Discovery of the First Branch on the Tree of Life.

Scientists have used chromosomal analysis techniques to determine that the comb jelly was the first animal to branch off from the common ancestor of all animals on Earth, rather than the sea sponge. By comparing the placements of certain groups of genes in sponges and comb jellies to their closest single-cell non-animal relatives, researchers found that the comb jelly had the least reshuffling of genes on chromosomes, indicating that it split off from the original genome first. This discovery sheds light on the history of animal evolution and the mechanisms powering it.