Rips et al.'s proposition cannot account for the facts that (1) a historical look at the word number systems suggests that the concept of natural numbers has been progressively elaborated; (2) people from cultures without an elaborate counting system do not master the concept of natural numbers; (3) children take time to master natural numbers; and (4) the competing advantage of the postulated math schema in the natural selection process is not obvious.

Humphreys & Forde concentrate on the living/nonliving dissociation. However, further dissociations have been reported, including selective loss or preservation in recognizing body parts and numbers. This commentary outlines the relevance of the number category for understanding the organising principles of semantic memory.