During an earlier time of global warming horses got a lot smaller than this (specially bred) mini-horse.
When the Earth warms up, animals get smaller. That’s what happened 56 million years ago during another time of global warming. Temperatures rose roughly 10 degrees Fahrenheit, and scientists examining the fossils of horses from that time are seeing that to cope with the heat, they began to shrink in size.
Up to that time, horses were already quite small – just the size of a 12-pound dog. But as temperature rose, they shrank down to the size of an even smaller cat.
Then, as the climate cooled again, they began to grow bigger.
“Horses started out small, about the size of a miniature schnauzer,” said one of the researchers, Jonathan Bloch from the Florida Museum of Natural History. “What’s surprising is that after they first appeared, they became even smaller and then dramatically increased in size, and that exactly corresponds to the global warming event, followed by cooling.”
He said this tells us that temperature is what’s driving the body size evolution for these horses. The report is published in the journal Science.
Modern-day mammals and birds are generally smaller near the equator, probably because smaller size helps animals regulate their body temperatures in the heat.
What does that mean for global warming today? It’s too early to say, and changes in body size don’t happen overnight. (For the horses, it took thousands of years for any difference to be noticeable.) But if the current warming trend continues long enough, and we humans survive to tell the tale, a few thousand years from now, we may end up being just three feet tall.