The ctenophore’s brain suggests that, if evolution began again, intelligence would re-emerge because nature repeats itself

Douglas Fox in Aeon:

Leonid Moroz has spent two decades trying to wrap his head around a mind-boggling idea: even as scientists start to look for alien life in other planets, there might already be aliens, with surprisingly different biology and brains, right here on Earth. Those aliens have hidden in plain sight for millennia. They have plenty to teach us about the nature of evolution, and what to expect when we finally discover life on other worlds.

Moroz, a neuroscientist, saw the first hint of his discovery back in the summer of 1995, not long after arriving in the United States from his native Russia. He spent that summer at the Friday Harbor marine laboratory in Washington. The lab sat amid an archipelago of forested islands in Puget Sound – a crossroads of opposing tides and currents that carried hundreds of animal species past the rocky shore: swarms of jellyfish, amphipod crustaceans, undulating sea lilies, nudibranch slugs, flatworms, and the larvae of fish, sea stars and countless other animals. These creatures represented not just the far reaches of Puget Sound, but also the farthest branches of the animal tree of life. Moroz spent hours out on the pier behind the lab, collecting animals so he could study their nerves. He had devoted years to studying nervous systems across the animal kingdom, in hopes of understanding the evolutionary origin of brains and intelligence. But he came to Friday Harbor to find one animal in particular.

He trained his eyes to recognise its bulbous, transparent body in the sunlit water: an iridescent glint and fleeting shards of rainbow light, scattered by the rhythmic beating of thousands of hair-like cilia, propelling it through the water. This type of animal, called a ctenophore (pronounced ‘ten-o-for’ or ‘teen-o-for’), was long considered just another kind of jellyfish. But that summer at Friday Harbor, Moroz made a startling discovery: beneath this animal’s humdrum exterior was a monumental case of mistaken identity. From his very first experiments, he could see that these animals were unrelated to jellyfish. In fact, they were profoundly different from any other animal on Earth.

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