"This article doesn’t mince words: Fish buttholes may be the reason we now have fingers, (ScienceAlert, 22 September 2025).
That’s right — a new Nature paper, Co-option of an ancestral cloacal regulatory landscape during digit evolution, (Nature, 17 September 2025), claims our digits – fingers and toes – arose when evolution “co-opted” regulatory DNA originally used in the cloaca, the common outlet for waste and reproduction in many animals.
If you think that sounds like evolutionary storytelling with a potty-mouth twist, you’re not wrong. But the real story here isn’t cloacas or fingers.
--It’s how evolutionary theory itself keeps recycling ideas — discarding them as discredited one decade, reviving them under a new name the next, and calling the process “progress” in an endless Hegelian loop.
The Study Behind the Hype:
The team reporting in the Nature article, summarized in From fish cloaca to fingers: Scientists trace the origin of our digits, (Phys.org, September 17, 2025), worked with zebrafish, testing a conserved stretch of noncoding DNA near the HoxD cluster, the master “architect genes” of development.
The Study Behind the Hype:
The team reporting in the Nature article, summarized in From fish cloaca to fingers: Scientists trace the origin of our digits, (Phys.org, September 17, 2025), worked with zebrafish, testing a conserved stretch of noncoding DNA near the HoxD cluster, the master “architect genes” of development.
When they deleted this region, gene activity faltered in the cloaca of the zebrafish, but not in the fins. From this, they concluded that the same regulatory landscape was later “co-opted” to help pattern digits in land animals.
This surprising result suggests that the cloaca—an organ where the intestinal, excretory, and reproductive systems meet at their extremities in many species—has been reused in terrestrial vertebrates to develop digits.
So instead of inventing a new system for fingers, nature allegedly “rewired” an old one."
This surprising result suggests that the cloaca—an organ where the intestinal, excretory, and reproductive systems meet at their extremities in many species—has been reused in terrestrial vertebrates to develop digits.
So instead of inventing a new system for fingers, nature allegedly “rewired” an old one."
CEH