Scientists have struggled for centuries to pinpoint the qualities that separate human beings ... by the NOVA Science Trust, the Corporation for Public Broadcasting, and PBS viewers.

Originally appeared on the NOVA Web site Cut to the Heart. Let's get straight to the heart of the matter—the heart's job is to move blood. Day and night, the muscles of your heart contract and ...

Subjects/Skills: STEM; Matter and Its Interactions; Motion & Stability; Energy, Waves & Information Transfer; Ecosystems; Heredity; Biological Evolution; From Molecules to Organisms; Earth’s Place in ...