One day, Phillip Buster had an idea. Not many people lived on the Earth yet, and his tribe relied on hunting and gathering to survive. Wolves were good at hunting, he mused. Wouldn't it be interesting to have them work for him?
He managed to get some wolves into possession and carefully put them together to have cubs. Neither Jeans nor genes were known at his time, but Phillip did know that children looked different from their parents and also exhibited different personalities. Maybe the wolves would eventually have an offspring that his tribe could use.
Genes are the blueprints of a being, how it is shaped, how it grows and in many ways even how it behaves. But these blueprints don't copy perfectly. There are small alterations, changes, and so a new animal would always be slightly different from the animals that came before. Perhaps it would have the tendency to be more playful, or it may be better at sniffing, or it may be friendlier towards other beings, such as Phillip himself.
Over the years, Phillip experimented with many generations of wolves. He would raise them and observe carefully, which tendencies they exhibited. Then he would select the ones he judged useful, put the animals together again to get a new generation of cubs. As time went on, Phillip's work bore fruit and indeed, the first wolves began to work with humans, helping the hunters to find and kill prey.
Phillip's work was so useful and revolutionary to the human condition, it was carried forward by many others, taught and applied in hundreds of ways. Thousands of years passed. Now, the landscape of the world had changed; humans were more abundant and were living in castles. And there were birds flying through the skies that carried messages from men around with them, finding their goals with pinpoint accuracy. Wolves had changed into many forms and were now referred to as dogs. Many different kinds of cattle now lived on the land that had never before existed. They produced milk that, for the first time, humans could drink without being sick.
Eventually, humans entered a new age and largely began to forget the ancient knowledge that had gotten them so far.
Dogs are man's best friend, simply because we made them that way. Dogs are a technology - perhaps the most sophisticated technology ever conceived and developed by man. As is all cattle, carrier pigeons, most pets and even plants. They were all sculpted from ancestral beings by selective breeding.
So you may not have realized it, but your pet is a technology, and it was made for you.
PS: Cats were bred for Youtube.
Disclaimer: The real story of selective breeding began over 40,000 years ago, so there are no records of it. My story here is a freely invented short version of it to explain it all in a simple way. It shows how we humans have altered the world to make it suitable to our needs. We have altered many types of plants, cattle and farm animals in general, and we created animals to work for us. Interestingly, it means we have used biological evolution for millenia before it was explained scientifically.