Why Evolution Is True

As most of us know (and all of us who have read WEIT), all vertebrate embryos develop “branchial clefts” (also called “pharyngeal arches” or “branchial arches”) at an early stage, and these are almost certainly the vestigial remnants of the clefts of our fishy ancestors, which develop into gills. Those branchial clefts are sometimes called “gill arches,” even in species, like reptiles, bird, and mammals, that never have gills.  In humans, for example, the clefts disappear and transform into other parts of the body, including the jaw, the middle ear, and the larynx.  Here’s a photo from Wikipedia showing them in humans:

And here they are in a cartilaginous “fish,” a skate (yes, some will take issue with that name, but it’s irrelevant for our purposes):

The second photo is taken from a wonderful new post on the weirdly-named website Playing Chess with Pigeons, written by Troy Britain…

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