FIGURE 2.15 Evolution and the Cerebral Cortex The brains of these different animal species have many structures in common, including a cerebellum and cortex. However, the proportion devoted to the cortex is much greater in mammals than in species that evolved earlier, such as fish and amphibians. The relative size of the different structures reflects their functional importance.

[a] Tracy Kahn/Corbis [b] DLILLC/Corbis [c] Photodisc/Punchstock [d] Grove Pashley/Corbis/Jupiter Images