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Origin of the phyla and cancer



John M. Saul [], ORYX, 3 rue Bourdaloue, F-79009 Paris, France.


Multicelled animals with specialized cells (metazoans) emerged shortly after rising oxygen levels in the seas permitted formation of collagen-family molecules. Certain unicells then formed 3-D clusters, some with disc- or ball-like shapes that happened to resemble blastulas. These became unstable beyond a certain size due to contrasting metabolic styles among their component cells. For whereas cells near their exteriors could employ oxygen respiration, cells closer to the oxygen-deprived interiors were obliged to rely on anaerobic metabolism (fermentation), a process that produces waste molecules that, if retained within cells, cause disproportionate cell growth. Unstable blastula-like forms would either disintegrate or reorganize along surfaces of relative weakness in a process that may be likened to gastrulation. Initial cell-differentiation depended on the quantity and diversity of retained fermentation products and on the pumping of molecules from cell to cell by the consequent electro-chemical gradients. In subsequent contexts, oxygen deprivation, fermentation, excess cell growth, and disintegration or reorganization of tissues produce cancer.