Snapshot · Modern Wisdom
Research has found that average parental grief levels track the reproductive value of the deceased child, peaking when the child is a couple of years past puberty — the age of maximum reproductive value.
Where this was said
At 48:28 · chapter starts 42:18
Why are men more aggressive, more risk-taking, more interested in casual sex? Stewart-Williams traces all of these to a single upstream cause: variance in offspring number is greater in males. In many species, some males can sire vastly more offspring than any female can produce, while many males sire none. This creates intense selection pressure on males to compete for status, resources, and multiple mates. The famous 40/80 statistic — that only 40% of ancestral men reproduced versus 80% of ancestral women — comes up, and Stewart-Williams pushes back: he thinks the male reproductive skew in humans was actually lower than in most mammals, precisely because humans have unusually high biparental care. He explains why a 50-50 sex ratio is evolutionarily stable even when one male can theoretically service many females, using a clean parental-investment argument. Bateman's original principle and Trivers' extension to all forms of parental investment — gestation, birth, nursing, and beyond — are outlined clearly.
The commonly cited figure that only 40% of ancestral men reproduced versus 80% of women is likely an overestimate of male reproductive skew, according to Stewart-Williams, because humans have unusually high levels of biparental care.
For most of human history, approximately 50% of children born did not survive to reproductive age, making infant mortality one of the greatest causes of misery in human history.
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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