Oh, and I forgot to add that pegasus wings aren’t really wings, but flaps of muscled flesh with feather-like structures to aid in flight. The ponies also evolved shorter snouts, softer fur, an omnivorous diet and some evolved horns.

I have a theory that the whole thing started when humans combined genetic engineering, nanotechnology and robotics to create a monster used to fight a war. The creature was dubbed ‘Discord’. Due to the nanotechnology, it was able to control weather, replicate matter, etc. It quickly rebelled and wiped out mankind. For millions of years, Earth was shrouded in constant chaos. After a while, a species of equine evolved sapience and civilization. Eventually, 2 individuals rose up against Discord and caused every cell in his body to fossilize. These individuals would become Celestia and Luna.

I headcannoned this a long time ago.

Human’s ascended and left the planet for the stars.

My thoughts exactly.
 
In the cheerful brightness of the far future, there is only pony.

The answer to everything is Diamond Dogs. DD’s were once the dominant race and much more civilised. But Discord found trolling cute things to be far funnier, so threw them aside. And the princesses, naturally, had no reason to restore the old status quo.

@ Putinforged
 
My headcanon is that Equestria is on the other side of the Earth, while Ooo is on the other.
 
Tee-hee.

Exhibit C: In Hearth’s Warming Eve, Pinkie explicitly states that they are on Earth.

“I wish Discord never even ever existed!”