Scientists at the Max Delbrück Center for Molecular Medicine in Berlin have discovered how naked mole-rat queens prevent other females in their colony from breeding, resolving a long-standing puzzle about these unusual rodents. Naked mole rats live in large underground colonies where, as with ants or bees, only one female reproduces, but researchers had struggled to explain how queens enforced this given that their tunnel networks can stretch for miles, making constant physical policing impractical. The Lewin Lab team found the answer lies in scent rather than aggression, revealing a sophisticated chemical signalling system that also governs how colonies distinguish friend from foe.

By collecting and analysing odour samples from hundreds of mole rats, researchers identified a compound called isopropyl myristate that appeared only in breeding queens, secreted from their genitals and spread through the tunnels as they moved about. Levels of the compound rose and fell with the queen's fertility, peaking during heat or pregnancy, and remained detectable on surfaces for around 24 hours, allowing it to mark territory spanning up to three kilometres of burrows. The team also found that mole rats, which are blind and possess around 1,200 olfactory receptor genes, use distinct colony scent signatures to identify strangers, and that disabling their sense of smell eliminated their otherwise lethal aggression towards outsiders.