From fruit flies to whales, virtually every animal sleeps. But why? Why do we need to spend nearly a third of our lives in such a defenseless state? Scientists are peering more deeply into the sleeping brain than ever before, discovering just how powerful sleep can be, playing a role in everything from memory retention and emotional regulation to removing waste from our brains.
We can now edit the human genome with a tool called CRISPR. But how far should we go?
Can bringing predators—and fear—back into an ecosystem help restore its natural balance?
Follow eagles from the nest to the skies to see what makes these predators so remarkable.
