> The premise is that total DNA is the same for all cells in the same
> animal and from one mammal to the other. Lower forms of life have less
> DNA. As some mammals become more complex than others in one area or
> another, the % of DNA devoted to that specialization is greater. This
> leaves a deficit of DNA for other tasks (because total DNA is
> constant). Nutrient synthesis is the expression of one of DNA's tasks.
> If nutrients can be obtained from food and not synthsized, then
> valuable DNA space is saved.

That's interesting, but I wonder if there is any evidence that there is
a lack of space in our DNA. Isn't it possible that our DNA, like our
brain, can still store much more information? [We also know that
some genes are repeated thousands of times]

And the fact that the animals don't synthetize such or such nutrient
doesn't mean that the gene is lost. In fact, many genes still exist
but are not expressed anymore [hens still have genes to build teeth!]

Best wishes,

Jean-Louis