About the Book: You: A Natural History
What are you? Obviously, you are a person with human ancestors that can be
plotted on a family tree, but you have other identities as well. According to
evolutionary biologists, for example, you are a member of the species Homo
sapiens. To a microbiologist, though, you are a collection of cells, each of
which has its own cellular ancestry. A geneticist might point out that besides
these identities, you can be understood as a gene-replication machine, which can
be plotted on a "genetic tree." Finally a physicist will give a rather different
answer to the identity question: you