Let's say humans moved to Mars and have lived there for millions of years. Mars is of now uninhabitable, though in this case some terraforming has happened. The poles have been nuked to release greenhouse gases and a prosthetic magnetic field has been created, and also an ozone layer. The hows are not important. So, Mars is warm enough for humans, actually quite a lot warmer than on Earth today, and a weak and spotty ozone layer protects from UV-radiation. But not as much as Earth. The UV radiation is that of Earth's equator, just amplified quite a bit. This is due to the low resources going into the project, as the move to Mars happened in a drastic time of war on Earth, meaning they couldn't spend much time perfecting the terraforming process and outcome.
Now that all those details are out of the way, this is the product of my research: I know these martians would be a little taller than the average earthling human. Their skin would also be coal black, along with their hair and their eyes, due to the amplified melanin production to protect against the UV-radiation. I also know they'd be just a little weaker, unless for some reason their diet was more protein filled than that of ours today. So, how else would these Martians be different? What more would the conditions on Mars change about the human body?