Is the evolution of intelligent behavior universal?

Abstract

Throughout the book we have emphasized one possibility for Evolution of Life in the Universe: the universality of the eukaryotic cell leading up to not a single tree of life (phylogenetic tree), but rather to a "forest of life". This is in sharp distinction with the view that ours is a ’rare Earth’ (cf., Preface). Clearly there are other alternatives, but only experiments carried out in appropriate solar system missions will give us the correct answer. We call the attention of the reader to the fact that experiments designed to select between the alternative pathways of evolution are possible. (It should be underlined though that such experiments are both costly and slow in their implementation.)