Man's best friend...

The species name is Canis familiaris. It refers to our oldest companion and friend, the dog. Like us, it is classified as a eukaryote, having its genetic material stored in the nucleus of the cell. The genomes (full collection of genetic material) of two dogs, a Poodle named Shadow and a Boxer named Tasha, were sequenced in 2003 and 2004.

For genome scientists the dog is interesting because they get the same diseases we do, including cancer, heart disease and epilepsy. Dogs are also striking in their remarkable diversity in appearance and temperament. There are very small and very large ones, gentle and exceptionally vicious ones. We have of course bred them to be like that.

Today’s dog is a direct descendent of the most successful wolf ever, Canis lupus. About 150,000 years ago, this breed of wolf inhabited, even dominated, most of Eurasia and North America. At that time, small populations of archaic Neanderthals lived in today’s Western Europe and even smaller populations of homo erectus in Southeast Asia.

Modern humans – you and I – evolved in Africa and are about 150,000 years old. The evidence is pretty strong that dogs were first domesticated from Canis lupus about 135,000 years ago. Humans and wolves have much in common. They are cooperative hunters and have extended family structures.

Back in time, one can imagine how wolves, bred to be tame, would provide an enormous advantage to humans who domesticated them. Their strength, stamina and cooperative hunting skills, vastly superior sense of smell, made them astonishing hunting partners.

With their sight and sleep cycle, dogs happen to be much more alert at night. Smell and sight combined to sense predators well before we could and for this reason they guard our homes better than any burglar alarm in modern times where we, sadly and pathetically, require protection against our fellow human beings.

A history of close bonding within the wolf pack and, with their wonderfully calibrated social intelligence, allowed domesticated wolves to become part of the human extended family. We all know and take for granted how easily dogs bond with us. We have been together with them over a long time.

Humans brought food for their pups. With regular feeding and human sources of protection, our support allowed dogs to have two litters of pups per year, instead of the single litter that the dog’s ancestor lupus’ other descendent, the modern wolf, has. They - and us - became reproductively highly successful as a result.

The evidence is also strong that initial domestication of wolf came about with cub raising. John Allman writes: ‘Humans, like the dominant pair in the wolf pack, controlled access to the killed prey. The essential act in domestication was maintaining dominance over the wolf cubs once they had matured, the rest was part of their natural behaviour.’ (Evolving Brains, New York, Scientific American Library, p.208). That is why dogs still lick human male faces, to ask submissively, for food.

Like other life forms, wolves were diverse in appearance, stature, and temperament. Humans proceeded to enhance their characteristics by having like breed with like. Sometimes it is simply to accentuate anatomical aesthetics, such as Pekinese dogs having been bred to resemble infants with their reduced jaws.

Sometimes selective breeding has been used to change behaviour. It works developmentally, Allman writes: ‘The predatory act of wolves involves a series of distinct behaviours – stalking, chasing, grab-biting, and kill-biting – that are required in progressive stages as wolves mature. Dog breeders selected against some of these behaviours.’ (p.207).

In this way, Border Collies have been bred to stalk and chase but do not grab or kill sheep. Sheep-guarding dogs like Komondors have been selectively bred to eliminate all forms of predatory aggression towards sheep. There are dogs that help with hunting but do not kill and then there are of course the killer dogs themselves.

When it comes to stature, the same homeobox genes that determine our shape, size, skeletal body plan and architectural points of limb attachment dogs have too. The DNA elements are the same. The overall design is obviously different.

Our friend the dog used its keen senses to locate, grab-bite, run down and seize prey. When our ancestors gathered around the campfire, there was the dog part of the family. When we were cold, they also kept us warm. Today the dog is our loyal companion. And how do we treat our greatest friend today?