An interesting essay in the New York Times today by Jo Robinson: "Breeding the Nutrition Out of Our Food". The theme is that plant domestication selected for certain traits that made our grains and vegetables more amenable to rapid calorie production, but these have often decreased the amounts of micronutrients in the resulting food products:
Studies published within the past 15 years show that much of our produce is relatively low in phytonutrients, which are the compounds with the potential to reduce the risk of four of our modern scourges: cancer, cardiovascular disease, diabetes and dementia. The loss of these beneficial nutrients did not begin 50 or 100 years ago, as many assume. Unwittingly, we have been stripping phytonutrients from our diet since we stopped foraging for wild plants some 10,000 years ago and became farmers.
These insights have been made possible by new technology that has allowed researchers to compare the phytonutrient content of wild plants with the produce in our supermarkets. The results are startling.
I think it's useful to keep in mind that the qualities of food that loom important for us now, in an age of rapid transcontinental refrigerated food transportation, are not the same qualities that mattered to the first agriculturalists. Five thousand years ago, people needed food products that could be stored through the lean season, that made harvesting the plants easier, and that resisted the insults of bad weather and pathogens. Robinson focuses attention on the developments of the last hundred years, in which some crop varieties have been selected for much higher sugar content, but the long history of domestication before these recent events has also shaped the taste and nutrient content of foods.
I also demur from the conclusion about the health of ancient people:
Were the people who foraged for these wild foods healthier than we are today? They did not live nearly as long as we do, but growing evidence suggests that they were much less likely to die from degenerative diseases, even the minority who lived 70 years and more. The primary cause of death for most adults, according to anthropologists, was injury and infections.
I wouldn't generalize on this point, which would be tricky to demonstrate given the evidence we have. My inclination is exactly the opposite of Robinson's implication here: the minority of hunter-gatherers who live to advanced ages are relatively healthy because the slightly less healthy ones at all life stages are more likely to be felled by infections and injury. This is the concept of "frailty" in life history theory, and is well demonstrated in some historical famines and epidemics. The people who are least healthy are least likely to survive. What we have today is an advanced ability to allow relatively unhealthy people to survive to advanced ages despite their health problems.
Still, I think the essay's bottom line is basically correct. More diversity of foods is better. Selecting foods as part of your diet that have come from a broader array of heirloom and wild varieties is one way to add to that diversity.