BBC News, Jonathan
Amos, Science correspondent, 23 January 2013
Related
Stories
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| Wolves that coped best with cereals in their diet may be part of the story of domestication |
But this
annoying behaviour may have a more profound undercurrent than we realise,
according to scientists.
A new study
of dog genetics reveals numerous genes involved in starch metabolism, compared
with wolves.
It backs an
idea that some dogs emerged from wolves that were able to scavenge and digest
the food waste of early farmers, the team tells Nature journal.
No-one
knows precisely when or how our ancestors became so intimately connected with
dogs, but the archaeological evidence indicates it was many thousands of years
ago.
One
suggestion is that the modern mutt emerged from ancient hunter-gatherers' use
of wolves as hunting companions or guards.
But another
opinion holds that domestication started with wolves that stole our food
leftovers and eventually came to live permanently around humans as a result.
"This
second hypothesis says that when we settled down, and in conjunction with the
development of agriculture, we produced waste dumps around our settlements; and
suddenly there was this new food resource, a new niche, for wolves to make use
of, and the wolf that was best able to make use of it became the ancestor of
the dog," explained Erik Axelsson from Uppsala University.
"So,
we think our findings fit well with this theory that the dog evolved on the
waste dump," he told BBC News.
'Generic'
dog
Dr Axelsson
and colleagues examined the DNA of more than 50 modern dogs from breeds as
diverse as the cocker spaniel and the German shepherd. They then compared their
generic genetic information with those of 12 wolves taken from across the
world.
The
Swedish-US team scanned the DNA sequences of the two types of canid for regions
of major difference. These would be locations likely to contain genes important
in the rise of the domesticated dog.
Axelsson's
group identified 36 such regions, carrying a little over a hundred genes. The
analysis detected the presence of two major functional categories - genes
involved in brain development and starch metabolism.
In the case
of the latter, it seems dogs have many more genes that encode the enzymes
needed to break down starch, something that would have been advantageous in an
ancestor scavenging on the discarded wheat and other crop products of early
farmers.
 |
| Domestication may have forced dogs into a permanent state of puppyhood |
"When
we look at the wolf genome, we only see one copy of the gene [for the amylase
enzyme] on each chromosome. When we look at the dog genome, we see a range from
two to 15 copies; and on average a dog carries seven copies more than the wolf.
"That
means the dog is a lot more efficient at making use of the nutrition in starch
than the wolf."
As far as
the brain development genes are concerned, these probably reflect some of the
behavioural differences we now see in the two canids.
The dog is
a much more docile creature, the likely consequence of early humans
preferentially working with animals they found easier to tame.
"Previous
experiments have indicated that when you select for a reduction in
aggressiveness, you obviously get a tamer animal but you also get an animal
that retains juvenile characteristics much longer during development, sometimes
into adulthood," said Dr Axelsson.
This might
go some way to explaining the oft-repeated observation that dogs are
permanently stuck in a kind of puppyhood.
Open debate
The study
of the origin of dogs remains, in many ways, a puzzling field.
Fossil
evidence suggests some populations could have been around tens of thousands of
years ago, long before the emergence of agriculture. Some researchers have
tried to use the regular rate at which error patterns appear in dog DNA as a
kind clock to time their rise, but this has produced contradictory results.
One
confounding issue might be that domestication happened more than once.
Dr Carles
Vila, from the Conservation and Evolutionary Genetics Group at the Donana
Biological Station in Seville, Spain, said the debate was wide open.
"I
think that modern dogs derived from multiple wolf populations," he
observed.
"It
could be that dog domestication started once with some animals staying with
humans which were then regularly back-crossed with wolves and that could have
the same effect. But there could have been completely independent
domestications. What is clear is that the number of bone remains is very rare
more than 14,000 years ago."
Related Articles:
“… The dog
has a very faithful nature to those whom it considers it's family. Many times
the dog will energetically take negative energy from your energy field. Of
course if there is a lot of negative energy the dog can and will become ill,
and sometimes even cross due to the great amount of negative energy it has
"taken" from you. Many animals work on an energetic level,
particularly the domestic dog and cat.
Those animals who remain in their native state, what you would term wild animals, do evolve, yet at a slower rate. Their consciousness is not as developed, so their focus is on survival and caring for their young. ….”
Those animals who remain in their native state, what you would term wild animals, do evolve, yet at a slower rate. Their consciousness is not as developed, so their focus is on survival and caring for their young. ….”
"... Certain
breeds of what may be termed house cats and dogs, are indeed uniquely designed
derivations of the Starseed Felidae. They perform specific roles in assisting
humans. The 'house' versions of cats & domestic dogs are genetically
engineered from the Golden Age of Atlantis.
The genetic engineering was benevolently done by the Sirian - Pleiadean Alliance and is an extremely helpful action, as stated to assist humanity as they became more densely ingrained in the Earth-Plane.
Now, what you term as canine and feline are of the same source, both are derivations of the Starseed Felidae. Cats and dogs are different physical forms of the same source.The Felidae of Sirius A are a fully conscious crystalline being. They have melded into a group unity consciousness, yet still retain aspectual individual identities with the greater harmonic field. The Group Field chooses to assist humanity in your Universe and others.
Cats & Dogs
The genetic engineering was benevolently done by the Sirian - Pleiadean Alliance and is an extremely helpful action, as stated to assist humanity as they became more densely ingrained in the Earth-Plane.
Now, what you term as canine and feline are of the same source, both are derivations of the Starseed Felidae. Cats and dogs are different physical forms of the same source.The Felidae of Sirius A are a fully conscious crystalline being. They have melded into a group unity consciousness, yet still retain aspectual individual identities with the greater harmonic field. The Group Field chooses to assist humanity in your Universe and others.
Cats & Dogs
Both cats
and dogs in this derivation are serving as benevolent energy giving assistants
to humans, to their caretakers. Both have the capacity to meld their energy
fields with the human and are uniquely capable of becoming personality
fragments of their human caretakers. That is why certain of these can often
begin to display the physical characteristics of their 'owners', although this
particular aspect occurs more commonly with the canine.
The canine
exudes an extreme loyalty and unconditional love. A dedication that
energetically is received by the human, and can assist in many ways. The dogs (
and cats) become both companions , healers and protectors. The feline, the cat,
is much more in the ethereal (antimatter) realm in its conscious field. That is
why many past societies worshiped the Feline forms of Jaguar, Lion, Tiger and
Puma.
These
beings are extremely aware of thought forms of ethereal realms and offer a
stealth strength and protection. The house cat is capable of tremendous
protection for their caretakers from untoward thought forms and negative
energies. Certain breeds of dogs have this ability as well, but it is expressed
and enacted differently. ..."
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