The natural evolution of disc disease and degeneration leads to stiffening of the intervertebral joint. This leads to osteophyte formation—a bony overgrowth about the joint. This process is called spondylosis, and is part of the normal aging of the spine. This has been seen in studies of normal and diseased spines. Degenerative changes begin to occur without symptoms as early as age 25–30 years. Not uncommonly, people experience at least one severe case of low back pain by the age of 35. This can be expected to improve and become less prevalent as the individual develops osteophyte formation around the discs.