{"id":88,"date":"2025-09-23T23:30:00","date_gmt":"2025-09-23T23:30:00","guid":{"rendered":"https:\/\/good-worldwide.go-vip.net\/upworthy\/2025\/09\/23\/fish-buttholes-human-fingers\/"},"modified":"2025-09-23T23:30:00","modified_gmt":"2025-09-23T23:30:00","slug":"fish-buttholes-human-fingers","status":"publish","type":"post","link":"https:\/\/goodinc.com\/qa-upworthy\/2025\/09\/23\/fish-buttholes-human-fingers\/","title":{"rendered":"New study ties the ‘buttholes’ of fish to the evolution of human fingers"},"content":{"rendered":"

We\u2019re all familiar with the viral obsession<\/u><\/a> of cat buttholes<\/u><\/a>, but after this story, fish<\/u><\/a> buttholes might be the next new thing. <\/p>\n

We already knew that digits, aka fingers, evolved from genetic programs present in fish, considering all vertebrates<\/u><\/a> can be traced back to an aquatic ancestor (cue mermaid theories). <\/p>\n

However, until now, just how digits evolved from our deep sea brethren remained a mystery. Thanks to a recent study<\/u><\/a> published in Nature<\/a><\/em> from research teams across the globe\u2014including Geneva, France, Massachusetts, and Chicago\u2014we\u2019ve learned that they likely evolved not from fins, as many experts suspected, but from the fish\u2019s cloaca. <\/p>\n

\n

\"fish
Even fish can hardly believe it. media2.giphy.com<\/a><\/figcaption><\/figure>\n

<\/p>\n

Wondering what a cloaca is? You\u2019ve come to the right place! <\/p>\n

For many vertebrates, including reptiles, birds, amphibians, and fish, the cloaca serves as a single opening for the digestive, urinary, and reproductive systems. Compare that to the anus, which only serves solely as waste elimination. Basically, a cloaca is a butthole, and then some! Just a little bit of anatomical distinction for context. <\/p>\n

Researchers made this discovery by studying the embryos of mice and zebrafish, using fluorescent markers to light up which region of each species contained Hox <\/em><\/em>genes, which are responsible for creating extremities. For mouse embryos, it was the digits, whereas for the zebrafish, it was the cloaca. <\/p>\n

Below is an image the Hox gene in zebrafish<\/em><\/em> of one of the zebrafish embryos from the study. <\/p>\n

\n

\"fish
A zebrafish embryo with the cloacal region lit with Hox activity. Brent Hawkins\/UNIGE<\/a><\/figcaption><\/figure>\n

<\/p>\n

While this is just a fun bit of (very weird) trivia to throw out at parties, and perhaps gross out some fellow partygoers, it also provides a rather profound example of just how efficient nature truly is. <\/p>\n

\u201cThe fact that these genes are involved is a striking example of how evolution innovates, recycling the old to make the new,\u201d said Denis Duboule, honorary professor at UNIGE and the Coll\u00e8ge de France and initiator of the study. <\/p>\n

\u201cRather than building a new regulatory system for the digits, nature has repurposed an existing mechanism, initially active in the cloaca.\u201d<\/p>\n

It\u2019s also an interesting depiction of how nature, as cosmic and chaotic as it appears, also tends to repeat itself in patterns. <\/p>\n

“The common feature between the cloaca and the digits is that they represent terminal parts,” wrote geneticist Aur\u00e9lie Hintermann<\/u><\/a>, another researcher in the study.<\/p>\n

“Sometimes they are the end of tubes in the digestive system, sometimes the end of feet and hands, i.e., digits. Therefore, both mark the end of something.”<\/p>\n

Guess it really is true: every new beginning comes from some other beginning\u2019s end.<\/p>\n","protected":false},"excerpt":{"rendered":"

It\u2019s science! <\/p>\n","protected":false},"author":9,"featured_media":187570,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"alternative_headline":"","alternative_description":"","alternative_featured_image":0,"rkv_announcement":{"visible":true},"apple_news_api_created_at":"","apple_news_api_id":"","apple_news_api_modified_at":"","apple_news_api_revision":"","apple_news_api_share_url":"","apple_news_cover_media_provider":"image","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_cover_video_id":0,"apple_news_cover_video_url":"","apple_news_cover_embedwebvideo_url":"","apple_news_is_hidden":"","apple_news_is_paid":"","apple_news_is_preview":"","apple_news_is_sponsored":"","apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":[],"apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"partner_boost":false,"hide_partner_badge":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[280,145],"tags":[2660,2661,2662,2663,2664,2665,589,2666,2667],"sponsor":[],"rkv-people-shadow":[134],"class_list":["post-88","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-internet","category-pop-culture","tag-aquatic-science","tag-biology","tag-evolution","tag-fish","tag-interesting-science","tag-nature","tag-science","tag-scientific-studies","tag-weird-science"],"edit_link":null,"apple_news_notices":[],"rkv_author":{"id":134,"name":"Gemma Davison","display_name":"Gemma Davison","first_name":"","last_name":"","nickname":"","url":"https:\/\/goodinc.com\/qa-upworthy\/author\/gemma-davison\/","link":"https:\/\/goodinc.com\/qa-upworthy\/author\/gemma-davison\/","description":"Gemma Davidson is a former Research Scientist with a degree in Applied Biology. 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