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.

About the author: Van Wedeen. MD

Van Wedeen, MD is associate professor in Radiology at Harvard Medical School, assistant neuroscientist at Massachusetts General Hospital, and director of Connectomics at Martinos Center, Department of Radiology, Massachusetts General Hospital.

Van Wedeen