Evolution designed an economical system where a single, subconscious "kinship estimate" for each person dictates both altruism towards them and sexual aversion. It's one calculation for two different social behaviors, determining how close your heart should be and how far your genitals should be.

Humans evolved to have different "drugs of choice" as a survival mechanism. If everyone sought the same rewards, groups would quickly deplete a single resource. This once-adaptive trait now makes us vulnerable to a wide array of modern, hyper-stimulating temptations.

When asked to imagine incestuous acts, women's disgust is uniformly high. Men's responses show a much wider variance. This reflects the catastrophic evolutionary cost of a single bad reproductive choice for a female (nine months of gestation) versus the far lower opportunity cost for a male.

Charles Darwin first struggled to fit altruism into his theory of natural selection, viewing self-sacrifice as a trait that wouldn't be passed on. He later recognized that cooperation provides a key evolutionary advantage—a view now widely supported, though the "selfishness succeeds" myth persists in the collective imagination.

The "rich gay uncle" hypothesis suggests homosexuality persists by shifting reproductive effort. Instead of having their own children, gay men may invest heavily in their siblings' offspring, promoting the survival of shared genes through kin selection. This is supported in some, but not all, cultures.

Anxiety is not always a pathology but can be a purposeful signal. A study on chimps showed that removing the most sensitive, anxious members led to the entire group's demise, as they were the advance warning system for dangers. This reframes anxiety as a crucial societal function.

The 'lie' of monogamy is not that it's a bad choice, but that culture has sanctified it as the only valid path. This framing turns non-monogamous people into villains and ignores that polygyny is the biological norm for most animals, including pre-agrarian humans.

People's conscious, stated reasons for their actions (proximate explanations) often obscure deeper, unconscious evolutionary drivers (ultimate explanations), such as the drive to reduce mating competition while appearing compassionate.

It's a profound mystery how evolution encoded high-level desires like seeking social approval. Unlike simple instincts linked to sensory input (e.g., smell), these social goals require complex brain processing to even define. The mechanism by which our genome instills a preference for such abstract concepts is unknown and represents a major gap in our understanding.