Virtually all the ethnicities that evolved on planet Earth are represented throughout the Olympian Galaxy, but people are typically more associated with their planet of origin that with their race; most humans consider themselves to be part of the same species, with Myridians being an exception due to genetic engineering. The last common ancestor of all humans in the galaxy is thought to have lived on Earth between 600,000 and 1 million year ago. Most humans outside of Earth are born without an appendix.
Some humans have much deeper physical differences: Scarab had a second gallbladder, unusually high bone density and a vestigial nictitating membrane, also known as a third eyelid, though this may have been the result of genetic engineering.
Humans are genetically compatible with Myridians and Gods. It's unknown of they are compatible with Demons, since intercourse between the two species is considered impossible due to anatomical differences. Humans can activate Drylon technology, but its use is highly deleterious to the nervous system.
Humans are an extremely young race compared to Gods, Demons and Lar, having developed their first society hundreds of thousands years ago instead of billions.
Today humans make up the vast majority of the population of the Olympian Galaxy. While most are under the rule of the Greek Gods, some planets are self-governed and/or isolated from the rest of the galaxy, like Earth itself.