A study by MBARI and collaborators, published in Nature, has established that comb jellies (ctenophores), rather than sponges, are the most distantly related animals to all others, shedding light on a long-standing question about animal evolution that dates back over 700 million years. By mapping gene linkages—sets of genes found together on chromosomes—the researchers provided compelling evidence that comb jellies form a sibling group to all other animals, differentiating them from sponges. The study utilized advanced genetic sequencing techniques to analyze the complete chromosome lengths of comb jellies and sponges, revealing distinct patterns of gene linkages that have remained largely unchanged throughout evolution. This genetic framework allows scientists to trace back to an ancient evolutionary divergence, where one lineage led to comb jellies while the other evolved into sponges and subsequent animal varieties. Understanding these relationships enhances insights into the evolution of key anatomical features in animals, including the nervous and digestive systems. This groundbreaking research not only clarifies the early branches of the animal family tree but also establishes a foundation for further evolutionary studies. The work was supported by multiple institutions and highlights the significance of genetic organization in comprehending animal biology.
