Daily Mail via
Spluch.
Meet Thumbelina, the world's smallest horse. She's just 17 inches tall despite being an adult horse, 5 years old.
I want one!
She was born at an American horse farm that specializes in tiny horses; normally the tiny beasts are twice Thumbelina's size.
That means Thumbelina is not really a freak of nature. My high school biology teacher used the local miniature horse farm as an example, when explaining genetics. Part of the theory of evolution is that genetic mutations happen and the new changes are accepted or rejected over time, slowly leading to improvements and adaptation. The mini horse tells us that you don't necessarily need mutation to vastly change a species.
It was a good explanation, but I would have used dogs as an example. The teacup Chihuahua, the Great Dane, the English Bulldog and the Russian Wolfhound, all are the same species. We have bred them specifically for genetic variations, and created dogs that wildly vary, to the point where most of the variations would not even continue to exist without human intervention.