The fossil record documents trends in which brains that are

The fossil record documents trends in which brains that are large relative to body size evolved in certain lineages, including hominins. In such lineages, what can you infer about the costs and benefits of large brains?

Solution

Natural selecction favored the evolution of larger brains, suggesting that the benefits of large brains outweighed the cost

explanations: cost changes in brain size leads to congnitive benefits but whether those benefits also produce a net fitness benefits depends upon whether the energy costs of an increase brain size are met or whether they generate a sufficient survival or reproductive benefit to overwiegh these energetic costs.