“I’ve been asked a lot if I threw in my own experiments,” says Milks. “But that wouldn’t tell us anything, other than that I’m a bad thrower.” Instead, she gave the spears to six trained javelin-throwers, whom she filmed with high-speed cameras. The participants hurled the spears both far and fast. It’s sometimes said that heavy spears would slow mid-flight and hit their targets with dull thuds. But Milks found that the replicas slowed very little, and landed with a kinetic wallop comparable to projectiles launched by bows or spear-throwing tools.