People have been reading other people by look at their eyes since the dawn of human kind. The important fact is that some are better at it than others. Then there those who are exceptional at it. They have used their skills of reading people through their eyes to advance their respective causes. But they cannot share this kind of knowledge with others because it is too abstract to be taught.
Now if we can create data set that not only big enough to encompass it all, then we can have algorithm that can not only deduce but actually evolve from that point. It's a scary thought.