All animals evolved from a single ancestor and scientists want to know more about how that happened. More than half a billion years ago, long before humans appeared, the first split in the tree separated one lineage from all other animals. Traditionally, scientists have thought it was sponges.
The evidence in favor of comb jellies comes from deciphering the first complete genetic code from a member of this group. Scientists were finally able to compare the full DNA codes from all the earliest branches.