Language might have evolved from hand gestures, say researchers who study communication in chimpanzees. (p. 275)

The oldest rocks in the world show that Earth's shifting crust began its tectonic movements almost 4 billion years ago. (p. 179)

A "carpet" of microscopic filaments sprayed onto a surface can prevent it from reflecting light, a potentially useful trait for technologies from solar cells to fiber-optic communications. (p. 132)

A new artificial knee ligament that sparks regeneration of natural tissue could eventually make recovering from knee-repair surgery less painful and debilitating. (p. 116)

Evidence from ancient dunes points to three periods of prolonged drought in the U.S. Great Plains, but finding their causes may be more complex than previously supposed. (p. 84)