QUALITALY_136

September/October 2023 X MAGAZINE our DNA to extend or save our lives, as an individual first and then as a species. Not that our DNA is gratuitously altruistic. After all, by saving our lives it saves itself. SO HOW DOES TASTE MANAGE TO BE A VALUABLE ALLY IN THIS STRUGGLE FOR SURVIVAL? The perception of bitterness is a defence mechanism that allows us to identify potentially toxic substances in food. Let us think of plants. Many toxic compounds processed by plants as a defence are bitter. The repulsion we often feel for bitter foods has precisely the function of avoiding the ingestion of potentially toxic compounds. The opposite is the evolutionary function of sweetness. Sweet are those foods that contain, for example, sugars and are generally high in calories. Think of our ancestors who inhabited the savannahs of the African continent and the difficulties they encountered in procuring food. The establishment of a mechanism of liking sweet and therefore preferring calorie-rich foods helped us at the origin of our species not to waste too much time on calorie-poor foord in a non-obesogenic environment, and to steer us towards certain calorie sources. OBESOGENIC? Which was in no way conducive to obesity. These adaptive mechanisms developed in an environment inherently poor in food and calories. In the African savannahs, there were no supermarkets open 24 hours a day where the necessary food could be conveniently obtained. In fact, procuring it was a struggle and costly. So there was an evolutionary need to reward in every way those behaviours that led to a safe intake of the calories needed for survival. Then we learned how to cultivate and breed, process crops and meat. We treasured this knowledge by passing it on from individual to individual and from generation to generation. We acquired the culture of knowing how to cultivate, how to breed, how to transform, evolving from being simple hunters, fishermen, gatherers. Today we have plenty of food. Sanitary control systems are so good that we hardly run the risk of buying and consuming food that is harmful to our health. Yet, although the paradigms of food procurement and nutrition have changed, we still prefer what is sweet and reject what is bitter. HOW DO WE EXPLAIN IT? In genetic and anatomical terms, biologically then, we have not changed much from our savannah-dwelling ancestors from whom we have inherited many adaptations. Culturally, on the other hand, we have evolved very much and very quickly. Biological and cultural evolution are radically different processes: one takes tens of thousands of years; the other proceeds at the speed of light. This has led to behaviours that were once adaptive turning out to be partly obsolete and out of step with the times: we do not like bitter foods and therefore avoid many vegetables that are bitter, but completely healthy; we still love sweet and fatty foods and consume more of them than we need because of an atavistic fear of not ingesting the right calories and we get fat. Obesity has dramatically increased, becoming in effect a global epidemic social disease. TASTE HAS OBJECTIVE CHARACTERISTICS, BUT THE REACTION TO THAT STIMULUS IS SUBJECTIVE. HOW DOES THIS CRITICISM WORK? At the level of chewing food, we have small individual differences, both anatomical and physiological, that lead to variations in the ability to ‘prepare’ food for the taste buds to receive the taste stimulation to be sent to the brain for integrated processing. Genetic variations associated with individual differences in taste perception are well known for bitter, sweet and umami. TAS2R38, for example, is a gene that regulates the taste response to a range of bitter compounds: depending on the structure of this gene, different degrees of perception of the intensity of the taste stimulus can occur for the same bitter compound and concentration. If a subject is genetically predisposed to a very intense perception of bitterness, he will tend not to like this food. He will tend to like it more if he has a low perception of the stimulus. SO WE ARE IN A SENSE DOOMED? Not in an absolute sense. Exposure to bitter foods through our diet actually generates a familiarisation process through which we can learn to like previously disliked bitter foods and make their consumption more palatable. The environmental variables of the physical, economic and socio-cultural context in which we live and eat count a great deal in the process of forming and establishing our preferences. Each individual, each family has its own eating habits. The foods and the frequency with which they are served vary, but so do the normative contexts in which foods are consumed. It is these environmental variables that characterise us in our