User blog comment:CreatorTheta/Human Evolution Theory in RWBY/@comment-76.184.72.145-20140625065049

Superspeed could also be related to the nervous system. It's possible for people to react at a faster rate than normal with the right stimuli-if you burn your hand, you pull back your hand without thinking about it. If they have special areas of the brain that we don't, like a "reflex center" connected to their senses to recognize dangerous combinations of shapes and movement, such as a sharp claw swinging towards them. There's also reports of times when people see everything slow down, or people reacting exceedingly well, which could be related to "muscle memory." If they've got better muscle memory, they can learn to respond to things faster, and to a greater degree than normal.