http://abcnews.go.com/Health/girl-ages-unravel-secret-eternal-youth/story?id=19974247

8-Year-Old Never Ages, Could Reveal 'Biological Immortality'

Gabby has a mysterious condition, shared by only a handful of others in the world, that slows her rate of aging.

Walker explains that physiological change, or what he calls "developmental inertia," is essential for human growth. Maturation occurs after reproduction.

"Without that process we never develop," he said. "When we develop, all the pieces of our body come together and change and are coordinated. Otherwise, there would be chaos."

But, said Walker, the body does not have a "stop switch" for this development. "What happens is we become mature at age 20 and continue to change."

The first subtle internal body changes of aging are seen in the 30s and become more visible in the 40s.

"There is a progressive erosion of internal order as a result of developmental inertia," he said.

"If we could identify the gene and then at young adulthood we could silence the expression of developmental inertia, find an off-switch, when you do that, there is perfect homeostasis and you are biologically immortal."

Now Walker doesn't mean that people will never die. Disease and accidents will still end human life.