Men given a dose of oxytocin, a hormone known to promote feelings of love and trust, have revealed the chemical’s dark side: It made them more ethnocentric. When asked to resolve a moral dilemma, such as choosing to save five lives from a runaway train by sacrificing one life, oxytocin-sniffing Dutch men more often saved fellow countrymen over Arabs and Germans than those who didn’t get a hormonal whiff. (via ‘Cuddle Chemical’ Also Fuels Favoritism, Bigotry)