In the left femur, the left thigh bone, there's another one.

Two weeks after my diagnosis, a biopsy confirmed I had a seven inch osteosarcoma in my left femur.

And then I had a 15 hour surgery in which my surgeon, Dr. John Healey at Memorial Sloan Kettering Hospital in New York, took out my left femur and replaced it with titanium.

I broke my left femur that day it's the largest bone in your body and spent the next two months in a body cast that went from my chin to the tip of my toe to my right knee, and a steel bar went from my right knee to my left ankle.

Because a DNA sequence is a one dimensional entity, it lends itself much better to single number comparisons than a four dimensional body does. The genes that lead to the production of the human and chimpanzee femur may be 98 99 identical, but it is impossible to say whether the bones themselves are more or less similar than that.