Biological explanations for eating behavior

The evolutionary explanation for food preference suggests that in order to survive people need to eat and our preference to certain food reflects our ancestor’s adaption to their environment, known as environment of evolutionary adaptation (EEA) in order to aid survival. One of these preferences could be our preference for high calorie food this could be due to the conditions of EEA such as sacre food resources therefore preference to high calorie food would have provided our ancestors enough energy resources in order to stay alive until finding the next meal, thus aiding survival of the species. 

Supporting the importance of high calories in an ancestral diet, Gibson and Wardle (2001) found that high calorie containing bananas and potatoes were more likely to be chosen by children as opposed to fruits, demonstrating an evolved preference for calorie rich foods. 

However, this study can be challenged for possibility in lacking validity as the children may have chosen high calorie food over fruits due to famarility by social learning not an innate evolved mechanism from our ancestors. Furthermore, this suggests that evolutionary theory is deterministic as the theory proposes our food preference are innate evolved mechanisms from our ancestors and ignores the influence of other factors such as social learning theory. This suggests that our preferences are learned from modelling our parent’s behaviour as opposed to deterministic evolved mechanisms. 

Additionally, the evolutionary hypothesis is only based on speculation, as we cannot travel back in time to see what adaptive problems our ancestors faced, therefore these assumptions may not be correct. Consequently this means the evolutionary hypothesis lacks in reliability as there can not be any direct empirical evidence supporting the influence of EEA on our food preference. 

On the other hand, we can look at related species such as chimpanzees who face similar adaptive problems today. Such study, Stanford (1999) found that if chimpanzees face starvation they would kill another monkey and go straight for the fattiest parts (e.g brain and the bone marrow), supporting the idea that our preference to high calorie food could be linked to the food scarey from the EEA of our ancestors. 

However, even though this suggests the possibility our preference of high calories come from our ancestral line, applying animal research to human behaviour may not be applicable even though our genetics may be similar, chimpanzees are not exposed to the same environmental factors that can influence modern day humans such as the media. Therefore conclusions made from animal research lacks in validity as it can not be generalised to humans. 

Another biological explanation is how the role of neural mechanisms can control and/or influence our food preferences. Research has found that neural control of cognitive factors in hunger originates in the amydala. The amydala’s role is thought to have influence on the selection of foods based on previous experience. For example, Rolls and Rolls (1973) found that surgically removing the amydala in rats could cause the animals to consume both familiar and unfamiliar foods. 

Such research in to the role of amydala could provide useful understanding of how to treat damage to amydala such as Kluver-Bacy syndrome. Patients suffering from this syndrome experience increased appetite and indiscriminate eating; this suggests that research in the damage to the amydala may have high ecological validity due to the similarity in symptoms after the initial damage in research and real life situations. This suggests treatments developed from neural research may be effective in treatment of Kluver-Bacy syndrome, this making the theory very useful due to its real world application value. 

However, the biological approach can be criticised as being very reductionist, as it is only concerned with the role of physiological and neural systems influencing food preference and ignores social influences such as the media. Social influences influence individuals differently due to differences in interpretation of sensory information, which has very little to do with our biology and more to do with our social experiences. While some research argues that our personality can be changed by alteration of brain structure, which could in turn change our food preferences. Our personality is also influenced by social factors, thus supporting the idea that the biological approach is reductionist in its claims.

Yet reductionism can have its positives. By using the biological approach, treating Kluver Bacy by use of drug therapy can help to alleviate their increased feelings of hunger which in turn would help reduce weight gain and prevent obesity. Suggesting the biological approach is a useful aspect that should be considered especially for treatment of certain food behaviours. 

Another mechanism that could explain some food preferences is taste aversion. This is where an individual has developed adaptive avoidance to a certain food that has made them ill. Taste aversion would have been useful in the EEA of our ancestors as preventing illness would promote their survival. An example of this, Garcia et al (1997) found that by making wolves sick with poisoned lamb meat, afterwards they would avoid live sheep that they would normally attack, this shows the wolves have developed an aversion to lamb meat as it was poisoned, therefore their adaptive avoidance is promoting their survival. 

This study could be challenged for not being applicable to humans due to animal research, however morning sickness in humans can be interpreted as a type of taste aversion as it involves nausea to avoid certain foods such as tea and eggs, in order to aid survival of the embryo. This is referred to as the embryo protection hypothesis (Profet, 1992), as adaptive avoidance of these foods protect the developing baby by foods that could cause harm. Tea contains high levels of caffeine, which could affect developing organs, while eggs contain bacteria such as salmonella that can create illness. This is an excellent example of how evolution has influenced food preference to protect the species, thus supporting the concept of taste aversion. 

However, could all food preferences be a product of evolution? In modern day society, we have advanced knowledge concerning food that our ancestors may not have had, such as sanitation and cooking food to kill bacteria that could harm us. Additionally, our lifestyle has changed dramatically and therefore a diet high in calories is not something that is beneficial in today’s society due to the risk of developing obesity. This suggests that as our environment has changed since our distant ancestors, that extrapolating speculations makes the evolutionary explanation for food preference lack in temporal validity as it may not apply to modern day life.

On the other hand, research into the adaptive origins of taste aversion has been helpful in understanding food avoidance that can occur during cancer treatments and subsequently understanding taste aversion has developed the scapegoat techquie to prevent aversion to familiar foods in patients. Without the technique in place could result in detrimental effects to the cancer patient’s usual diet.

The scapegoat technique developed through research into the consequences of taste aversion, such study by Bernstein and Webster (1980) found that when giving patients ice cream prior to chemotherapy, they developed an aversion to that particular ice cream. This supports the idea that aversions can develop when sickness is present, thus suggests illness can influence our preferences to food, in relation to taste aversion.