Back in the caveman days it was the strongest who survived.
You had to stay healthy and strong no matter what or you were gone.
No medicine, good shelter or steady food. Those people were hearty. They just lived off the land and the best ones got to live. If you did that to people now, we would not do so hot. I would be picked off within a week. For one, I am totally used to having climate control. I have zone control for my house. Every room is set to a unique temperature program. I get AC when I work out, heating when I sleep and quality cooling when I have dinner. I even control the humidity levels in those spaces. However, the main issue for me in the wild would be the air quality. I have a dehumidifier to work with my air conditioner. I have a humidifier for my heating system. I have an air purification system and UV lights installed in the HVAC. Any little air quality device you can come up with, I have it. I want my indoor air quality to have the right amount of moisture and be clean. That is because my skin dries out or breaks out easily. I also can get sick from dusty air conditions. Can you imagine me as a caveman? I heard the outdoor air quality is actually cleaner than inside. But what about how dry it gets in the winter and moist in the summer? I would be dead or ready to kill myself without my IAQ equipment.