Alien Logic

The alien instruments couldn't detect carbon-based life forms, but did pick up in detail the traffic on earth's communications systems (phones, internet, etc.), which, to them, seemed to cover the globe with an ocean of pulses -- pulses that, analyzed, proved significant, alive.

Experimentation showed that damaging connections in this system reduced or altered traffic in predictable ways, proving beyond reasonable doubt that this huge electronic brain was THE lifeform inhabiting earth, just as on earth, carbon-based life forms were busy proving to each other by similar logic that they are their brains.