Domestication of the dog
Asaf Shany
Kingdom-Animalia
Phylum-Chordata
Subphylum-Vertebrata
Class-Mamalia
Order-Carnivora
Family-Canidae
Species-Canis lupus familiaris.
“Wild dog crawled into the cave and laid his head on the woman’s
lap… And the woman said: “his name is not wild dog any more , but
the first friend” “( Rudyard kipling ‘just so stories’).
Where did our best friend come from?
There are more than 300 domestic purebred dog breeds around the world. Did you
ever ask yourself when or where these dogs came to be our closest companions?
Like a lot of other scientific questions, the answers to these ones are still
under debates.
The wolf( Canis lupus) – The dog ancestor.
One question can be answered without a doubt(?). Our best friend ancestor is
the wolf.
Wolf bones found near different Homo spp. (early man) bones dating back 400,000
years in Britain, 300,000 years in China, and 150,000 years in France were dismissed
as signs for domestication, and were considered as signs that the wolves were
used as food for early man and not for companionship. Was it true to dimiss
these findings?
Hypothesis 1- domestication started in the Middle East.
An early and genetically unproved hypothesis, stated that the domestication
started in the middle east, around the area of Israel. The dog breed Knaani
(Knaan= ancient Israel) was thought to be the first purebred dog in the world
(suggests of origin of domestication in that region).
This hypothesis was based on archeological findings and on the fact that domestication
of other species started in that area. In fact it is believed that the evolution
of our own spp. Homo sapiens started around that area. Is it a coincidence,
or a fact needed to be taken under consideration, due to this highly extreme
connection between the 2 creatures?
Hypothesis 2-domestication started 100,000 years ago.
A study done by Vila et al. (science magazine 276, 13, 1907):
Mitochondrial D.N.A control region sequences were analyzed from 162 wolves at
27 localities worldwide and from 140 domestic dogs representing 67 breeds.
These sequences supported the hypothesis that grey wolves were the ancestors
of dog, and that domestication started about 100,000 years ago. Repeated genetic
exchange between dog and wolf populations since, may have been an important
source of variation for artificial selection.(www.ncbi.nlm.nih.gov/entrez).
Hypothesis 3-domestication started in East Asia, 15,000 years ago.
An article published in science magazine (298, 5598) suggested that the origin
of dogs came from east Asia, around the area of China, about 15,000 years ago.
In a study done by Savolainen, Zhang, Luo, Lundeberg and Leither, mtDNA sequences
were examined from 654 domestic dogs, representing all major dog populations
worldwide. Their findings show that more than 95% of current dogs come from
3 female wolves, the so-called Eves of the dog world. A larger genetic variation
in East Asia than any other region, suggested that the domestication started
there.
Hypothesis 4- domestication started 12,000-14,000 years ago.
Leonard et al. examined mtDNA from 37 dogs deposited in archeological sites
in Mexico, Peru and Bolivia, and from Alaskan dogs buried before Europeans arrived.
These data were compared to sequences from 67 modern dog breeds, and from wolves
from 30 locations worldwide. Their findings conclude that ancient American and
Eurasian dogs share a common origin from the gray wolf, and that domestication
started 12,000-14,000 years ago when man colonized the new world. They further
concluded that the large diversity of mtDNA observed in dogs implies a large,
well mixed ancestral population of Eurasian dogs.
Conclusions:
From the data above, the ancestor of the dog is the wolf, and domestication
started sometime between 12,000 years and 100,000 years ago in the area of Asia.
The extremely close connection and quite amazing mutual understanding between
dog and man (a research done by Hare B. et al. showed that dogs understand human
facial signs better than our closest biological relative- the chimp!) (Science
magazine 298, 1613-1616) surely suggests that the 2 creatures go together for
a considerable amount of time.
If we take in consideration that Homo sapiens evolved around 150,000 years ago
(another estimation still under debate), I believe that the connection between
man and wolf started pretty soon after (a matter of a few thousand years)- if
for hunting cooperation, or even for friendship, that turned up to be one of
the best things that happened to mankind in it’s existence!
References:
www.enn.com/news/wire-stories.
www.ncbi.nlm.nih.gov/entrez.
www.nature.com.