In Human Height, Max Roser says:
Human height is determined by a combination of genetics and environmental factors making it an active area of research in both the sciences and social sciences. Recent breakthroughs in sequencing the human genome have allowed identification of 697 genetic variants that influence the height of an individual.1 Although genetics plays an important role in understanding variation within a given population, human growth can be limited by poor childhood nutrition and illness. This makes height strongly correlated with living standards and hence a good proxy for them. Changes to heights over time and within countries paints a picture of economic development. One major advantage of using height as a proxy is the availability of data in the pre-statistical period.
Interesting. Genetics matters — but only in context of environment and ecology. Factors in nature will turn genes on or off, make them expressed or not, affect how they are expressed. (Look up, if you have not heard of it, epigenetics.)
Looks like before agriculture, we lived in an environment that allowed human health to be optimally expressed — not in every way, no, but in many ways. We need to learn what were the factors that allowed Homo sapiens to be so healthy, and incorporate them intelligently into our lives today.
That does not mean to destroy all knowledge, learning, technology, and civilization to “recreate” life hundreds of thousands of years ago. That would be as wrong as to ignore the evidence and the fact that humans millennia ago were healthier than most today.
We need to figure out what is biologically and ecologically appropriate, and how to do things to best promote human life and life in general — and not continue blithely doing what we feel like doing or doing what convention says or blindly worshiping chemistry and technology, i.e., doing what is irrational and illogical. Reason and logic, properly understood and properly used, are life-giving and life-promoting; they are inductive and integrated and value-oriented.