Showing posts with label dog. Show all posts
Showing posts with label dog. Show all posts

Monday, August 08, 2011

The role of dogs in Human evolution


This week-end following the conversations we were having about Charles Darwin and the Origin of Species, Me and my son went to visit the Natural History Museum, Science Museum and Botanical Garden of Lisbon.

Lisbon Natural History Museum

On this visit we reflect on various aspects of the creation of the solar system, the emergence of life on Earth, evolution to dinosaurs (a subject that always fascinates children)

dinosaurs on Lisbon Natural History Museum

mass extinction of dinosaurs, evolution of mammals, and of course human evolution and the role of man's best friend, the dog in our evolution.

In our days it is believed that wasn't man who approached the wolf, but the wolves that followed the human groups to take advantage of the debris produced and often not consumed.


wolf

As the proximity of the two species were kept, the more likely situation is that the wolves became more docile and trusting, thus ignoring, the basic instincts. Animals that remained with the human groups, had more success in finding food, and therefore to reproduce and keep their young.

From the step to approach human beings and the first adoption that challenged the laws of the natural world, where humans and wolves competed as predators, we can only guess what happened.

wolf in a human group

With the domestication and adoption of wolves within the human group it is believed to have formed a symbiotic relationship where the Wolf received food, shelter and care from humans, and humans received protection and companionship, which evolves into a mutual aid in the hunt and later in other activities such as herding.

The man really helped in domestication by selecting the most pleasing docile animals and eliminating those with wild characteristics.
The Wolf, is thought to have contributed to man evolution by eliminating the man's need to develop physical senses, like smell to hunt. Also the use of Wolf, or probably at this point we can designate as dog , as a guard and herder, have actually contributed to the domestication of livestock, that in addition to sedentary agriculture, eliminate our physical characteristics required for hunting and fighting.

cave painting of a man with a dog

Archaeology has placed the earliest known domestication at potentially 30,000 BC in Belgium, and with certainty at 7,000 BC.
But it seems that Wolf domestication is older than the archaeological record so far found.

As the human migrated around the world, their dogs migrated with them. Changes to agricultural and urban areas have led to new selections and specializations, such as search and delivery of items, saving people, police dogs, etc. With the new selection was a new specialization of different types of dogs that best suited human needs.

immigrants with their dogs

Kennel clubs appeared in the middle of the 19th century as a way to regulate the various breeds, that already existed and were used in competitions.

one of the first dog show

Today these Kennel Clubs defines the dog breeds standard, which everyone recognizes.

Wolves, ancestors of our dogs have been since the Middle Ages, targeted has demons and systematically exterminated, witch almost led to the disappearance of these magnificent animals.

Let us pray that the future has room for a new harmony between man and wolf.

comparison of a wolf and dog paw

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Tuesday, August 02, 2011

The prehistoric dog



Charles Darwin
Not long ago I caught a documentary on BBC about our friend Charles Darwin and his famous theory The Origin of Species.

What is now regarded as obvious at the time gave rise much controversy and disbelief.

But now reflecting on the origin of species, I wonder ... "and our canine friends, how is the tree of evolution?



Ok, doing a little web research and photo summary, I found the following theory of evolution:

Mammals evolution tree:

Mammals evolution tree

1) The directly ancestral to all later canids is Hesperocyon

Hesperocyon

(about 40 to 35 million years ago)


2)Immediately follows the Leptocyon, considered a cousin.

Leptocyon

(about 40 to 35 million years ago)


3) Descending immediate from Leptocyon comes Eucyon

Eucyon

(about 6 million years ago)


It is believed that the first dogs are descendants of Eucyon therefore deserves a comparison with the wolf.

Eucyon
Eucyon

4) One of the first wolves is believed to have lived and competed directly with the large cave lions and saber tooth tigers, and it is called Dire Wolf

Dire Wolf

(about 2 to 10 million years ago)


5) The oldest dog skull discovered to date is from Goyet Cave, Belgium with 31,700 years old.
They are clearly different from wolves and is thought to be a transition from wolf to dog.

prehistoric dog fossil

In the end, only a theory of evolution from the wolf (Canis lupus) to the dog (Canis lupus familiaris) can be imagined.

dog evolution


Multiple and Ancient Origins of the Domestic Dog

Mitochondrial DNA control region sequences were analyzed from 162 wolves at 27 localities worldwide and from 140 domestic dogs representing 67 breeds. Sequences from both dogs and wolves showed considerable diversity and supported the hypothesis that wolves were the ancestors of dogs. Most dog sequences belonged to a divergent monophyletic clade sharing no sequences with wolves. The sequence divergence within this clade suggested that dogs originated more than 100,000 years before the present. Associations of dog haplotypes with other wolf lineages indicated episodes of admixture between wolves and dogs. Repeated genetic exchange between dog and wolf populations may have been an important source of variation for artificial selection.

ref: http://www.sciencemag.org/content/276/5319/1687.abstract?maxtoshow=&HITS=10&hits=10&RESULTFORMAT=&fulltext=vila&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT

Canid phylogeny tree

Canid phylogeny tree

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