From Ruth Williams at The Scientist:
Two studies in Science today (December 7)—one that focuses on prenatal development in humans, the other on infancy to old age—provide insights into the extent of DNA sequence errors that the average human brain cell accumulates over a lifetime. Together, they reveal that mutations become more common as fetuses develop, and over a lifetime a person may rack up more than 2,000 mutations per cell.
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Within the now burgeoning field of somatic mutation analyses, the brain is a particular area of interest. That’s because unlike organs such as the skin and gut where cells are replaced daily, the brain’s neurons, once established in the fetus, for the most part stick around for life. Somatic mutations in these cells, then, could affect brain function, behavior, and the propensity for disease long-term. Indeed, it’s thought that such mutations could influence the development of diseases such as schizophrenia, autism, and Tourette’s, which have unclear etiologies, says Yale School of Medicine’s Flora Vaccarino who authored one of the studies. More.
This may seem like an inappropriately philosophical question but is it really the same cell after 2000 mutations? If it were a piece of property, we would say it has the same address, no matter what else happened in the location. But will that work for cells? What makes it the same cell? The location? The membrane? The historical record of mutations?
That matters because we can ask the same about ourselves: Are we really the “same person” as we were when we were four years old? In what sense? That is where we need concept from information theory, not theories of matter and energy.
See also: New Scientist: Was it a huge dose of dopamine that made us so smart? Naturalist ideology requires something like extra dopamine production to be seen as a cause, not an effect. Of course, what we are really talking about is human consciousness, whose origin no one understands. And whatta feast of just-so science!
and
Boy can see without primary visual cortex of brain