In the book by P.D. James I just read, Adam Dalgliesh lifted the hands of the victim. The right hand was stained red with blood, from gripping the handle of the knife with which her throath had been slit. Dalgliesh let his fingers slide gently along hers. His conclusion was that she was murdered, by someone who did not know she was left-handed. Why? She had a small callus on her left middle finger, from writing.
I know I have this thickening of the right middle finger, betraying that I write with my right hand - it's not really callused, just the first joint being slightly thicker than on the left hand. I wonder if this will change in the future? Will there perhaps be a slight thickening of the first joint of the right thumb, from hitting the space-bar? Will the muscles of the right arm, the ones that control the right middle finger, be more developed from controlling the mouse or joystick? What will the Dalgliesh of the future look for before he can rise from examining the victim, to say, in his calm, polite manner "she was murdered"?