The first wolf cub to be domesticated?
It is probably universally agreed today that the domestic dog’s wild ancestor is the Asiatic wolf. They lived in the warmer parts of the planet and their build is similar to that of the feral dogs of today. It is possible that some people imagine the wild dog’s ancestor to be a large, thick-coated beast of a wolf living in Russia, Scandinavia and Canada. But Dr Desmond Morris says that it is highly unlikely that these variants of the wolf were the ancestors because they are simply are two large. Another good point that Dr Desmond Morris makes is that the social lifestyle of the wolf was very similar to that of humans at the time that they were domesticated by humans.

Eurasian wolf. Collage: PoC.
They have “an impressive social organisation” like humans. It required restraint and a degree of altruism to use my words. There was cooperation on the hunt and defence of the group. Wolves in the pack other than the parents of a cub assisted in the feeding of young offspring. There was little fighting within each social group. This similarity in the lifestyles of wolves and early humans probably led to humans warming to the character of wolves. There are other similarities such as living in groups, having a home base as a centre of their territory, employing similar hunting tactics such as encircling prey, having male-female attachments and complex body signals including body language, postures and facial expressions.
Dr Desmond Morris suggests that humans and wolves competed and possibly the first domestic dog on the planet might have been a young wolf cub which had been picked up by a human and taken back to his settlement. Perhaps the man took the cub back to eat but before doing so allowed the him/her to wander around. The human infants in the group played with this young wolf cub and his parents decided to let the boy keep the him as a companion.
And so this little wolf gradually became socialised. And in becoming socialised the wolf cub became a domesticated dog. The cub developed into an animal which regarded a human as the leader of the [human] pack. The cub became part of the pack. Early domestic dogs became guard dogs raising the alarm and therefore they were useful to the human group. They might have tagged along on hunting sessions.
Early humans found that these first domestic dogs were useful. Eventually domestic dogs developed into guard dogs as that was probably the most useful specialism for dogs at that time. And today, their primary role is one of a companion although in many developing countries the domestic dog’s role is still that of security for the owner.