The Evolution of a Complex Brain

Dr. Van Wedeen explains that evolution of the brain must occur with small changes — from a small change in the genome to a small change in the structure to a small change, ultimately, in function.

See more of Dr. Van Wedeen's videos here.

In order to evolve a complex brain you have to start with a simple plan and then have a series of modifications or refinements of that simple plan. In development, a small mistake has to have a small outcome. You can't have a small change in development producing a huge and unpredictable change in the phenotype or in the behavioral phenotype that follows from it. Similarly in evolution. Evolution only works if a small change in the genome produces a small change in the phenotype, which produces a small change in behavioral fitness. Large changes are very likely, overwhelmingly likely, to be destructive. And so for this continuous change-- small change in genome, small change in structures, small change in function-- to work, this principle of continuity of connectivity has to be there.
Posted on BrainLine March 18, 2013.

Produced by Brian King, Vicky Youcha, and Lara Collins, BrainLine.