These are excerpts and elaborations from my book "The Nature of Consciousness"
Differentiation Genes, obviously, do not
carry all the information needed for an organism to develop. How do cells of many
different kinds come to occupy the "right" position in space? How do
brain cells grow in the brain rather than, say, below the armpit? The
phenomenon is even more mysterious because we now know that the early embryos
of many animals, from insects to mammals, exhibit the same spatial pattern of
activity of the same group of genes, before a morphological structure is
created. A body is shaped by the
orderly movement of billions of cells to the locations that specify their role.
Cells are not genetically programmed to perform a specific role, but during
development they become specialist. It appears that what a cell will do for the
rest of its life depends on where its journey ends. "Growth" is this
mass migration of cells towards an unknown destination that will determine
their future. "Pattern
formation" is the mechanism by which cells in different parts of a
developing organism acquire different fates. “Pattern formation” constitutes
the main concern of Developmental Biology. Today, we believe that an organism
is made from a very large number of autonomous cells which can interact among
each other and that the whole functional organism "emerges" (i.e.,
arises) from local interaction of cells. Little is known about
the physical process that allows this
to happen, but cells in the embryo appear to be able to regulate their adhesion
to surfaces and to other cells and they appear to do this to change shape or
move. Back to the beginning of the chapter "The Physics Of Life" | Back to the index of all chapters |
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