The hypothesis of the zoo

The hypothesis of the zoo  is a hypothesis in 1973 by the astronomer John A. Ball in the journal Icarus in response to the Fermi paradox about the apparent lack of evidence of the existence of extraterrestrial life. Under this assumption, the aliens exist and are technologically advanced enough to communicate with earthlings. They observe the Earth and humanity from a distance, without trying to interact, the way of researchers who observed the primitive animals from a distance, avoiding contact so as not to disturb them. Development of this hypothesis is the galactic quarantine where extraterrestrial civilizations would wait before contacting humanity it reaches a certain level of technology or avoid self-destruction. Did Aliens place us on earth?