Does menstrual blood really attract bears? Why does blood look blue in your veins? And why were the first blood transfusions performed with animals? Here are 15 facts, historical and biological, you probably didn't know about blood.
He was found with an arrow in his shoulder and a stab wound in his hand, but when Ötzi the Iceman was first discovered in 1991, scientists were unable to recover so much as a drop of blood from his otherwise intact body.