1. A biometric index and search apparatus that searches, based on a matching operation, for a probe in a biometric corpus stored in a database, comprising: a plurality of prototype templates; an index processor coupled to the database; a search processor coupled to the index processor and the database; and a typicality processor coupled to the index processor, the search processor, and the database, wherein: the typicality processor performs the matching operation between templates in the biometric corpus and the prototype templates, and averages resulting match scores for each of the templates to generate a template-typicality score for each of the templates; and the index processor generates a typicality-indexed corpus from the biometric corpus by dividing template-typicality scores of all the templates in the biometric corpus into typicality ranges, each typicality range corresponding to a typicality sub-corpus that has about a same number of templates as other typicality sub-corpuses, and each of templates in the typicality sub-corpus having a template-typicality score within a typicality range of the typicality sub-corpus.