  A novel theory for cell differentiation is proposed, based on simulations
with interacting artificial cells which have metabolic networks within, and
divide into two when the final product is accumulated. Results of simulations
with coupled chemical networks and division process lead to the following
scenario of the differentiation: Up to some numbers of cells, divisions bring
about almost identical cells with synchronized metabolic oscillations. As the
number is increased the oscillations lose the synchrony, leading to groups of
cells with different phases of oscillations. At later stage this
differentiation is fixed in time, and cells spilt into groups with different
chemical constituents spontaneously, which are transmitted to daughter cells by
cell divisions. Hierarchical differentiation, origin of stem cells, and
anomalous differentiation by transplantations are also discussed with relevance
to real biological experimental results. (Keywords: differentiation, metabolic
network, cell division, clustering, open chaos)
