Science today isn't the same as the science 2000 years ago was but some principles remain the same. The human knowledge constantly grows but with more knowledge there comes even more mysteries and unsolved questions, so science is always going forward.
Causes. The most common cause of a cervical herniated nucleus pulposus is gradual degeneration of the disc, attenuation (weakening) of the posterior annulus fibrosis, and subsequent protrusion of the nucleus pulposus into the spinal canal causing compression of the nerve root.
Such is the aging process of the spine. A herniated disc causes problems in two ways. First, the material that has ruptured into the spinal canal from the nucleus pulposus can cause pressure on the nerves in the spinal canal.