Furgone Conclusion

I was listening to another Sleepy Time History podcast. It kept putting me to sleep, which was, of course, at least part of the intention. It was interesting as most of their podcasts are: How Humans Lost Their Fur. I wanted to know more, and  while I do intend to get back to the 2+ hour podcast, I wanted to know the essentials in summary form, so I hit the internet for just the very basics. This is my summary.

Scientists have deduced that we lost our fur between 1.2 and 2 million years ago. I know that is almost a million year difference between the two dates, but there was no observer available to take notes. From what I can gather, I think the consensus is that 1.2 is the likeliest time frame for the process to have been completed, but it may very well have begun earlier.

They ascertain this by trying to trace the MC1R gene, which is the gene that governs skin pigmentation. No, I don't know how they trace this.

When our ancestors had fur, which they did by the way, their skin underneath the fur would have been light. When they began to lose their fur, it was important that their skin would then become dark as a defense against the strong African sun, under which humanity began.

Under those conditions, dark skin was advantageous to human health and well-being, so natural selection over scads of time favoured darker skinned individuals to be healthier and more successful in life and, therefore, in reproducing.

It happened because of climate change. There was a time way way back when the climate became drier, so the vegetations also changed to more grassland and less tropical forest. When the forests shrank, the ancestors of those who became humans, would have found it advantageous to stand up and walk more. Walking upright is much superior to ambulating on all fours over distances. An upright position would also better allow them to scan for dangerous predators. It became an evolutionary advantage to walk upright, so that is what occurred over thousands of generations  

Our furriness became a hindrance because fur was an insulator in the African heat, humans began to shed their fur. However, with less insulation they also began to require another way to deal with heat. Glands developed to cause early humans to sweat, and the subsequent evaporation helped to dissipate the bodily heat. Concomitantly, humans also developed dark skin to help protect from the harsh rays.

That is how exploring the gene that controls skin colour helped scientists to determine when humans also lost their fur, for the loss of fur and the development of dark skin occurred in connection with each other.

That seems to be the bare bones of the prevailing theory as best as I can understand it.

Almost ironically, about a million years later, when a group of homo sapiens left Africa for Europe, dark skin became a disadvantage in the long winters of the ice age in Europe. People no longer required protection from the harsh African sun but rather needed to absorb all of the vitamin D  that they could from the weaker northern sun. Light skin then became an evolutionary advantage that natural selection favoured in more northerly regions.