http://en.wikipedia.org/wiki/1918_flu_pandemic http://en.wikipedia.org/wiki/1918_flu_pandemic mentions two theories why the 1918 flu pandemic ended (see sectio

http://en.wikipedia.org/wiki/1918_flu_pandemic http://en.wikipedia.org/wiki/1918_flu_pandemic mentions two theories why the 1918 flu pandemic ended (see section 'End of the pandemic'). I'm trying to understand the mutation theory. How come there is no 'watchmaker' situation here? Is it because a virus is simple enough that its replication is directly driven by thermodynamics, as opposed to more 'organized' forms of exploring the configuration space?