From NOVA on PBS: Emergent complexity can arise from simple interactions between agents following rules. The complexity that arises is surprising and challenges our assumptions about whether order comes from the top or the bottom. Life and consciousness are examples of emergent phenomena.

“A property of a complex system is said to be emergent just in case, although it arises out of the properties and relations characterizing its simpler constituents, it is neither predictable from, nor reducible to, these lower-level characteristics.” — Prof. Jaegwon Kim, Oxford Companion to Philosophy