from small game hunting and scavenging to hunting big game and living in larger groups around the same time they were domesticating dogs. Coincidence? Humans also started marking their territory with cave paintings. The communal hunting led to communal defense and territoriality much like wolves scent-mark and actively patrol their lands.
There are other similarities as well. Packs consists of monogamous pairs, but all members share food and baby-sitting duties – it takes a village to raise a child. Greater risks can be taken when hunting because if someone gets hurts, they know they will be taken care of until healed by the rest of the group. This also leads to close friendships within the group. These are all traits that canines and humans share.
With so many similarities and a history that spans over 30,000 years, is it any wonder why we’re so attached to our furry friends? Anyone who owns a dog will tell you that they are not a pet; they are a member of the family. This tradition has history and is rooted in our species’ oldest memories. It was vital to our early survival and remains important to our emotional well-being now. Service dog anyone?
Which breed of dog is your favorite?
© 2015 chavaj