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In the world that I am building, I have four (major) races: Human, Elf, Orc, and Dwarf.
Humans are the run of the mill; average in physiology, psychology and magical ability. They can survive almost everywhere.
Elves are tall, thin, and significantly faster than any other race. Higher than average intelligence, but significantly weaker in magical ability. They don't survive very well in colder climates, but can.
Dwarves are short, stocky, but proportionate. Their muscles are denser than humans and elves, so they are stronger than average. They are not fast, but can easily outlast their opponent in battle. Their magical ability somewhere between a human's and elves, with elves being behind. They do not do well in warmer climates.
Orcs are thick, massive, and brutish. Their race is the strongest in physiology and magical ability, and lacking in psychology. Literally can survive anywhere.
The way the races' bodies are set up are basically the same.
The problem I am having though, is what's a plausible common ancestor to all these races? Since all these races are humanoid, and bipedal, would they still come from a monkey like common ancestor? Or would it be that millions of years ago, a human was their common ancestor?
Knowing a plausible answer to this would impact how the Orcs and elves of this world would view the other races around them.