This is SCIENCE FRIDAY, I'm Ira Flatow. He's been called Mayor McSchwinn for riding his bicycle to work. He's pledged to turn his town of Seattle into a model for what one city can do to lower its carbon footprint, and for good reason. As the climate changes, coastal cities like Seattle are challenged by rising sea levels.
Look through a series of 15th-century woodcuts, and you'll find that the leper is as much an icon of medieval art as the crown or the cross.
Leprosy was so common in Europe during the Middle Ages that it's estimated 1 in 30 people was infected with the bacteria. But by the turn of the 16th century, after the Crusades had swept across Europe, the disease mysteriously disappeared. And it never returned.
This left scientists puzzled. Did the bacteria mutate to become less harmful, or did Europeans become resistant to the germs?
We've all seen a flock of birds shift direction instantaneously mid-flight, or a school of fish swirl in what looked like tightly choreographed maneuvers. That's called collective behavior and it fascinated and baffled scientists. Why do they do it? How? Telepathy? Now technology is revolutionizing the way researchers can track, visualize and even create swarms, and what they're finding will make you go wow.