However, I digress and want to focus on fitness which is defined by Dawkins as:"fitness has the special technical meaning of reproductive success" which means that fitness is necessarily related to reproduction. So to be fit means that you have good reproductive chances based on a given community- even if Dawkins chooses not to use the term fitness for most of the book. SO fitness in this sense means that we are healthy and capable of reproducing. However history is going to change what that means since for primitive humans what was necessary for reproduction will be very different from today. In primitive times it may have meant having the strength to kill competitors for a selected mate (I have no idea how cave people 'courted'?) BUT today it is much more about displaying physical beauty, and emotional and financial strength in order to show potential 'mates' that you would be a great choice to reproduce with. I guess that is why the 'fitness industry' is in many ways very superficial and based on pictures and videos and poses and all kinds of surface level stuff. Perhaps even more ironic is the fact that people in 'stage shape' often are not in a biological state that is even capable of reproducing at that time. When men use testosterone it can inhibit sperm production and many women lose their periods with harsh diets and androgenic drugs. So the term "fitness" (like many words as philosophers like to point out) is a tricky topic to pin down precisely.