Lecture 12 In-Depth Notes on Food Aversions in Evolutionary Psychology - PSYCH 307

Food aversion: is a strong dislike or avoidance of certain foods, often due to negative associations like taste, texture, smell, or past experiences such as nausea or illness after eating that food.
Focus: Differentiate between food preferences and food aversions.
- Food preferences motivate us towards beneficial foods.
- Food aversions prevent us from harmful or dangerous foods.

Hunger Impact: In states of hunger, preferences can diminish, yet aversions remain important to avoid dangerous foods.
Disgust Response: A key mechanism to prevent consumption of harmful substances based on the disgust reaction.

Innate Disgust: Humans are prewired to feel disgust towards certain foods like feces, rotting meat, and mold, reflecting an evolutionary adaptation.
- Example: Images show the contrast between fresh and rotting food highlighting this response.
Cultural Universality: Studies show that disgust reactions are consistent across cultures, indicating a biological basis rather than a learned response.

Theory: Disgust is an evolved mechanism to avoid foods that are likely to harbor microbial contaminants.
EPM Characteristics: Disgust responses are consistently expressed across different cultures.
- No culture endorses consuming feces or moldy food, suggesting biological underpinnings.
Expression of Disgust: There is a universally recognized facial expression of disgust, further supporting the concept of genetic wiring.

Observation: Women show a lower threshold for disgust compared to men.
Interpretation: Tied to evolutionary roles in child-rearing; mothers needed to protect vulnerable offspring from contaminated foods.

Definition: A learned aversion to a food that occurs after a negative experience, such as illness.
Mechanisms:
- Unlike typical classical conditioning, only one trial is necessary to develop a strong aversion.
- Examples are given, such as personal experiences that led to lasting aversions (e.g., crab).
Temporal Separation: The sickness may occur hours after eating the food, allowing the learning process to adapt to delayed onset of foodborne illnesses.

Unique Characteristics:
- Requires only one exposure for conditioning.
- Can occur with a delay between food consumption and sickness.
Evolutionary Reasoning: Fast learning is crucial due to the potential life-threatening nature of contaminated food.

Pregnancy Sickness: Almost universally experienced by women during pregnancy, characterized by food aversions that could protect the embryo.
- Symptoms vary from mild aversions to severe nausea and vomiting.
Implications: Aversive reactions change eating behavior to protect the developing fetus from potentially harmful substances.

Theory: Pregnancy aversions serve as an adaptive mechanism to protect the embryo from harmful foods.
Evolutionary Timing: Symptoms arise just as the embryo begins to develop, coinciding with peak vulnerability.
Aversions to Specific Foods: Women commonly develop aversions to foods more likely to contain harmful substances (e.g., meat, caffeine).

Vulnerability of the Embryo: Significant development occurs within the first trimester, making it susceptible to teratogens.
teratogens: harmful agents that can cause malformation or development issues in the embryo, leading to potential long-term adverse effects.
Food Selection: Many aversions correlate with foods known to be harmful or risky during pregnancy. aversions are also potentially risky like alcohol, and brussel sprouts. they do not develop aversions to breads, grains, or fruits. This suggests that these aversions may have evolved as protective mechanisms to help pregnant individuals avoid substances that could jeopardize fetal development. also, bread is not that old so it may have not yet become an aversion evolutionarily.
Research Studies: Evidence suggests stronger pregnancy sickness corresponds to a lower risk of miscarriage, supporting adaptive functions. women who had very little pregnancy sickness had 3 times more chances of miscarriage.

Cultural Evidence: Pregnancy sickness is reported across a diverse range of cultures, further indicating an inherited biological adaptation.

Potential Costs: Risks of malnutrition and lower energy due to decreased food intake during pregnancy. Thus stored body fat may serve as an energy reserve for both the mother and developing fetus, helping to mitigate the negative effects of food aversions on nutritional intake.
Adaptive Benefits: Protecting the embryo may offset these costs, maintaining viability and health throughout pregnancy. Additionally, by avoiding potentially harmful substances during critical stages of fetal development, pregnancy sickness may reduce the likelihood of birth defects and other complications associated with maternal intake of toxins or pathogens.

Summary: Food aversions, especially during pregnancy, are not merely sickness but adaptations to protect vulnerable offspring from contaminated foods, reinforcing evolutionary strategies.