Puberty is triggered by pulsatile release of GnRH from specific nerve cells in the the brain. What signals tell these nerve cells to release GnRH in this manner has not been determined, although it has been suggested that hormones associated with good nutritional status (such as IGF-1) have a role. New research has now confirmed that in mice IGF-1 does indeed have a key role in coordinating the timing of puberty onset.