I have spent a lot of years reversing symptoms of my genetic disorder as well as reversing issues in my special needs sons. Altering my diet is a very big part of that. Humans have been around a long time. Some of the issues my sons and I have are relatively "new." I spend a lot of time wondering how much that is a product of "new" environments rather than "new" biological issues within humans themselves, if that makes any sense.

My dad was old enough to be my grandfather. He grew up on a farm, without the constant noise of modern life. When I lived with my parents during my divorce, I realized my oldest son had many things in common with my father. I had never before realized. The sensitivity to noise that is viewed as pathological and worthy of labeling as ASD or as having sensory issues is something both my parents had. They were just old, grew up in a different era, and expected the house to be kept quiet. No on acted like their preferences were a "special need" requiring a label...etc.

Sorry if that is not very clear. I wonder a lot at how much our modern "ills" are really a product of our modern lives -- of environments that did not exist until recently but which we view as something "normal" that "everyone" should be capable of coping with. It isn't looking for confirmation bias. It is wondering how much bias exists in some of the assumptions we make in how we frame certain kinds of problems.

This is why I caution you against confirmation bias. The modern life also allows plenty of people who weren't previously viable to achieve adulthood. I'm not talking about Spartan exposure of sick infants (which is an outlier), but that people with sensitive constitutions were more easily taken young by disease in the first place. The high infant mortality of the past is a significant example.