The Why Files asks why mass killers pull the trigger. What are the warning signs of “rampage” shootings? Can they be prevented?

Study finds that male body odor is harder to mask, but the male nose is more easily confused. Info lends insight into human mating, and helps perfume makers. So what’s in your deodorant?

New video captures AIDS moving inside immune cells: HIV enters pods that form on the surface, then jumps across into a healthy immune cell that is now doomed to spread HIV — and die.

Last week, Pres. Obama revoked the limits on studies of cells that can become any body cell. What was lost in eight years of limits on embryonic stem cells? What’s ahead?

We explore the sad saga of pet primates. Are these pets psychologically good for us? For them? Are humans and other primates trading diseases at home, and in the wild?

Disgust caused by filthy food, feces, and an unfair deal all trigger the same facial expression. So is our moral disgust the same as the primitive disgust caused by toxic food?

Researchers in positive psychology find that giving is better than receiving, that social relationships are key, and that money can – in some circumstances – buy some happiness.

Happy Thanksgiving! We celebrate eating — and food. Hungry: Is that your “food clock” ringing? Why does a fruitfly need to smell? How does bitter taste to you? And could eating MSG make you fat?

Study finds that holding a warm cup of coffee for a few seconds can make us see other people as warmer, more outgoing. How come?

A single neuron in the brain may deliver enough information to control a muscle. These results could eventually help bypass the spinal cord, allowing paralyzed people to control their own muscles.