Being well versed in the art of B.S..... I believe that there is room for a little give and take in this argument, regarding our capacity to adapt to anti nutrients and such.
Naturally organisms wish to maintain homeostasis, so whenever environmental stability would allow, creatures will develop specialized diets so as to limit their exposures to mutigenic compounds. These mutigenic compounds that an organism is exposed to when consuming foods outside of their habitual range, will cause physical discomfort , sickness, and will trigger the beginning of mutagenesis which is the process by which adaptation is passed to the next generation.
Having adapted to a particular diet an organism becomes dependent on a limited variety of food stuffs, from which its own DNA has become accustom Organisms will instinctively avoid mutagenic compounds that may jeopardize their present sense of well being. The bitter taste or unpleasant taste warns one that there is something to be avoided. Only as a last resort, when the pains of hunger and the prospects of starvation become present, will an organism dare to ingest material that they would instinctively avoid during times of plenty.
Mutegenisis is often a result of environmental changes which force an organism to consume foodstuffs outside of its genetically adapted comfort zone. More often than not it is a matter of survival which drives the desperate and dieing to consume foods which would normally be avoided. The results of the process of ingesting foods that one isn't fully mutagenically adapted are highly unpredictable, and the genetic changes that result of this are passed down to the next generation. The process has been mislabeled in the past as "random mutation" and I believe the word Mutagenesis a is more accurate term. Its often a brutal process which leads to deformity and failures of subsequent generations, which are dealt with through the process of " natural selection". For those who survive, the transnational changes provide the means by which an organism can mutagenically adapt to a change in environment.
Through our evolutionary history we have had long periods of relative stability, followed by times of incredible and drastic change. There is no doubt that our dietary past has left its mark, and has lead us to be the most adaptable omnivore on the planet.
The New science of micro RNA shows us how the food we eat actually is assimilated into our DNA. Over time dietary changes will reprogram our genes in order to facilitate Adaption. All life springs forth from a single source, and the genetic material of all the organic matter we consume infuses with our own genetics and alters the expression of our own biological workings, in a synergistic way, that works toward maintaining a balance and harmony between an organism and the environment composed of other organisms. It would greatly benefit the progress of scientific understanding if these discoveries where more clearly understood by the mainstream.
This process of adaption to the intake of organic sustenance of genetically unfamiliar sources is often not very pleasant, and for animals to become adapted to the anti-nutrients, bio-toxins, and mutagens, contained in historically alien food stuff, there are negative consequences. The great plagues and scourges of our history are a testament to the painful process of adaption. Though, while many who attempted to survive off of foodstuffs they were ill adapted too, were wiped out and annihilated by natural selection..... there were those who were able to develop the genetic adaption necessary to survive on grain rich, cooked diets full of bio-toxins and anti-nutrients.
In digression, I am one who feels like there are many layers to the discussion, and though some segments of the human population have been able to adapt to significant amounts of anti-nutrient rich neolithic foodstuffs, that does not mean that these foods are optimal.
Even though some may have an adapted to handling these modern foods, these adaptions are so new that they have yet to work all the bugs out of the program. Also the environment is continuing to be polluted and degradated at a rate far beyond the capacity of any organisms capacity to adapt. It should be obvious to people on this forum that many people are still struggling to conform to these complex and artificially concocted changes to the human diet that began in Neolithic times, and have reach a level of out of control insanity within our present day.
For the people who are not suited to consuming the high levels of anti-nutrients, caramelized proteins, vegetable oils and refined carbohydrates which make up the base of the modern diet, there is a better way. The paleo diet can lead you back to more stable dietary default setting which remain hidden deep within in our genetic hard drives, awaiting the signal to reactivate.