Males that have not established such territories sometimes form small bachelor groups. While keeping them as pets is not advised (like many other nonhuman primates, they are considered likely sources of diseases that can cross species barriers), it is certainly done. Equally, they are highly likely to attract attention from customs officials on importation into many countries. Reports from veterinary and zoological sources indicate captive lifetimes of 12.0 to 16.5 years, suggesting a natural lifetime over a decade. Galagos communicate both by calling to each other, and by marking their paths with urine. By following the scent of urine, they can land on exactly the same branch every time. All species of galago produce species-specific 'loud calls' or 'advertisement calls'. These calls have multiple different functions. One function is long-distance identification and differentiation of individual species, and scientists are now able to recognize all known galago species by their 'loud calls'. At the end of the night, group members use a special rallying call and gather to sleep in a nest made of leaves, a group of branches, or a hole in a tree. Galagos have remarkable jumping abilities. The highest reliably reported jump for a galago is 2.25 m. According to a study published by the Royal Society, given the body mass of each animal and the fact that the leg muscles amount to about 25% of this, galago's jumping muscles should perform six to nine times better than those of a frog. This is thought to be due to elastic energy storage in tendons of the lower leg, allowing far greater jumps than would otherwise be possible for an animal of their size. In mid-flight, they tuck their arms and legs close to the body; they are then brought out at the last second to grab the branch. In a series of leaps, a galago can cover ten yards in mere seconds. The tail, which is longer than the length of the head and body combined, assists the powerful leg muscles in powering the jumps. They may also hop like a kangaroo or simply run/walk on four legs. Such strong, complicated, and coordinated movements are due to the rostral half of the posterior parietal cortex that is linked to the motor, premotor, and visuomotor areas of the frontal cortex. The bush baby also refers to a myth that is used to scare children to stay indoors at night. Most likely arising from the baby-like cry, the unusual nature evolved into a myth about a powerful animal that can kidnap humans.