The title of Emily Singer’s article made me suspicious at once (“Intelligence Explained,” November-December 2009). As the first few paragraphs demonstrated, I was right. The new research she writes about “may explain, at least in part, the variations in human intelligence.” Intelligence as such is a different matter, of course. The brunt of Singer’s argument is that new imaging technologies allow more detailed study of the brain’s structure. Not only neurons in the gray matter, but also the neural fibers that connect them in the white matter, can now be seen as strands of spaghetti. But it is enough to remember some basics of brain science to see how distant is the dream of understanding variations in human intelligence. The number of neurons in a brain is estimated to be somewhere between three-hundred billion and a trillion. Even the lower estimate is about the same as the number of stars in our galaxy, the Milky Way. When multiple endings of neural fibers are added, the complexity of the structure is staggering. To wit, explaining intelligence will take a while. A good title, though.