05/22/2013 01:15 pm ET Updated Jul 22, 2013

Dare to Be 100: Nature, Nurture, or Both?

Every Wednesday morning is like Christmas. I waken to see whether my Santa postman will deliver my weekly copy of Science. This journal is the preeminent scientific publication in the world. I am addicted to it. It is my dependable natural high.

This week, for example, it included an article, "Why Adults Need New Brain Cells." Now maybe I am naïve, but shouldn't everyone be fascinated by this topic? Or am I strange? My enthusiasm for it was confirmed by the fact that the May 20 issue contained within it this accompanying perspective, written by scientists from the Karolinska Institute in Stockholm. It in turn was a response to another paper in the journal by workers from Germany. Their fundamental research involved a study of 40 genetically identical mice that were collectively raised in an enriched environment constructed in such a way as to encourage spontaneous activity. These mice were fitted with electronic collars that precisely measured their exploratory behavior.

After three months of this closely-monitored existence, they were sacrificed, and their brains were scrupulously examined. This revealed that the hippocampal portion of the brain showed much evidence of new brain cell growth. These results showed conclusively that the animals who ran more also grew their brain more.

This is in accord with other recent information indicating that a brain growth factor, BDNF -- brain-derived neurotrophic factor -- was also shown to be reactive to exercise pattern. Someone posited that BDNF is like Miracle-Gro for the brain.

So maybe when I am doing my jogging I am inadvertently growing my brain.

New exploratory behavior is now added to the list of benefits provided to nature by our individual nurture. "Don't slow down" seems to be the message. The accompanying editorial suggests that "the way we live makes us who we are."

I am a student of the Serenity Prayer, which teaches, "Change what you can, accept what you must, but know the difference." I like the idea that most of this option is up to us. Among my life choices, I choose to be active. Age does not disqualify me from this imperative.

For more by Walter M. Bortz II, M.D., click here.

For more on personal health, click here.