: If caloric restriction in mamals works be changing cellular activity into a survive and protect mode, potentially increasing lifespans, why didn’t our prehistoric ancestors with low caloric budgets not live long?

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: If caloric restriction in mamals works be changing cellular activity into a survive and protect mode, potentially increasing lifespans, why didn’t our prehistoric ancestors with low caloric budgets not live long?

In: Biology
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Our ancestors lived in a hostile environment where they were preyed upon by carnivorous animals, had no access to medicine, and limited access to clean water. Surviving to reproductive age was the real accomplishment in furthering the species.

Caloric restriction alone doesn’t cause an animal to live longer. Although a slow metabolism can allow an organism go live longer there’s a lot more factors in play.

It’s hard to live long when a scratch can cause you to die a terrible death. Or a caloric restriction goes on for so long that you die. Or a predator eats you. Or a competing male kills you. Or you die in childbirth.

They had other issues shortening their lifespans like disease and injury. If they didn’t die from something like that, they could actually live a lot longer than we think of when we think of stereotypical cavemen. But there were a lot more dangers and a lot fewer safety nets and cellular efficiency doesn’t help with those things

I don’t think it has as much to do with calorie intake as it is to do with modern science and environmental factors. If they got so much as a cut on their finger, bacteria could enter and infect them very easily. Plus add the fact that they used to hunt animals for food, play with fire and not wear much clothing.

Bit of a digression here, but there are actually a lot of myths surrounding early, hunter-gatherer era humans.

For one, they largely had superior diets to modern humans. Roaming to hunt and gather resulted in a diverse range of meats, fruits, berries etc. Of course it wasn’t always stable, a poor hunting season for example could result in a famine.

Settling to make farms not only locked us to one particular region, but changed our diets to be dependant on staple foods like grains or rice. That’s not even to mention the last few decades moving to more processed diets.

Evidence also suggests Hunter gatherers to be more intelligent than modern humans. Being more or less self-sufficient, a hunter-gatherer would need very thorough knowledge and skill across a wide array of things to be, such as knowing how to hunt, prepare an animal, build a shelter, basic wound treatment, knowledge of plants, building fire, cooking meals, social interactions, delivering babies etc.

By comparison, modern humans have most of our needs met by other humans i.e.: someone else built our house, stocked our food, built our towns, looks after your injuries, fixes your car etc.

Modern humans can get away with being pretty unintelligent and unhealthy and still survive to reproduce without much problem.