The term "parent clinger" was introduced by the behaviour biologist Bernhard Hassenstein in the 1970s. He contradicts the typus that mammals are stay-at-home`s.
The term describes mammals that need the help of their parents who carry it. Mammals are dependent on their parents - their mothering and the warmth of their bodies. Human children are called "parent-clinger" as well, because of their strong palmar grasp and the reflex to cling to their caregiver.
Even newborns clench their fists to cling to a caregiver intuitively. Thereby it is aligned permanently to a carrying situation. This is especially distinctive, if the baby is tired because in such situation it is probable that the baby falls off the mother.
The ergonomical spread-squat-position is also typical for parent clingers. This position is adopted by a child automatically when it is lifted up. It is the predestinated position to carry a baby on the hip.
If the baby is put down again it starts to scream because it feels mortal fear not to survive without its mother. This is called contact call.
All these reflexes are inherent for shelter.
Being carried also means to feel safe and secure and to be mobile.