Pineal gland as ancient eye remnant

New phylogenetic mapping suggests vertebrate eyes descend from a 600‑million‑year‑old worm‑like ancestor with a single median eye; when that lineage later reacquired paired eyes the original central light‑sensor persisted and evolved into the pineal gland, which still mediates light‑linked circadian signals in vertebrate brains. The paper ties changes in eye anatomy to lifestyle shifts (sedentary filter‑feeding vs free‑swimming) and to the later evolution of faster phototransduction proteins that underpin keen vertebrate vision. — This reframes a common cultural idea — that our eyes are a simple forward line of improvement — into a more complex story of loss, reuse, and brain‑based light‑sensing, with implications for neuroscience, chronobiology, and public narratives about human uniqueness.