The latest issue of the scientific journal Nature has a report on ‘ smart mice ’ that have certain genetic manipulation to enhance some brain functions. Compared to normal ones, these manipulated mice show better performance in a variety of standard tests. For example, it takes fewer trials for them to find the floating platform when swimming in a body of water (the water maze), or they are able to find their way through a more complicated labyrinth in a shorter time. However these advantages do come with some trade-offs. The mice that perform better in a complicated labyrinth perform less well in a simpler labyrinth than normal mice, and one of the manipulated genes in another type of smart mice is often involved in cancer development. (If you cannot read the article online, please ask me for a pdf copy.) Of course the scientists hope to learn something from the mice to advance treatments for neurological disorders or enhance mental functions. But before they can reach meaningful and