not getting sleepy ? why hypnosis doesn ’ t work for everyone

In the wilds of Africa, when it’s time for a family of elephants gathered at a watering hole to leave, the matriarch of the group gives the “let’s-go rumble” — as it’s referred to in scientific literature — kicking off a coordinated and well-timed conversation, of sorts, between the leaders of the clan. First, the head honcho moves away from the group, turns her back and gives a long, slightly modulated and — to human ears — soft rumble while steadily flapping her ears. This spurs a series of back and forth vocalizations, or rumbles, within the group before the entire family finally departs. This curious behavior, measured and documented in a study published in the October issue of Bioacoustics, shows how this cognitively advanced species uses well-coordinated “conversations” to initiate cooperation within the group, said lead author Caitlin O’ConnellRodwell, PhD, a field biologist and instructor in otolaryngology at the School of How elephants know when to leave the watering hole