alt Hacker NewsAn example of the contrary:
Your eyes would be misplaced if the process from cell clump to mat to tubule failed due to chemical signaling failure, but the whole embryo tends to be spontaneously aborted when gestation fails so catastrophically.
And despite genitalia being roughly one of two forms and similarly positioned, chemical signals can disrupt their formation.
> How does that happen if the chemical signals, cell machinary, and electrical signals aren't determined, even if indirectly, by DNA?
They don’t produce the same results with perfect accuracy — 75% of pregnancies are spontaneously aborted, at least in part due to developmental failures.
But the problem with this argument is simple: you have a human cell everywhere you have human DNA, so those correlations with DNA are also correlations with cellular machinery and with particular chemical signals from the mother. There was no point in those 200,000 years where DNA operated independently of those other mechanisms — we can only say the system as a whole reliably creates those features.
Interesting points, especially about the challenge of correlation. I guess we could remove DNA and see what happens ...
Somehow the machinary is passed down: Do we know of another mechanism besides DNA that is self-perpetuating? Is there any living creature without it? Prokaryotes (bacteria) even have DNA.
Or is there a way to do it without self-perpetuating mechanisms? Is that logically possible? Some machinary might be perpetuated by other machinary, e.g. the chemical might recreate the electrical, meaning it's not self-perpetuating. But that's not different than DNA: DNA itself isn't the machinary, but its self-perpetuation is what recreates other parts.
I suppose some parts of the environment are consistent, such as sunlight, air, water, and heat, but the environmental stimuli must trigger something that is already there.