  Human sensorimotor control exhibits remarkable speed and accuracy, and the
tradeoff between them is encapsulated in Fitts' Law for reaching and pointing.
While Fitts related this to Shannon's channel capacity theorem, despite
widespread study of Fitts' Law, a theory that connects implementation of
sensorimotor control at the system and hardware level has not emerged. Here we
describe a theory that connects hardware (neurons and muscles with inherent
severe speed-accuracy tradeoffs) with system level control to explain Fitts'
Law for reaching and related laws. The results supporting the theory show that
diversity between hardware components is exploited to achieve both fast and
accurate control performance despite slow or inaccurate hardware. Such
"diversity-enabled sweet spots" (DESSs) are ubiquitous in biology and
technology, and explain why large heterogeneities exist in biological and
technical components and how both engineers and natural selection routinely
evolve fast and accurate systems using imperfect hardware.
