Carrion crows can tell the difference between geometric shapes (Credit: Christine Matthews / CC-BY-SA-2.0/ Wikipedia Commons)

Crows are remarkably smart animals, with thinking skills comparable to those of five- to seven-year-old children. They can solve puzzles, use tools, and even remember faces. Now, researchers at the University of Tübingen in Germany have found that these unassuming birds can also recognize different geometric shapes — a skill previously seen only in humans.