[GauntletWizard]

Pure wild speculation: I suspect that an awful log of our biological form is fractals formed from chemical gradients, with our DNA controlling the amounts of each chemical, both how fast they're produced and consumed. Included in this are some wild "Programs" were Chemical A causes Chemical B to be produced, Chemical B produces Chemical C and chemical C shuts off chemical A - In wild patterns that eventually form the beauty of our bodies. On a mass scale, with dozens of signaling chemicals and switches flipped - Organelle A produces chemical B and C and they osmose. B spreads far and wide, and an organ grows wherever B is concentrated. C doesn't spread, and eventually it grows concentrated enough to shut itself off. Thus, the physical limits of a body are formed.

Fingerprints would then be where this all happens on a micro scale - Running the game of life in 3d on the cells of your body, until they reach an "end state" of a stable limit of your skin.

[lurquer]

Turing’s diffusion/reaction algorithm involved this. As you intuited, it is a good system for making fractal-like designs and patterns. Cheetah spots, zebra stripes, maybe even 3D structures like capillaries...

But, such a system can’t make discrete forms—like a nose.

There’s something else going on.

For instance... deer grow antlers every season (antlers are not horns; rather, they are complex structures with tissue, bone, skin, nerves, etc) Anyway, if a growing antler is nicked, scar tissue will form... no big deal, right? But, this is where it gets weird... When the antlers fall off and then grow the following year, the scar will be present on the new antlers. Let that sink in.

[selimthegrim]

It may be a way for deer especially with high status to recognize each other. Also marks of trauma or injury often persist in human nailbeds.

[causi]

Not that such a thing is impossible with epigenetics, but do you have a source for that?

[Retric]

There are several parts embryo development that does operate on chemical gradients especially the initial stages. But like most of biology it gets really complex and isn’t limited to any one approach.

For example as you gain fat tissue you need to increase the number of capillaries feeding that tissue, which in tern needs to link up to arterioles and arteries on one side and veins on the other. https://www.ncbi.nlm.nih.gov/books/NBK53238/ This happens well into adulthood.

[nvrspyx]

You might be interested in reading up on homeobox genes.

https://en.m.wikipedia.org/wiki/Homeobox