KeywordsFood Environment Food Selection Social Facilitation Specialized Eater Food Neophobia
A fear of the unfamiliar. Food neophobia refers to the tendency to avoid eating unfamiliar foods.
Food neophobia – a fear of eating unfamiliar foods – differs from picky eating or simply being a little fussy. Although there is evidence that these characteristics are correlated (Pelchat and Pliner 1986), neophobia serves as an evolutionary survival mechanism. Some mushrooms, for example, contain harmful toxins, so we are rightly cautious when we come across one in the wild. This initial neophobia could protect us from digesting a possibly lethal substance. In our current, food-saturated, and highly processed eating environment, it is perhaps difficult to imagine these sorts of life-or-death decisions having a great impact on us. However, they would have been very real problems for our ancestors. Through natural selection, then, these problems shaped the behavioral and cognitive mechanisms that underlie our eating behavior today. In the following discussion, to outline the evolutionary significance of neophobia, it will be considered in the context of (1) the Omnivore’s Dilemma, (2) neophobic behaviors in infancy, and (3) the possible mediating role of disgust.
The Omnivore’s Dilemma
The Omnivore’s Dilemma (Pollan 2006) or Omnivore’s Paradox, as it was initially described (Rozin 1976), refers to the conflict we omnivores face when deciding what to eat. On the one hand, we are neophiliac, and crave variety, right down to our underlying metabolic processes. As Pollan describes, human metabolism requires Vitamin B12, sourced only from consuming animals, and Vitamin C, which we can only derive from plants. On the other hand, we are neophobic, instinctively worried about the unknown, and for good reason. Plants have evolved mechanisms to ward off predators, including producing harmful poisons and toxins. The evolved survival mechanism of neophobia is shared with rats too. In a now seminal paper, Paul Rozin (1976) demonstrated that when faced with a novel food item, rats sampled only a small amount, as a means of testing the dietary consequences of consuming it. In contrast, for specialized eaters such as koalas, no cognitive effort is required to assess the potential danger of a would-be consumed food item. They are hardwired to treat eucalyptus leaves as food and anything else as nonfood. More complex processing is required in the digestive systems of these more specialized eaters, to derive the nutrients they need from their food source. There are evidently various solutions to the problem of food selection, which have evolved over evolutionary time. For omnivores, more complex cognitive processing (including neophobic reactions) allows us to navigate our food environment, while for more specialized eaters, the guts do the work.
Some of the cognitive processing that occurs to aid us in food selection is relatively low level. However, beyond early processing biases against bitter foods, or initial neophobia, for example, more complex processes have evolved. Notably, enhanced memory capacity, the ability to communicate and share information, and, more broadly, culture have all had an impact on the Omnivore’s Dilemma. As Pollan (2006) suggested, for nonspecialist eaters with few constraints on food selection, “if nature won’t draw a line around human appetite, culture must step in” (p. 298). Cuisine is one example of a cultural phenomenon that has altered our ability to overcome the Omnivore’s Dilemma. This is the set of rules by which a culture prepares and eats food, including what is and is not safe to eat and what flavors and cooking practices are used to prepare food. In a sense, they are an “accumulated wisdom” about how to eat (Pollan 2006). Spices, for example, are used in many cultures to encourage familiarity with otherwise novel foods, working to reduce neophobia. The use of familiar flavors is also noted as important for reducing neophobic behaviors in children (Wardle and Cooke 2008). Thus low-level biases against bitter tastes, which can signal toxicity, work in concert with higher-level mechanisms including the ability to memorize and communicate what is safe, to help overcome the Omnivore’s Dilemma, and ultimately to help us decide what to eat.
Infants and Neophobia
Neophobia works in conjunction with highly specified learning mechanisms to help infants navigate their food environment (Birch 1999). As Birch describes, one study from her research group found that neophobic reactions in two year olds do not go away through the repeated opportunity to smell or look at novel food; infants must be given the opportunity to taste the foods directly. This suggests that increased familiarity, which is well documented to enhance preferences in various domains (known as the “mere exposure effect”; Zajonc 1968), is not enough to reduce neophobia. What is important, however, is the ability to learn about the adaptive consequences of eating a novel food. There is some evidence that children prefer to eat food items separately rather than mixed together (Cashdan 1998), which is consistent with the idea that infants are “reviewing” the dietary consequences of novel foods. As described by Birch, this evidence is consistent with the sorts of processes that are found in rats, who use learned safety as a mechanism in their food selection (e.g., Rozin 1976).
The ability to learn from others is also crucial in deciding what is safe to eat, and there is evidence that social facilitation reduces neophobia in infants. Again, the presence of food alone is not enough to encourage infants to eat, but watching an adult eat something increases the likelihood that an infant will do so also. Interestingly, there may be specificity in this social facilitation, and recent evidence demonstrated that infants learned the edibility of plants, but not artifacts, when watching these objects being placed into an adult’s mouth (Wertz and Wynn 2014).
The timeline of neophobia in infants demonstrates a curvilinear relationship with age (Birch 1999). It is minimal in infancy; for example, infants who are just beginning to eat solid food need only a single positive experience with a novel food, to enhance their preference for it, and other similar foods (Birch et al. 1998). Parents also rate infants between 1 and 2 years as most receptive to new foods (Cashdan 1998). This is probably adaptive, as infants who are not yet able to forage for themselves should be fairly open to available food sources provided by their parent, to ensure nourishment. For children between 2 and 3 years, and to a lesser extent 3–4 years, parents report that children are less receptive to new foods (Cashdan 1998). Neophobia then generally decreases with age, as children and adults experience cuisine and learn the rules associated with eating, which can serve to reduce neophobia (as discussed previously).
Neophobia and Disgust
The emotion of disgust has likely evolved to help us to avoid harmful pathogens and parasites. It is possible, then, that disgust plays a role in neophobia, and this has been suggested by various authors in the field. Recent work by Al-Shawaf and colleagues has demonstrated a direct link between trait-level disgust and trait-level food neophobia (Al-Shawaf et al. 2015). Notably, those who were more neophobic had greater sexual- and pathogen-disgust sensitivity. These researchers also found that males who exhibited higher preferences for short-term mating reported lower food neophobia (more openness to trying new foods). The authors proposed a preliminary hypothesis regarding these findings, suggesting that neophilia could be a form of mating display for short-term mating scenarios. They argue that if (1) a willingness to consume potentially pathogenic and harmful food is a sign of immunocompetence and (2) at least one factor that is considered in female mating decisions is immune health of the male (good genes) – especially in short-term mating contexts – then (3) neophilia (and a lack of disgust around new food) would serve as a mating display, an honest signal of good quality genes. This hypothesis is preliminary, and as the researchers note, more work is required. However, it certainly provides an interesting outlook on neophobic behaviors and evolutionary pressures that may underlie them.
The Omnivore’s Dilemma sheds light on neophobia, and neophilia, and a number of other sensory and cognitive tools we have evolved to help solve the problem of eating. For infants, there is good evidence of specified mechanisms present from a young age, which enable them to navigate their food environment. This includes learning mechanisms that enable behavioral flexibility, including the ability to fully overcome their initial neophobia. It is likely that neophobia is related to the emotion of disgust, and preliminary evidence suggests a further relationship with mating strategy. Further research will continue to enhance our understanding of this fascinating phenomenon, and like with many other “quirks” of human behavior, evolutionary reasoning may prove to be an essential basis for this.