Mandira Nayar interviews Siddhartha Mukherjee in The Week:
Q\ You deal with a metaphysical question in the book, about new humans.
A\ That is the provocative idea in this book. The new human is not going to be a kind of science fictional character. We are already making new humans. The first time someone transfused blood into another person, they imagined very believably that the person would be a different human being. The first time bone marrow transplants were done, there were real philosophical questions raised: are you the same person?
On a very fundamental level, we are dealing with these questions today as we move more and more into cell and gene therapies, where we are replacing cells, changing cells, and ultimately, trying to create a chimera of humans, other parts added to them, etc. I felt that the provocative question I would ask is, why aren’t these new humans? Everyone talks about new humans in a kind of sci-fi way, as if we were going to become robots. But the more likely course [is] to find ourselves rebuilt, or rebuilding ourselves by adding and subtracting cells, making cells different from ourselves through genetic therapies. These are humans that have been fundamentally changed. Whether you put a new kidney in me, whether you put a new layer of skin on me, whether you change my knees―some of these are cellular, some of these may not be cellular. But cellular therapy is creating a kind of a human being that we haven’t encountered before―often in which one human’s body fuses with another’s.
More here.