Look at the palm of your hand

From "Being Mortal" by Atul Gawande, p. 30-31.

"You can see all these processes [of aging] play out just in the hand; 40% of the muscle mass of the hand is in the thenar muscles, the muscles of the thumb, and if you look carefully at the palm of an older person, at the base of the thumb, you will notice that the musculature is not bulging but flat. In a plain X-ray, you will see speckles of calcification in the arteries and translucency of the bones, which, from age 50, lose their density at a rate of nearly 1% per year.... The hand has 29 joints, each of which is prone to destruction from osteoarthritis, and this will give the joint surfaces a ragged, worn appearance. The joint space collapses. You can see bone touching bone. What the person feels is swelling around the joints, reduced range of motion of the wrist, diminished grip, and pain. The hand also has 48 named nerve branches. Deterioration of the cutaneous mechanoreceptors of the pads of the fingers produces loss of sensitivity to touch. Loss of motor neurons produces loss of dexterity. Handwriting degrades. Hand speed and vibration sense decline. Using a standard mobile phone, with its tiny buttons and touch screen display, becomes increasingly unmanageable." 

Yup. So when an elder can't open a pill bottle or is slow pulling out her ID, remember, in a few years it will be you. Now go look at your palm.  I wonder if typing on phones with thumbs will lessen the viability of the thenar muscles for today's millennials?