Deep Survival: Who Lives, Who Dies, and Why

Rock climbers belay by fixing a rope to an anchor or another person and attaching it to their harness as a safety back-up in case they fall. Climbers can belay up or down a mountain surface. Gonzales mentions belaying in many of his mountaineering stories. He emphasizes that belaying from a fixed anchor is always the safest option, since sometimes climbers attach themselves by rope to each other to belay, which can cause a fatal domino effect if one climber falls and pulls the others down with them.

Throughout Deep Survival, Gonzales uses a nontraditional definition of emotion that categorizes things most people would agree are emotions (like fear and joy) as instinctual responses. This allows him to draw a neat line between logic and all other responses to situations, which clarifies many of his arguments.

Gonzales does not think humans in survival situations should attempt to eschew all emotion; many emotions, he says, are good survival tools. However, emotions are consistently posed as the less reasonable side of the dichotomy that needs to be tempered by cold logic.

The hippocampus is a large brain region that, among other things, stores memories and plans. Because both plans and memories share the same “storage,” the distinction between future event (plan) and past event (memory) is often blurrier in the human brain than people like to think it is.

Gonzales references this brain region’s functioning in his discussion of how humans can grow as attached to their mental models as to certain memories, and deny evidence that contradicts those memories.

A mental model is a person’s imagined, hypothetical version of a future event. The author explains that people create mental models by projecting past experiences into the future. For example, if someone has climbed a mountain before, they will likely consciously or unconsciously project their past experience onto their mental model of their next hike, assuming that it will unfold similarly. Because people store their mental models in the same brain region as real memories, it is easy for these models to feel real and influence decision-making. Gonzales explores the inherent bias in how humans use mental models to plan, noting that once people create a certain model of a situation, they tend to interpret new information as confirmations of their model. Gonzales urges the reader to make careful plans but always be open to changing them, since doing so will aid survival.

The neocortex comprises nearly half of the human brain’s total volume and is thought to be the seat of higher cognition and reasoning. Gonzales discusses the neocortex mostly in context of the amygdala to compare the speeds at which these brain regions process information. He says that because the neocortex is slower, panic (which is facilitated by the amygdala) always outpaces reason.

Climbers rappel down cliffs by holding onto a rope that is looped under one leg and across their opposite shoulder. Gonzales refers to rappelling in numerous mountaineering anecdotes, such as when Yates and Simpson rappelled down the Siula Grande in Peru.

Risk homeostasis is a psychological phenomenon in which a person sets a limit for how much risk they are willing to tolerate on a given occasion. If they feel something about the experience falls short of the risk they were expecting, they may make riskier decisions in order to meet their pre-decided threshold. Alternatively, if one part of an adventure seems to be less risky than the others, the person may make riskier decisions so the risk levels are congruent across the trip. This phenomenon is clearest in the example of the Mount Hood climbers, who were experienced at climbing but still made reckless decisions that ended in multiple deaths.

The risk-reward loop describes a style of human learning in which a person seeks out moderately stressful situations to test their skills and abilities so they know what they’re really capable of. Gonzales uses the example of a baby learning to walk: The baby has to keep trying, in increasingly difficult situations, before they can feel confident in their ability to walk. However, the lessons gained through this type of learning are stored as emotions rather than cognitively accessible memories. Gonzales uses this concept to lead into an explanation of somatic markers.