The show is about how we all started in Africa and migrated north then one group heads west and another group goes east. We lightened up the further north we went to be able to get the most amount of Vit D with shorter days I guess. But then how do you explain why the Inuit were darker in hair and skin and eyes?
Another point is when you are so far north it is very cold and you are bundled up and very little skin is open to the sun. So someplace along the way the lighter pigmented tribes survived better up north because they could now take in more Vitamin D through their skin while others with dark pigments further south could take in vitamin D much better and to screen out too much light. If our genetics could change for Vitamin D, then what else changed to adapt? Does one diet really fit all genetic differences?
I am of Scandinavian decent and have always been on the heavy side and docs would look at my stats and shake their head like they didn't understand why my heart rate was low, blood pressure low, cholesterol was good, no thyroid issues. They would try to find a reason to tell my why I should take off weight but the numbers were good. I wonder if I am designed to be more insulated than others for extreme cold and to survive long harsh cold spells/winters like a bear does.
Maybe down the road they will take a blood test of folks and new babies and from the genetic info they will be able to prescribe the optimum diet for you specifically based on your immune system and the way you process nutrients. Maybe they will be able to create a diet that changes during the different stages of your life that is tailored to your genetics. One size fits all never has worked for me in so many ways.