Monkey Business - Robin Dunbar, Dave Gorman and Jo Setchell

What It Covers

Evolutionary psychologist Robin Dunbar and anthropologist Jo Setchell explain primate mating systems, social bonding, and sexual behavior, revealing how brain size determines relationship capacity and immune genetics influence mate selection through scent.

Key Questions Answered

• •Dunbar's Number: Humans can maintain approximately 150 meaningful relationships, structured in layers of 5, 15, 50, and 150 individuals. This limit correlates directly with prefrontal cortex size and can be predicted through neuroimaging scans.
• •Mate Selection Chemistry: Female mandrills choose mates based on immune system compatibility detected through smell rather than visual displays. Males with matching immune genes produce offspring with stronger immune systems, and humans unconsciously select perfumes that enhance their natural odor.
• •Social Brain Scaling: Primate group size hits cognitive ceilings at 15 and 30 individuals, requiring increasingly sophisticated mental strategies like grooming bonds and mentalizing to maintain cohesion. Species living in stable groups develop larger brains than solitary species.
• •Mating System Ecology: Food distribution determines primate social structure. Scarce resources support only solitary females with one male partner, while abundant food enables large multi-male groups. Monogamous species living together consistently show larger brain sizes than those with separate territories.