Fruit flies with a new variant of a 'clock gene' are spreading northwards. Neurobiologists have now found an explanation for this phenomenon. Evolution takes place constantly, everywhere in nature.

If you are in need of instant energy before physical activity, it's best to avoid sugary candy bars. Instead, try one of these foods that delivers immediate energy right before your physical activity.

Cynthia Sass is a nutritionist and registered dietitian with master's degrees in both nutrition science and public health. Frequently seen on national TV, she's Health's contributing nutrition editor ...