New evidence shows that earth's climate can change dramatically in only a decade. Could greenhouse gases flip that switch?
A discovery that could revolutionize medicine raises the question of where to draw the line on human embryonic research
Pleasure or pain? Social response or reflex? Tickling and the laughter it induces are an enigmatic aspect of our primate heritage
The asymmetry of the amino acid molecules found in all living things may have originated in space billions of years ago
No longer limited to warding against infectious agents, vaccines may help treat diseases after they have been diagnosed