Did humans realize that animals could be useful and then domesticate them?

Presumably, this is how it happened. If you think about it, you can see a likely course of events. Early humans were nomads who followed herds of animals that provided them with meat, tools and skins. Eventually they may have realised that by blocking their paths or running to scare them, they could alter the path the animals took each year, such as driving them to where they knew they would find a good campsite. Eventually this would have extended to barring off many exits to keep the animals in one place for longer. It's easy to see how these barriers could have become a fence to contain the herd. Domestication would have followed as a logical step because animals that are tame and trust humans are less dangerous and easier to manage. Non-food domestic animals were probably domesticated in a different way. When humans started building permanent settlements due to the development of grain farming and domestication of herd animals, rodents were drawn to the large stores of grain that were set aside for winter. It is understandable that a child, finding a nest of small, wriggling pinkies, may have decided to keep one as a pet. Cats were drawn by the rodents. It is unsure how they may have been domesticated, but since cats do not hunt with humans it is likely that they were domesticated to be pets and not partners. Cats are naturally affectionate, particularly if they have known human contact since they were kittens, and it is easier to imagine each successive generation of barn cats becoming more tame. It is even easier to understand if you consider that humans would have been grateful to the cats for killing the rodents that were damaging their grain stores. Dogs were domesticated much earlier, in some parts of the world well before large herd food animals. Dogs are intelligent and equipped to hunt, but do not require much food. They are savage and capable of protecting the nomadic human, and also of providing him with food. In lean times, wolves would hang around the human camps, hoping for scraps of meat, or even human faeces which a dog can still obtain nutrition from if it was desperate. Obviously the human would not care if the dog ate discarded bones or human waste. Again, it is easy to imagine each successive generation of wolves becoming more used to humans, venturing closer, perhaps being touched by an inquisitive hunter or his child, maybe nuzzling a woman as she cooked dinner hoping for scraps. This process would have been hastened if the dog ancestors were deliberately captured when young because the humans saw their use as hunters. Horses were first domesticated as food, and nobody knows for sure when humans started riding. There are skeletons thousands of years old that indicate bevelling on the molars, caused by a piece of rope passed through the diastema - the earliest known bit. Humans may have ridden a horse earlier than this, either for the sheer exhilaration without trying to control it, or controlling it only with their feet and hands. The saddle was a late development, and the stirrup came even later, not invented until the Mongolian army of Genghis Khan. I'm not sure when humans realised that horses were suitable for hauling loads, but oxen were mainly used for farm work for a long time because they were stronger until draught breeds were developed.