Scott Page (2011, 166) says that in any evolutionary or developmental process there is a ‘tradeoff between exploration and exploitation.’ Exploitation consists of consuming useful resources; exploration means trying out new options which are not known to be resources. More variation isn’t necessarily better, but ‘some variation is necessary for a complex system to maintain functionality.’
As early as 1937, in the new field of population genetics, Theodosius Dobzhansky demonstrated the value of biological polyversity in keeping ‘populations tuned to changing environments’ so that each species is better equipped to occupy a ‘specific multidimensional niche’ (Depew and Weber 1995, 293-4).
Since that time, populations have been shown to be generally polymorphic, that is, to contain at least several variant alleles for each trait … Dobzhansky’s abiding concern, and lasting contribution, was to insist not only that populations are in fact full of diversity but that diversity is good for them.
— Depew and Weber 1995, 296 (italics theirs).