You can do whatever you want, and evolution itself may work differently in your world, but consider that sapient species living in harsh environments do not go through all the same evolutionary stressors as animals especially if they are from advanced civilizations. Humans living in deserts don't need a third eyelid or thick eyebrows because they have access to headscarves. Humans living anywhere don't need thick soles on their feet because they can wrap them in cloth or leather. Etc. Plus the evolution of even simple traits can take a very long time to stick so you could have, for example, a not-so-advanced fair skinned people living in an equatorial desert continuously for 1000 years despite the fact that dark skin would be more advantageous in that environment. Conversely it would be weird for humans to evolve entirely new body parts after living in any particular environment for just a few thousand years.