Horses: Amazing Photos & Fun Facts Book For Kids Horses are considered as one of the oldest species of animals. The first horses that ever ran wild on Earth lived more than 40 million years ago. Since then, much has changed in the appearance of horses. Humans began taking care of wild horses more than 4,000 to 5,000 years ago. Until now, many children and adults take care of these animals. With 750 million horses living today, every kid aging 3 to 7 years old can have a horse for himself/herself. Horses are one of the most popular animals on the planet. They can be found in almost all countries around the world. Many story-books and TV shows also feature horses.