alt Hacker News> I don’t believe genetics ever claimed to provide a theory of why eyes grow where eyes grow.
That’s the whole point of developmental biology, to show how features of the human body form and develop based on gene expression, the timing of which during embryonic and fetal development itself is dictated by your genes.
If not your genes, what else would determine why you have eyes in about the same place in your head as every other human?
> The cells in your eyes have exactly the same DNA as the cells in your big toe, so developmental morphology cannot be explained with DNA alone.
Sure it can, because while every cell has essentially the same DNA, the expression of genes differs between cells, which is what causes cells to differentiate. And this differentiation also controls development; look up the Hox genes as an example.
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> If not your genes, what else would determine why you have eyes in about the same place in your head as every other human?
Theoretically, it could be second or much higher order effects that result from genes. It could be a combination of complex factors - the environment in the womb, nutrition, behavior by the mother, etc. - that eventually trace back to DNA.
Also, is it literally true that DNA is the only thing that's consistent (in these respects) between all generations of Homo sapiens?
Your last paragraph is their point: genes are regulated to produce that effect. The genes themselves aren’t doing it, but eg diffusion of chemical signals to inactivate genes.
Morphology is determined by the combination of genes, chemical signals, original cell machinery, and apparently electrical signals. But we never believed that genes determined morphology alone, eg, we know that chemical signals can cause anomalies.
He's changed wild-type planarians to grow the heads of other species. It reverts after a few weeks, because the system has error-correcting mechanisms, but the DNA of these worms is unchanged.
He once compared tinkering with DNA as pulling out a soldering iron to fix a software bug.
In the case of morphology, DNA may not be the best level of abstraction. It's certainly possible, just as one can use chemistry for social problems, but for some problems, affecting cell-to-cell communication may be a more direct path.