 This problem aside, there is also some concern about the extent to which it is plausible to suppose that natural selection could act on the fine details of the operation of the brain, such as the firing of neurons in the presence of dogs. (This is an objection raised in Fodor (1990c)). Natural selection might operate to increase the size of the brain so there is more cortical mass for cognitive processing. Natural selection might also operate to increase the folding of the brain so as to maximize the cortical surface area that can be contained within the brain. Natural selection might also lead to compartmentalization of the brain, so that one particular region could be dedicated to visual processing, another to auditory processing, and still another to face processing. Yet, many would take it to be implausible to suppose that natural selection works at the level of individual mental representations. The brain is too plastic and there is too much individual variation in the brains of mammals to admit of selection acting in this way. Moreover, such far reaching effects of natural selection would lead to innate ideas not merely of colors and shapes, but of dogs, cats, cars, skyscrapers, and movie stars. Rather than supposing that functions are determined by natural selection across multiple generations, many philosophers contend that it is more plausible that the functions that underlie mental representations are acquired through cognitive development.