psyc201 3

What is evolutionary mismatch?

when our ancient brain meets the modern world. The environment has changed rapidly but our brains havent caught up

Adaption are…

context dependent, not universally optimal

SERT s-allele

the short variant of the serotonin transporter gene makes you more sensitive to your environment. In a supportive, stable environment this is great. But it also increases risk of depression, anxiety, and PTSD under adversity.

ADHD

highly adaptive in dynamic, unpredictable hunter-gatherer settings (constant novelty-seeking, quick reactions) — but disruptive in structured classroom/work environments.

Anxiety

heightened threat detection was survival-critical. In modern life, it can become excessive avoidance with no adaptive payoff.

Depression

may have evolved as energy conservation during illness or as social signalling of need. But prolonged depression in modern contexts becomes maladaptive.

natural selection

traits that help survival and reproduction spread through the population. Requires variation, heritability, and selection pressure.

Sexual selection

evolution driven by mate choice and competition. Can produce traits that are actually costly to survival (e.g., a peacock's tail) — they persist because they attract mates. Drives status-seeking, risk-taking, aesthetic preferences.

Honest signalling

only individuals with genuinely good genes can afford to produce costly signals — so they reliably indicate fitness. You can't easily fake them

Gene-culture co-evolution

genes and culture shape each other. Example: lactose tolerance evolved in populations that domesticated cattle. Rice-farming cultures (more collectivist) show higher SERT s-allele prevalence — greater environmental sensitivity was adaptive in interdependent societies

phenotype

Genotype + Environment + Interaction (the two shape each other)

Rice farming is labour-intensive and requires cooperation between people → linked to

collectivist values

Wheat farming is less interdependent → linked to

individualist values

What is SERT, and what does it do in the brain?

SERT (Serotonin Transporter) is a protein that clears serotonin from the synapse after it has been released — it's like a clean-up crew that hoovers up leftover serotonin.

What is a gene polymorphism? What are the two variants of the SERT gene?

A polymorphism is a common genetic variation — like a different version of the same instruction.The two SERT variants are:• Short (S) allele → less SERT protein → more serotonin stays in the synapse-> higher environmental sensitivity (more common in collectivist). Long (L) allele → more SERT protein → less serotonin in the synapse-> lower en

organising effects (prenatal/early life)

hormones shape the developing brain permentantly, they set up neural circuits that will be triggered later. this also happens in puberty

Testosterone plays the major role in…

sexual differences. These effects are long lasting and irreversible

activating effects (adult life)

hormones directly influence behaviour in the moment, within a limited time window. E.g. a testosterone surge before a competition increases dominance behaviour. These effects are temporary and reversible.

Congenital adrenal hyperplasia (CAH)

the adrenal glands overproduce androgens (including testosterone) due to a cortisol synthesis defect (think the body doesn't have cortisol). This exposes a genetically female foetus to higher-than-normal testosterone levels prenatally.

early hormone exposure shapes the….; later hormones activate the….

stage, play

evidence that early hormone exposure has organising effects on behaviour

girls born with CAH show increased preference for typically male associated toys

Sex (biological) is determined by

chromosomes and reproductive organs — but even this exists on a spectrum (intersex conditions occur in ~1% of births).

Gender (identity) is how a person

perceives themselves — shaped by genetic, hormonal, neural, and environmental factors.

Oxytocin ("the cuddle chemical")

released during childbirth, breastfeeding, and social interaction. Critical for maternal behaviour and social bonding. May also promote in-group bonding and out-group aggression — it's not purely peaceful.

Vasopressin

crucial for pair bonding, social behaviour, and paternal care. Prairie voles (monogamous) have higher vasopressin than closely related meadow voles (non-monogamous). Humans with less-active vasopressin receptors are less likely to marry and more likely to divorce.

shared neural circuitry

romantic love and parental love activate strikingly similar brain regions — especially areas rich in oxytocin/vasopressin receptors and the reward system. Looking at your baby activates the same reward circuits as romantic attraction.

Sexual motivation

testosterone primes the hypothalamus (especially the MPOA) to release dopamine, driving the motivational aspect of sexual behaviour. Serotonin inhibits dopamine release (which is why some SSRIs reduce libido).

What are hormones, where are they released from, and how fast do they act?

Hormones are chemical messengers released by the gonads (and other glands) directly into the bloodstream.They are the slowest of the three signalling types — they act over longer timescales and influence the whole body, not just one location.Example: oestrogen promotes sexual receptivity and controls ovulation timing.

What is the key job of a hormone — what is it doing in simple terms?

Hormones act like messengers carrying a signal from the brain to somewhere else in the body — they travel through the blood to reach distant target organs.Because they travel through the bloodstream, they're slow but have a widespread, whole-body effect.

What are neuropeptides, where are they released from, and how fast do they act?

Neuropeptides are released by neurons or the hypothalamus.They are moderate in speed — faster than hormones, slower than neurotransmitters.Uniquely, they can act as hormones, neuromodulators, or neurotransmitters depending on where in the body they are.Example: oxytocin increases during childbirth and social interaction, prompting social bonding and maternal care.

What does it mean that neuropeptides work via an 'indirect route'?

Rather than directly triggering a behaviour themselves, neuropeptides often help other neurotransmitters or hormones have a stronger or different effect — they modulate what's already happening.Think of them as a volume dial — they don't play the music, they turn it up or down.

What are neurotransmitters, where do they act, and how fast are they?

Neurotransmitters are the fastest signalling molecules — they act in milliseconds.They act at synapses in brain circuits controlling sexual arousal, motivation, and reward.Example: dopamine surges during mating-related reward processing.

What is the activating effect of sex hormones?

the direct, temporary influence of sex hormones on behaviour

Is it always hormones → behaviour? Or can it go the other way?

Yes, hormones can trigger behaviour — but behaviour can also change hormone levels.

sex hormones have both

organising (developmental) and activating (temporary) effects on neural circuits and behaviour