1.   Aging also affects light-sensing cells called rods and cones in the retina, the tissue in the back of the eye.

2.   Of course, aging does not affect all people in the same way, a fact that is interesting to scientists because variability speaks against inevitability.

3.   Weight lifting, rowing and wrestling all require short bursts of great strength, the ability least affected by aging.

4.   Many of the genes affected by aging are those that help the body rid itself of oxygen radicals, chemicals produced during the process of metabolizing calories in cells.