Many self-organized systems in nature exploit a sophisticated blend of deterministic and random processes. No two trees are exactly alike because growth is random, but a Redwood can be readily distinguished from a Jacaranda as the two species follow different genetic programs. The value of randomness in biological organisms is not fully understood, but it has been hypothesized that it allows for smaller genome sizes—because not every detail must be encoded. Randomness also provides the variation underlying adaptive evolution.