Toward a Biology Worthy of Life > Genes and the Central Fallacy of Evolutionary Theory > Brief excerpt
A project by Stephen L. Talbott

The organism as agent of its own development (4)

The vast majority of cells in the body at all stages of development have (more or less exactly) the same DNA sequence. Yet the path from the singular zygote through the many stages of cell differentiation to a particular mature cell type is a path that, for every such type, takes a novel course. Each path of differentiation represents a distinct cellular “evolution”, or active unfolding of potential. ...

So the same DNA sequence sits contentedly within the unique phenotypes of hundreds or thousands of mature cell types. Some of these are as visibly and functionally different, in their own way, as the phenotypes of any two organisms known to the evolutionary biologist. And in order to reach these mature phenotypes, this DNA must have yielded itself to the finely choreographed yet flexible and adaptive sequence of transformations along each cellular path of differentiation — transformations that are “remembered” (inherited) from one cell generation to the next, yet take their place within a smooth trajectory of change.

Who, in light of all this, will dare to claim: the numerous divergent pathways from the zygote to the various cell types of the body are explained by the one thing in the cells that remains more or less the same, namely, the bare DNA sequence, unstructured by the organism’s developmental processes?

Moreover, once the “end point” of differentiation of a particular cell lineage is reached, the recognizable character of that cell type can be maintained indefinitely throughout the life of the organism and through all subsequent cell divisions. Or, in some cases, it can be changed further at need. Or, as with neurons and lens fibers, a cell can remain itself without further division over the several decades of a human life.

The power of the cell to remain itself in any one of many radically different configurations signifying radically different activities and conditions, has no particular temporal limit. Both this stable character and the power of differentiation during development are guaranteed only by the qualities of the cell as a whole in its organismal context, rather than by a fixed sequence of nucleic acids. And (looking ahead) it is just such a whole cell that passes from one generation to the next.

All these truths of development have yet to be taken with due seriousness by students of evolution. The individual organism expresses itself with almost incomprehensible eloquence, insistent aim, and aesthetic sensibility as it passes through the integral stages of unified metamorphosis or transformation — transformation involving much more than DNA. Yet this organism is somehow supposed to be rendered mute and directionless when engaged in the intricate, creative processes through which it contributes dynamic potentials to its offspring and shapes a space for their lives.

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