Digits Descend From Cloaca: Evolution’s Weird API Call

In a jaw-droppingly blunt biology nugget, scientists have pinned down that ā€˜making digits’—those nimble fingers and toes we love stubbing on furniture—involves gene activity originally reserved for a cloaca. Yes, the multi-purpose orifice present in birds, reptiles, amphibians, and some mammals. Gone are the days when digits just showed up like a simple software update; apparently, evolution dug deep into its weird ancestral toolbox, rummaged around the cloaca drawer, and coded your fingers with borrowed leftovers. This makes us all a bit unsettlingly connected to the biology lesson you skipped in school. Who knew the secret to your thumbs was previously managing, well, everything?

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Source: Arstechnica | Published: 9/17/2025 | Author: John Timmer