As an Uber driver, I get the chance to speak to a lot of people of all stripes, flavors, and demographics. I get to see people in every possible condition of health from fabulous to people that look like they are on their last leg with crutches, canes, and walkers.
Another one that is very telling is the demographics of the people that I take and pick up from dialysis and the amount of melanin is the most obvious distinguishing factor. The more melanin, the greater the need of dialysis. Melanin is a pigment found in the skin that occurs in animals, human or otherwise and is what makes eyes, skin, and hair appear darker. Research has found that those with greater levels of melanin have a greater level of protection from exposure to UV light blocking the processes by which skin cancer is manifested. Conversely, melanin, blocks or absorbs the UV light that is necessary for the creation of vitamin D within the skin which is not a problem for people with less skin pigmentation.