The past three years or so have brought more and more of my attention to my thumbs. Why? Because their worn-out joints complain many times a day. And I can’t blame them for weakening and hurting. Look at all they’ve done for me, for three quarters of a century! Lifting, carrying, pushing, pulling. Squeezing, twisting, opening, closing. Pouring, filling, shaking, emptying. Typing, cutting, hammering, sewing. Digging, throwing, swinging, catching. Measuring, gesturing,