Constrained roads to complex brains

Abstract

During the arms race for survival on Earth, highly intelligent biological systems have emerged only a few times. Among vertebrates, mammals and birds can solve complex problems, use tools, and engage in elaborate social behaviors. These sophisticated tasks involve the pallium, the brain region most implicated in cognition, which includes the neocortex in mammals. However, it is unclear whether complex brains evolved multiples times through similar or different mechanisms. On pages 733, 734, and 732 of this issue, Zaremba et al. (1), Hecker et al. (2), and Rueda-Alaña et al. (3), respectively, provide evidence for the convergent development and evolution of neurons and their connections in the bird and mammalian pallia, highlighting the need for multiple perspectives in brain comparative studies.