We have been applying the mathematics of information theory—originally developed for human communication systems and computers—to humpback whales in order to measure the complexity of their vocalizations. Is their "language" as complex as ours, or even more complex? Are there general rules for communicating knowledge that even messages from extraterrestrial intelligence (ETI) will have to obey? As astrobiology uses Antarctica as a proxy for Mars, so we are using non-human but complex communication systems as a proxy for an ETI signal if and when one may be received. Humpback whales grew up on the same planet, and around the same star, as humans did, but their communication systems are certainly not human! Thus we can deprovincialize our thinking and approach to the detection of intelligent life in space.