@jerlands,
Human beings are healthier now than we ever have been in the past 20,000 years of history. Humans are living longer. Fewer humans are starving. Whole diseases that were deadly in the past are now curable.
There is no evidence that gluten sensitivity has anything to do with pest control or hybrid crops. Probably we just didn't recognize it because people were dying of polio, dysentery and starvation before we developed modern agriculture and medicine.
I suspect that modern diets are far less dependent on wheat then earlier cultures, particularly in the Mediterranean. We can now go to the local supermarket and get food from avacado's to lychee nuts flown in from every part of the world. Back then, except for the very wealthy, people ate the one or two things that were available and in season.
Any claim that humans today are less healthy than humans in past centuries is demonstrably false.