Artistic reconstruction of a myllokunmingiid
The myllokunmingiid, the oldest known vertebrate, had two pairs of eyes that helped it navigate and avoid predators.
The earliest ancestors of all animals with backbones, including humans, may have viewed the world with four eyes, not just two.
As a study concluded in January in Naturetraces of these extra eyes persist to this day in the brain, like the pineal organ, which regulates our sleep cycle but no longer forms images.
The first vertebrates “had eyes like we have, but not just eyes like we have. They had four eyes,” said the study’s co-author, Jakob Wintherfrom the University of Bristol, for .
“It’s amazing to think that our ancestors were swimming in the ocean about half a billion years ago and used four eyes to see the world. They probably had a much larger field of vision”, he imagined.
The new study analyzed specimens of two species of myllokunmingids (the oldest known vertebrate), dating back to around 518 million years.
As New Atlas details, the beings had exceptionally preserved four previously located black spots: two larger spots on the sides of the head (interpreted as eyes) and the second pair at the top, between them.
Scientists had previously believed that the second median pair were nasal capsules. However, this was a frustrating inconsistency, as the earliest vertebrates at that time are known to have only had a single nostril.
Using an electron microscope, the team found the presence of melanossomassmall packets that contain melanin. Melanin determines eye color and also absorbs light to create an image.
Researchers also found an impression of a lens inside these organs, “which looked like eyes”said Vinther. This means that the animal had two large eyes on the side and two small eyes on top, and both functioned as chambers”, he added.
The new study proposes that our ancestors were at the base of the food chain, and the four eyes will have evolved amidst environmental pressures of the Cambrian.
Having the ability to detect more of your surroundings and a wider viewing angle is advantageous for avoiding predators.
Over time, the ecological niche changed from filter feeders to carnivores and the second pair of eyes may have then evolved into a non-sensory neuroendocrine organ called pineal glandresponsible for producing melatonin and regulating the sleep cycle.
