In these early mammals, this collaborative period between mother and child was relatively short-lived. After a period of childhood development, the bond tends to fade, and the children and mothers go their separate ways. This is how it is for many mammals that spend most of their lives on their own, like tigers and bears. But not all animals separate in adulthood like this. In fact, the simplest, most widely used, and likely first collective behavior in animals was group living, whereby animals of the same species simply clustered together.
