286 Miles per hour for nerve signals traveling in a high priority motor-reflex neuron in the spine--the fastest in the human body apparently.
100,000 miles worth of nerve fibers in the brain sheathed insulating myelin, which boost transmission speeds. The slowest is apparently 1 mph.
1000 times more neural connections than stars in our galaxies.
Truly, we carry a miniature universe within our skulls
Numbers: The Nervous System, From 268-MPH Signals to Trillions of Synapses | Mind & Brain | DISCOVER Magazine
Also, as the author points out, the genes that play a role in the development and operation of our nervous system account for less than 10% of our genomes. That drives home the point that our DNA is much more a general development plan than a blueprint.