Describe and evaluate the evolutionary theory of food preferences

According to an evolutionary approach current human behaviour can be understood in terms of how it may have been adaptive in our ancestral past. Evolutionary theorists are concerned with behaviour which is adaptive and having survival value, these researchers look for ultimate explanations. Current behaviours may be maladaptive and dysfunctional but can be understood as having been adaptive and functional in some way. To undertake this type of analysis they draw on the theory of natural selection and suggest that all species including humans, evolve through a process of natural selection and that only those characteristics that confer advantage or at least do not confer disadvantage survive as the species evolve. This is an interactionist approach, as an individual’s genetic predisposition is assumed to interact with their environment.

In terms of eating behaviour, an evolutionary psychologist is interested in the following questions: “Are there innate preferences for certain foods?”, “How would these preferences have been adaptive in the past?” and “How do these preferences function now?”

Early research by Davis investigated the eating behaviour of infants and young children. Davis observed the kinds of choice children living in a paediatric unit made in relation to their diet. Based on her data, Davis concluded that young children have an innate, regulatory mechanism and are able to select a healthy diet. However she emphasized that they could only do this if healthy food was available and suggested that the children’s food preferences changed over time and ere modified by experience.

Subsequent research has provided further support for some form of innate regulatory mechanisms. For example, there is consistent evidence that newborn babies demonstrate innate food preferences. Using facial expressions and sucking behaviour as an index of preference, babies have been shown to prefer sweet tasting substances and to reject bitter tastes. There is also some evidence for an innate preference for salt, based on animal research, although this has been controversial together, these studies suggest that some food preferences are innate. Beauchamp and Moran (1982) reported however that six month old babies who were accustomed to drinking sweetened water drank more sweetened water than those babies who were not. So although innate food preferences may exist, these may be modified very quickly by learning and familiarity.

Our early human ancestors lived in hunter-gatherer communities in which the men were responsible for hunting and the women were responsible for gathering. Their diets consisted mainly of fruits, berries, vegetables and some meat. Our innate food preferences can be explained in different forms. An innate preference for sweet foods would have encouraged people to eat fruit with its natural fructose content. Sweet foods in nature provide important calories which are needed for energy. Natural avoidance of bitter foods would have helped to protect people from eating food that was poisonous. This would also have been helped by neophobia. A preference for salt is less easy to explain, although we do know that salt is essential for the sodium balance in our bodies. Sheep manage their sodium levels by licking naturally occurring minerals that contain salt because grass has very low sodium content. Human beings on the other hand have very little need for additional salt, particularly if they eat meat. The innate preference for salt may therefore have originally functioned by encouraging people to eat meat.

In our ancestral past the main challenge facing people would have been avoiding malnutrition by eating enough food to support a physically active lifestyle. Our innate food preferences may have helped us to survive. However for much of the modern world, food is no longer scarce and our lives are no longer as physically active. Nowadays a preference for sweet foods may no longer encourage a person to eat berries, but rather to eat highly calorific, energy-dense foods, such as chocolate bars. Furthermore a preference for salty foods may facilitate the consumption of high-fat foods flavoured with salt, such as chips and processed foods.

An evolutionary explanation for obesity has been put forward based on biological preferences for foods which cause overeating and problems with weight in our modern world, which has been called an “obesongenic environment”. There are many factors in our environment, such as fast food outlets and cars, which encourage an unhealthy lifestyle and may contribute to higher levels of obesity.

Like biological explanations, evolutionary explanations of eating might be regarded as an oversimplification by suggesting that adaptiveness is the single, guiding principle. Such explanations are also determinists as they propose that eating behaviour is determined by past environments, thereby overlooking the notion of free will and the fact that human behaviour is affected by many other factors such as thought, emotions and social factors. Evolutionary drives are moderated and modified by social drives. Evolutionary approaches can explain innate food preferences that were important for our ancestor’s survival. An innate preference for sweet foods may lead us to consume energy-dense foods, such as chocolate bars, which are longer needed in the current obesogenic environment of the Western world, and can help to explain the recent upsurge in obesity. Innate preferences for food can be used to demonstrate the wisdom of the body, the existence of biological drives and also the importance of the environment. It is also difficult to measure eating behaviour accurately in a research context. The central concept of adaptiveness can be applied to many behaviours, including eating and is difficult to demonstrate empirically or disapprove. This means that we have no means of establishing the validity of the explanation. A strength of evolutionary explanations is that they consider ultimate causes and so may lead to more valid ways of treating seemingly maladaptive behaviours by taking account of their adaptive significance and not merely focusing on the proximate problem. Evolutionary explanations appear to suggest that we are no longer adapting to changing environmental conditions. Some scientists believe that humans are continuing to evolve both physically and psychological and are doing so at a faster rate that any other close species.