Scientific Evidence-Based Mechanisms of Acupuncture

Activating chain reactions in both local tissues and the CNS
Local skin reaction and cutaneous micro-current mechanism
Local interactions between the needle and the surrounding soft tissues
Local relaxation of muscle shortening and contracture
Neural mechanisms
Blood coagulation and lymphatic circulation
Local immune response
DNA synthesis to replace injured tissues and repair the acupuncture lesions

The fMRI shows activated visual regions in the brain when an acupuncture point is stimulated on the lower leg. The point is called "Bright Light" which is supposed to brighten the eyes.

The above findings are only partial evidences that we might understand so far. If history is more dependable than science, acupuncture is something beyond science.