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Day 3 — Wed, Apr 1

Why did evolution bother building emotions?

Most people think emotions are stupid or a sign of weakness. That is a naive take. Emotions are extremely complex to build. If there was no reason to have them, evolution would not have spent the energy. Every basic emotion has a clear survival purpose. Joy and distress are the motivators that keep us doing things that help us survive and reproduce. Then there is crying: only humans have emotional tears, probably because of a mutation. And higher cognitive emotions live in the neocortex while basic ones sit in the much older limbic system.

  • Emotions are not stupid. They are extremely complex to build. If evolution spent the energy, there must be a reason
  • Every basic emotion has a clear survival function: fear, anger, surprise, disgust each map to a specific threat response
  • Joy and distress are the deeper motivators. Without the anticipation of either, there would be no point in living
  • We learn emotions from others too, not just from our own experience. But this has limits
  • Only humans have emotional tears. The reason is surprisingly simple: a mutation. But why we cry at all has a more interesting answer
  • Higher cognitive emotions sit in the neocortex. Basic emotions live in the much older limbic system

The Positive View of Emotions

Emotions are not bugs in human software. They are expensive biological features that evolution built for a reason

  • Most people (and even me two years ago) would think emotions are bad or not a sign of intelligence. That is naive
  • Emotions are extremely complex to build. If there was never any reason to have them, there was no point for them to exist. That kind of emotional evolution cannot be random
  • Otherwise, why did evolution create them? This is the 'positive view' of emotions

The Survival Purpose of Each Emotion

Like we saw previously, every emotion (basic and higher cognitive) has some purpose. Here is what each one does and why evolution built it

  • Fear — to run away from danger (flight). This is the most obvious one. You see a predator, you feel fear, you run. Fear exists because ancestors who ran from threats survived. Those who did not feel fear got eaten
  • Anger — to fight. Anger is the complement to fear. When running is not an option, anger prepares you to stand your ground and fight back. The increased heart rate, the adrenaline, the tunnel vision are all built for confrontation
  • Surprise — response to novel stimuli. When something unexpected happens, the eyebrows arch and the eyes widen. This is not random. Widening the eyes allows you to take in as much visual information as possible. Evolution built this so you can rapidly assess whether a new situation is a threat or an opportunity
  • Disgust — to run away from filth. Disgust keeps you from living in bacteria. The revulsion you feel toward rotting food, feces, or open wounds is evolution saying: stay away from things that carry disease. Without disgust, our ancestors would have died from infections far more often
  • Joy — the motivator. This one is slightly more complicated. Joy is not a direct survival response like fear or anger. It is a reward signal. The reason we have sex, meet people, and receive gifts that make us joyful is that all these things were conducive to the reproductive success of our ancestors. Joy is evolution's way of saying: do more of this
  • Distress — the inverse of joy. The reason death of a friend or loss of an important possession are so distressing is that these things were bad for the reproductive success of our ancestors. Losing allies, resources, or mates reduced your chances of survival. Distress is evolution's way of saying: avoid this
  • Joy and distress together are the motivators to keep doing evolutionarily advantageous things. Joy pulls you toward good outcomes. Distress pushes you away from bad ones
  • Plus, without the anticipation of joy and distress there would be no point in living. If you could not look forward to pleasure or dread pain, you would have no reason to do anything at all

Learning Emotions from Others

Emotional knowledge is not limited to personal experience. We learn from watching other people

  • Children seeing their parents avoid a certain river for bathing would already learn the danger without having to try themselves
  • But this has a limit. The learned behaviour must be under a threshold of believability. If I see my parents being superstitious, I do not automatically become superstitious
  • Some emotional responses are deceptive. A cat with fear will have raised fur to appear larger. This is common in humans as well and is probably an evolutionary vestige from our furry ancestors

Crying and the Three Kinds of Tears

Only humans have emotional tears. The reason is surprisingly simple

  • It was new to me that there are three kinds of tears: (1) basal tears which constantly lubricate the eye, (2) reflex tears triggered by irritants like smoke, and (3) emotional tears
  • Only humans are supposed to have emotional tears. Other animals cry as well but they do not produce emotional tears
  • Why do we cry when under distress? There is no clear theory yet but the following is convincing
  • When you cry, emotional tears contain high levels of hormones like prolactin and adrenocorticotropic hormone. These tears also lead to reduction in cortisol while causing increased levels of endogenous opioids like endorphins. That is why we have a 'good cry' and feel slightly better
  • Tears can also be social signaling. It is really hard to fake tears, so having tears is a solid sign that someone is in genuine distress. When we cry together it creates a kind of pure bonding
  • Why only humans have emotional tears? A surprisingly stupid reason: mutation. Just a mutation

Where Emotions Live in the Brain

Higher cognitive emotions are newer tenants in a newer building

  • Higher cognitive emotions must be much more recent than the basic emotions. They are present in the neocortex, the outer layer of the brain
  • Basic emotions might be much older because they are present in the limbic system: hippocampus, cingulate gyrus, thalamus, and other subcortical structures
  • This maps to the evolutionary timeline. The limbic system is ancient. The neocortex expanded much more recently, especially in humans