Is it because they keep on eating more and more food, while at the same time leading a very sedentary lifestyle and they do not ever exercise at all/ have any regular strenuous physical activities to keep themselves in good physically fit shape?
Just do it - Nike.
Time is simply how we live our lives-Craig Sager
Metabolism slows, older age is the age for the possibility of health problems, which can deter them from exercise.... That's only two examples, and that's only because I need more coffee.
The theory of evolution, like the theory of gravity, is a scientific fact. NDT