Scientists Trace Human Eyes to 600-Million-Year-Old One-Eyed Ancestor
Updated
Updated · ScienceDaily · Jul 26
Scientists Trace Human Eyes to 600-Million-Year-Old One-Eyed Ancestor
2 articles · Updated · ScienceDaily · Jul 26
Summary
A 600-million-year-old worm-like marine ancestor with a single median eye may have given rise to vertebrate eyes, including human eyes, according to researchers from Lund University and the University of Sussex.
The team argues that an early ancestor lost its original paired eyes after adopting a mostly stationary, filter-feeding lifestyle, then later repurposed the remaining central light-sensing organ when descendants became active swimmers again.
That route could explain why vertebrate eyes differ sharply from those of insects and squid: the vertebrate retina developed from brain tissue rather than skin on the sides of the head.
Researchers also say the ancient median eye survives in modern vertebrates as the pineal gland, which still links light and darkness to melatonin production and the roughly 24-hour sleep-wake cycle.