According to scientists, humans living up to a ripe old age of 70+ is abnormal in the natural order. Many wild animals die of a parasitic infections long before they reach old age. The viruses, bacteria, fungus and even parasitic insects take their toll on them and they die. Cancer is almost unheard of.
Working backwards to humans in the Stone Age long before medicine or any sanitary living condition existed, a life expectancy of 37 years is expected. Females by that age would have born 3 children. Usually in succession. She would most likely be holding the hand of a child, carrying one with one arm and pregnant with the next. After this child, she will most likely die. Males are nothing but a cheap source of sperm.
Nature only cares about whether you reproduced passing your genes on. Once you did that, your job is done and Nature just disposes of you through disease or predators.
Things have changed a lot since then. We have advanced technologically and fight Mother Nature refusing to accept her BS. We improved living conditions, got medical to help us and even have the power to repair some body parts. The result is a longer lifespan with new problems the Stone Age man didn't encounter. Cancer, arthritis, failing vision and all those geriatric problems. Our biological over-engineering has begun to show itself which wasn't tested before.
In conclusion, if anyone wants you to live life the way it was hunting animals, gathering nuts and berries and foregoing all the living conveniences we got, tell them the truth that Mother Nature actually wants them dead when they 37.