A female house mouse closely sniffs a male's urine scent mark to detect the protein sex
pheromone darcin, which induces her to remember the location of the male's scent. The owner of
the scent mark is just visible out of focus in the background. This image relates to a paper that appeared in the Dec. 14, 2012, issue of Science, published by AAAS. The paper, by Sarah Roberts at University of Liverpool, Leahurst Campus in Neston, UK, and colleagues was titled, "Pheromonal Induction of Spatial Learning in Mice."