am I me?"
This question was asked by my eight-year-old grandson George. In eight
letters it summarizes the conundrum of personal existence in an impersonal
universe. How does it happen that a couple of liters of grey matter
organizes itself into the unique stream of self-awareness that calls
itself George? If we could answer this question, we would be on the
way toward an understanding of brain structure and function at a deep
level. We would probably have in our hands the key to a more rational
and discriminating treatment of mental illnesses. We might also have
the key to the design of a genuine artificial intelligence.
Every human being must have asked this question in one way or another.
For most of us, the question expresses only a general philosophical
curiosity about our place in the order of nature. But for George the
question has a more specific technical meaning. He has an identical
twin brother Donald, and he understands the distinction between monozygotic
and fraternal twins. He knows that he and Donald not only have the same
genes but also have the same environment and upbringing. When George
asks the question, he is asking how it happens that two people with
identical genes and identical nurture are nevertheless different. What
are the non-genetic and non-environmental processes in the brain that
cause George to be George and cause Donald to be Donald? If we could
answer this question, we would have a powerful new tool for the investigation
of cognitive development. The conventional wisdom says that mental differences
between George and Donald arise from local randomness of neural connections,
undetermined either by genes or by sensory input. But to say that the
connections are random only means that we do not yet understand how
they came about.
Dyson is professor of physics at the Institute for Advanced
Study and author of The Sun, the Genome, and the Internet.