title: The Cosmic Zoo: The (Near) Inevitability of the Evolution of Complex, Macroscopic Life.
abstract: Life on Earth provides a unique biological record from single-cell microbes to technologically intelligent life forms. Our evolution is marked by several major steps or innovations along a path of increasing complexity from microbes to space-faring humans. Here we identify various major key innovations, and use an analytical toolset consisting of a set of models to analyse how likely each key innovation is to occur. Our conclusion is that once the origin of life is accomplished, most of the key innovations can occur rather readily. The conclusion for other worlds is that if the origin of life can occur rather easily, we should live in a cosmic zoo, as the innovations necessary to lead to complex life will occur with high probability given sufficient time and habitat. On the other hand, if the origin of life is rare, then we might live in a rather empty universe.
authors.affiliation: Department of Earth, Atmospheric and Planetary Science, MIT, 77 Mass. Ave., Cambridge, MA 02139, USA. bains@mit.edu.|Rufus Scientific Ltd., 37 The Moor, Melbourn, Royston, Herts SG8 6ED, UK. bains@mit.edu.
authors.forename: William
authors.initials: W
authors.lastname: Bains
authors.affiliation: School of the Environment, Washington State University, Pullman, WA 99164, USA. dirksm@wsu.edu.|Center for Astronomy and Astrophysics, Technical University Berlin, Berlin 10623, Germany. dirksm@wsu.edu.
authors.forename: Dirk
authors.initials: D
authors.lastname: Schulze-Makuch
keywords: complexity; evolution; great filter; key innovation; multicellularity; origin of life; transition