27 - Preconditions for Life

Summary

The discussions in this book so far have been about how life evolved on Earth and what paths it took, with the possible situation beyond Earth considered at regular intervals against this background. Some might say this approach is too conservative and that we should think outside the box for a while. After all, life could not just look, but also be very different, in principle, from life on Earth.

Is this really the case? Let’s recap on some of the preconditions for life discussed in previous chapters. To reach the level of molecular sophistication, which we observe on our own planet, the biology of an exoplanet would most likely have to be carbon-based because no other element has the same potential to form such a huge array of different molecules. Another point to remember is that high-level functions, like those humans exhibit, with their large brains and intricate physiologies, would require a complex physical substrate.