A horses legs have changed over time to accommodate a new type of environment and lifestyle for the horse. The first horses began as a fox sized browser that ate leaves and lived in a forest where multiple toes was an advantage for a prey animal. As the environment changed and gave way to grasslands the horse began to loose it's extra toes and become a grazer. It's legs lengthened to provided better speed and height in the tall grasses and a single toe was all they needed to survive.
It has become a lot more humane. In very old movies to make horses fall a line would be placed in front of the animal's legs causing it to trip and fall. These days computer generated graphics are used for these sceans.
The chestnuts on a horses legs actually were, a long time ago, a "toe" so to speak. Of course, evolution has changed that all, and now all it is is a oval-ish thing on a horses leg!
Horses were used for transportation, herding cattle, pulling barges, pulling plows and other work. Today they are pets for the rich to ride and race.
how the anemometer changed over time
how the anemometer changed over time
Because they were millons of year of go they were the same size as the dogs but now it has all changed
The laws of physics have not changed over time. Our understanding of them has changed over time.
Horses only have four legs... so if you meant to ask "why do horses have four legs" then the answer would be that four legs fit the horses needs the most, for example six legs would make it hard to turn and would make the horse too long. But in the same way two legs wouldn't be enough because the horse would have to stand on its hind legs and since it wasn't made for two legs the horse wouldn't be able to stand up and would fall over.
how has coal mining changed over time
People changed over time by growing up.
Your legs, boats/ships and horses !
no they have changed over time. no they have changed over time.