The Closest Living Relative of the First Animal Has Finally Been Found

Ctenophores, also called comb jellies, are the sister group of all living animals, scientists have discovered. The team compared the comb jelly Bolinopsis microptera to sponges — another contender for the most ancient creature on Earth — along with three unicellular relatives of animals. The pattern of genes on the jellies’ chromosomes revealed that they evolved first. That means that early animals were surprisingly complex: they had a well-developed nervous system, and could probably swim around freely.