Lecture 11: Emotions, Part I - Function, Faces, Fear and Kin Altruism

What this lecture covers

This lecture opens the course's unit on emotion by arguing that emotions are not an irrational obstacle to good functioning but the mechanism that sets goals and priorities in the first place, illustrated through cases of brain damage that destroyed emotional capacity rather than reasoning ability. It then moves through facial expression research, with particular focus on smiling, before introducing fear as a case study of a universal, evolutionarily shaped emotion, and closing with an evolutionary account of why animals, including humans, are kind to their genetic relatives.

By the end you should be able to explain why the "Spock" model of unemotional rationality is incoherent, distinguish a genuine (Duchenne) smile from a social greeting smile, explain why certain fears (snakes, heights, strangers) are near-universal while others (guns, electrical outlets) are not, and describe how selfish-gene reasoning explains altruistic behavior toward relatives. The lecture continues directly into the following class on social emotions toward non-kin.

Key ideas

• Emotions set goals and priorities: rather than being a hindrance to rational behavior, emotions are what drive curiosity, caution, sociability, and goal pursuit; a purely unemotional agent (the Star Trek "Spock" model) would have no reason to act at all.
• Phineas Gage and "Elliot": patients with damage to the frontal cortex who lost much of their emotional capacity did not become more rational; they lost the ability to prioritize, set goals, or hold a job, showing that emotion and effective reasoning are intertwined rather than opposed.
• Facial expressions and universality: emotional facial expressions like anger and fear are recognizable across cultures and are not learned purely by imitation, since children blind from birth still produce appropriate facial expressions such as smiling.
• Duchenne vs. Pan Am smiles: a genuine happiness smile (Duchenne smile) engages the eyes and is hard to fake, while a social greeting smile (Pan Am smile) is a deliberate communicative signal that mainly involves the mouth; most people cannot fake a convincing Duchenne smile.
• Smiling is communicative, not just expressive: bowlers and Olympic medalists typically do not smile at the moment of success but do smile once they turn to face others, showing that smiles function as social signals of happiness rather than automatic readouts of internal state.
• Universal fears reflect ancestral dangers: humans (and other primates) show strong, easily acquired fears of things like snakes, spiders, heights, and strangers, which were dangerous in the ancestral environment, but not of modern dangers like guns or electrical outlets.
• The "selfish gene" framework: because genes, not individual survival, are what natural selection propagates, animals are expected to evolve kindness toward genetic relatives (kin altruism), since helping a relative also helps copies of one's own genes survive.
• Parent-offspring signaling: infant distress calls and "cute" features (large forehead, big eyes, chubby cheeks) are explained as evolved signals that elicit caregiving, not as intrinsic properties of babies.

Walkthrough

Why emotions are not a flaw (0:00)

Bloom opens with a William James passage arguing that everyday emotional reactions, smiling when pleased, falling in love, feel natural only because of contingent facts about human biology, not because they are logically necessary; a lion's love for a lioness is just as "natural" to the lion. He extends this to questions like why feces smell bad to humans but not to dung beetles, framing the section as training students to treat the seemingly obvious as something requiring explanation. He then critiques the popular idea, exemplified by Spock and Data in Star Trek, that emotion is an obstacle to rational function, arguing that without emotion there would be no motivation to explore, defend oneself, or pursue any goal at all.

Phineas Gage and the loss of emotional capacity (9:06)

Bloom presents the case of Phineas Gage, a construction foreman who survived an iron rod passing through his frontal lobe in 1848 with his intellect, speech, and physical abilities intact, but with a transformed personality: impulsive, profane, and unable to sustain relationships or hold a job. He pairs this with Antonio Damasio's patient "Elliot," whose frontal lobe tumor left his reasoning technically intact but destroyed his ability to prioritize or complete tasks, illustrating that damage to emotional processing, not just to logic, is what undermined their functioning in daily life.

Facial expressions and the psychology of smiling (15:45)

Using demonstrations based on Paul Ekman's research, Bloom shows how specific muscle configurations map onto universally recognizable emotions like anger, drawing on facial expression databases from multiple countries. He then focuses on smiling: smiles appear even in children blind from birth (ruling out pure imitation) and in nonhuman primates, and research on bowlers and Olympic medalists shows that people typically smile only once they turn to face an audience, suggesting smiles function as social signals of happiness rather than automatic emotional readouts. He distinguishes the genuine Duchenne smile, which engages the eyes and is difficult to fake, from the polite "Pan Am" greeting smile, and discusses supporting evidence from studies of married couples' greeting smiles (John Gottman's research) and college yearbook photos correlated with later-life happiness. A third type, the coy or appeasement smile seen in embarrassed or submissive contexts, is also introduced, along with the phenomenon of emotional contagion demonstrated live in class.

Fear as a universal, non-social emotion (32:22)

Bloom introduces fear as a case study because it is basic, largely non-social, shared across many species, and connects to earlier course material on classical conditioning. He lists common, near-universal fear triggers, spiders, snakes, heights, storms, darkness, strangers, and blood, and contrasts them with the comparative rarity of fear toward modern dangers like guns, cars, or electrical outlets, arguing this pattern reflects which threats were dangerous during human evolutionary history rather than which are statistically dangerous today. He cites a study of inner-city Chicago children whose top fears were snakes and spiders despite little direct exposure, and research by Judy DeLoache on infants' predispositions toward these "pre-potent" fear stimuli.

Kin altruism and the selfish gene (36:29)

Bloom introduces the social emotions, starting with those directed at genetic kin, and explains why evolution would produce kindness rather than pure selfishness: a simple two-gene thought experiment shows that a gene promoting offspring care will outcompete one that does not, since reproduction, not mere survival, is what natural selection favors. He extends this with examples of how parasites and viruses (cold viruses, toxoplasmosis, rabies) manipulate host behavior to aid their own reproduction, leading into Richard Dawkins's "selfish gene" framing, where animals are described as vehicles through which genes replicate themselves. J.B.S. Haldane's quip about sacrificing himself for enough relatives illustrates how genetic relatedness predicts the ultimate-causation logic behind kin altruism, including examples like infanticide by new male lions. The lecture ends by describing infant distress calls and evolved "cute" features (big eyes, large forehead) as signals that elicit caregiving, and previews the following class's discussion of Harlow's "wire mother" versus "cloth mother" experiments.

Before you watch

• Recall the earlier lecture on evolutionary psychology and the distinction between ultimate and proximate causation, since this lecture applies that framework directly to emotions and kin altruism.
• The classical conditioning material from the behaviorism lectures is referenced briefly when introducing fear; a quick review of that unit helps but is not essential.
• No prior knowledge of specific researchers (Ekman, Damasio, Dawkins) is assumed; each is introduced as needed.

Check your understanding

1. Why does Bloom argue that the Star Trek portrayal of emotionless rational characters like Spock does not make logical sense?
2. What did the cases of Phineas Gage and Damasio's patient Elliot reveal about the relationship between emotion and effective decision-making?
3. What distinguishes a Duchenne smile from a Pan Am smile, and what evidence suggests smiles are social signals rather than automatic expressions of internal happiness?
4. Why are humans and other primates much more likely to develop fears of snakes and spiders than of statistically more dangerous modern objects like cars or electrical outlets?
5. Using the two-gene thought experiment or Haldane's remark about relatives, explain how the "selfish gene" perspective accounts for altruistic behavior toward kin.