DNA is not the only map

A planarian flatworm is cut in half. It grows a head. Change a voltage picture first — the pattern of electrical charge across the remaining tissue — and the same worm, with the same DNA, grows two heads. Sometimes that two-headed target stays, cut after cut, after the original stimulus is gone.

Bioelectricity here is not a nerve spark and not a metaphor. It is voltage shared between cells through tiny tunnels. Genes build the pumps and channels (the hardware). The pattern they settle into can work like software: a map of the body the group is trying to become. Hardware can stay. Software can be rewritten. A liver that stops at the right size is a stop-rule. A tumor that should have stayed a tissue is a stop-rule that failed.

David Sinclair pointed at this work because aging, on that view, is not only worn parts. It is a map that has drifted — information that no longer says when to stop.

You do not need a protocol. You need the category: some repairs will be conversations with a map, not edits to a text.

The tempting mistake is to say that if the sequence did not change, nothing important changed. The two-headed worm is the counter-example.

That is what lets you look at a new body made of old frog DNA and not call it a miracle.