and Wernickes cortical areas (Dronkers, 2000). Damage to the caudate nucleus, putamen, and internal capsule (structures of the cerebral hemispheres that are deep to the cortex) also appear to play a role in Brocas aphasia, including aspects of syntactic processing (Lieberman, 2000).The evolutionary histories of these areas are quite curious, as homologues to both Brocas and Wernickes areas have been identified in nonhuman primate brains (Striedter, 2005). Exactly what function they play in other species is not currently known, but an evolutionary perspective would predict that they likely process information in ways that would be useful to language (Schoenemann, 2005), consistent with the view of language adapting to the human brain by taking advantage of circuits that already existed. The presence of these areas in nonlinguistic animals is a glaring anomaly for models that emphasize the evolution of completely new language-specific circuits in the human lineage (e.g., Bickerton, 1990; Pinker, 1995). In any case, although detailed quantitative data on these areas in nonhuman primates have not been reported, it does appear that they are significantly larger both in absolute and relative terms in humans as compared to macaque monkeys (Petrides & Pandya, 2002; Striedter, 2005).Given that Brocas and Wernickes areas mediate different but complementary aspects of language processing, they must be able to interact. A tract of nerve fibers known as the arcuate fasciculus directly connects these areas (Geschwind, 1974). The arcuate fasciculus in humans tends to be larger on the left side than on the right side, consistent with the lateralization of expressive language processing to the left hemisphere for most people (Nucifora, Verma, Melhem, Gur, & Gur, 2005).The arcuate fasciculus appears to have been elaborated in human evolution. The homologue of Wernickes area in macaque monkeys does project to prefrontal regions that are close to their homologue of Brocas area, but apparently not directly to it (Aboitiz & Garcia, 1997). Instead, projections directly to their homologue of Brocas area originate from a region just adjacent to their homologue of Wernickes area (Aboitiz & Garcia, 1997). Thus, there appears to have been an elaboration and/or extension of projections to more directly connect Brocas and Wernickes areas over the course of human (or ape) evolution. Recent work using diffusion tensor imaging (which delineates approximate white matter axonal connective tracts in vivo) suggest that both macaques and chimpanzees have tracts connecting areas in the vicinity of Wernickes area to regions in the vicinity of Brocas area (Rilling et al., 2007). However, connections between Brocas area and the middle temporal regions (important to semantic processing; see below) are only obvious in chimpanzees and humans and appear to be most extensive in humans (Rilling et al., 2007). Presumably these connections were elaborated during human evolution specifically for language (Rilling et al., 2007).Prefrontal CortexAreas in the prefrontal cortex (in addition to Brocas area) appear to be involved in a variety of linguistic tasks, including various semantic aspects of language (Gabrieli, Poldrack, & Desmond, 1998; Kerns, Cohen, Stenger, & Carter, 2004;Luke, Liu, Wai, Wan, & Tan, 2002; Maguire & Frith, 2004; Noppeney & Price, 2004; Thompson-Schill et