When the first draft of the Human Genome Project came to completion at the turn of the millennium, one of the great surprises was that humans have only about twenty thousand genes. This number came as a surprise to biologists: given the complexity of the brain and the body, it had been assumed that hundreds of thousands of genes would be required. So how does the massively complicated brain, with its eighty-six billion neurons, get built from such a small recipe book? The answer pivots on a clever strategy implemented by the genome: build incompletely and let world experience refine. Thus, for humans at birth, the brain is remarkably unfinished, and interaction with the world is necessary to complete it.
One very exciting part of this livewiring is the brain’s ability to process whatever information it receives… and that we don’t need to limit ourselves to our nature-given senses. How about drone pilots intuitively feeling the drone’s pan, tilt, yaw, and acceleration? How about feeling the direction of magnetic north? How about being able to sense infrared light? David talks about this in his excellent TED talk:
How the brain processes sensory information, and the idea of giving people new senses, is only one part of the book. David sees seven key principles; in his words:
- Reflect the world. Brains match themselves to their input.
- Wrap around the inputs. Brains leverage whatever information streams in.
- Drive any machinery. Brains learn to control whatever body plan they discover themselves inside of.
- Retain what matters. Brains distribute their resources based on relevance.
- Lock down stable information. Some parts of the brain are more flexible than others, depending on the input.
- Compete or die. Plasticity emerges from a struggle for survival of the parts of the system.
- Move toward the data. The brain builds an internal model of the world, and adjusts whenever predictions are incorrect.
The book discusses these topics at length in an engaging mix of opinionated explanation, discussion of scientific studies, and real-world anecdotes illustrating the principles.
For example, to illustrate the brain’s ability to adapt to different body plans, David recounts the story of Faith, the dog who learned to walk on two legs. Evolution certainly didn’t evolve dog brains to walk on two legs… but it did create a brain flexible enough to figure it out.
The Wall Street Journal says, “since the passing of Isaac Asimov, we haven’t had a working scientist like Eagleman, who engages his ideas in such a variety of modes. Livewired reads wonderfully, like what a book would be if it were written by Oliver Sacks and William Gibson, sitting on Carl Sagan’s front lawn.”
5/5 - David has a fascinating view of the marvel that is the brain, and he explains it in well-written, engaging, and informative prose. I dig it.