More boys are born, yet women end up outnumbering men

Human births tilt male, with slightly more boys than girls. Yet by the time people reach sexual maturity, women outnumber men. The population starts out male-biased and flips somewhere along the way. The material doesn't say when or why. Higher male mortality in childhood and adolescence is the usual suspect, but that explanation is not in the source. The sex ratio is a quiet statistic that changes sign as a generation ages, and it shapes everything from marriage markets to pension payouts.