Health seems complicated. And in fact it is, if you are willing to see it that way. It can get immensely complex. If we view our health through the lens of our environment things start to make sense and intuitively become simper. Question like why meat is a cornerstone of our diets, why certain anatomical features are as they are, or why our sexuality plagues the modern concept of marriage start to make sense.
The book down below do an excellent job in compiling up the evidence found and putting it into the right context. Understanding health does not have to be complex, if we live in sync with the environments that shaped us it even becomes naturally simple. Our ancestors never needed to think about their surroundings as nature provided them with exactly the right stimuli, but with us nowadays playing the architects of those we run into the need to think actively about the engineering problems nature so gracefully solved.