What, then, does it mean to be human? As a technological species on Earth we have a semblance of uniqueness. But what about within the cosmos as a whole? Should we doubt our own specialness?
This is the central point of Kershenbaum’s exploration. Pondering scientifically on the concept of the extraterrestrial, of universalities and alternatives, is to hold a full-length mirror up to ourselves. This allows us to deconstruct everything from our physiology to psychology, and so explore why humans are the way we are. To comprehend the alien is to know thyself.
Here, at last, Kershenbaum raises some extravagant possibilities. Cuttlefish use their colour-changing skins to communicate basic emotional states (and hypnotise their prey). The South American knifefish and African elephantfish use electricity-generating organs to sense movement and communicate social status. Animals that can perceive magnetism are “widespread” on Earth. None of these creatures — “as far as we know” — uses these powers to talk, but the possibility that actual aliens might is gloriously, tantalisingly raised.