Snapshot · The School of Greatness
Einstein's brain was actually smaller than average, suggesting that intelligence is driven by the density and number of neural connections rather than raw brain size.
Where this was said
At 39:58 · chapter starts 36:05
Lewis asks how much the brain influences the mind and vice versa. McLaughlin's answer: the brain has machinery to do whatever the mind asks. That machinery includes habit formation, emotional experience, and unconscious threat detection — including olfactory channels for picking up the pheromones of a threatening individual before conscious awareness kicks in. The limbic system (amygdala, hippocampus) triggers the neuroadrenergic fight-flight-freeze cascade. He then offers the Einstein curveball: the physicist's brain was smaller than average, suggesting that the 100 trillion synaptic connections (against 90 billion neurons) are the real intelligence substrate — and can be grown through deliberate learning. The mind, in short, can generate brain growth. Lewis wonders aloud whether any brain surgeon has ever scanned their own brain every five years to track development. McLaughlin has not. [1] — Dr. Mark McLaughlin "90 billion neurons, 100 trillion connections: The human brain contains approximately 90 billion neurons and 100 trillion connections betwee…" 40:30 [2] — Dr. Mark McLaughlin "Einstein's brain was smaller than average: Einstein's brain was actually smaller than average, suggesting that intelligence is driven by th…" 39:58
The human brain has 90 billion neurons but 100 trillion synaptic connections — and you can increase those connections through learning. Even Einstein's brain was smaller than average; it was the connections that made him exceptional. Brain size is irrelevant; connectivity is everything.
The human brain contains approximately 90 billion neurons and 100 trillion connections between them — and those connections can be increased through learning and new skills.
McLaughlin opened a patient's skull only to find the cyst he was looking for had vanished. Four years into his career, alone, no senior partner available. He methodically started over from the scalp — and found the cyst hiding in the upper left field of his microscope. The surgeon who left the OR that day was permanently changed.
The widely cited ego-depletion model — the idea that willpower is a finite resource that gets depleted — failed to replicate in follow-up studies.
Humans are estimated to have 5,000–7,000 thoughts per day, yet can recall essentially none of them afterward, highlighting why in-the-moment emotional tracking matters.
A large Harvard study found that a wandering mind is an unhappy mind — people report greater happiness when their attention is tethered to the present, even if the task is unpleasant.
A key study finding that we have a 'credit card's worth of plastic' in our bodies was likely skewed because researchers used nitrile gloves that shed plastic particles onto the microplastic detector.
Emotionally sensitive people have a hyperactive amygdala, an underactive prefrontal cortex, and a frayed connection between the two — making emotional regulation structurally harder.
Rejection sensitivity can be observed as early as age 2 or 3, suggesting it has strong developmental and likely genetic roots.
A Yale study found that non-judgmental observation of emotions — without rushing to resolve them — reduces activation in the brain, making it a powerful regulation tool.
Dan Gilbert's research found that the psychological immune system — the brain's ability to justify and find satisfaction in choices — activates most powerfully when a decision is perceived as irreversible.
Barry Schwartz's research found that maximizers — people who try to optimize every decision — tend to achieve objectively better outcomes but report lower happiness than satisficers who choose 'good enough.'
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