Angelo Mosso's "human circulation balance" machine worked like a seesaw to measure blood flow changes to the brain. Stefano Sandrone et al., Brain hide caption

itoggle caption Stefano Sandrone et al., Brain

"As the boundaries of what we determine as the safety zone grow ever smaller, we cut off our children from valuable opportunities to learn how to interact with the world around them." — Gever Tulley TED hide caption

itoggle caption TED