A genome sequencing study conducted by researchers from the Okinawa Institute of Science and Technology Graduate University (OIST) revealed that two species of slimy seabed worms possess more human-like genes than any other animals. In fact, the species share approximately 70 percent of human genes, making the authors dubbed it as "humans' distant cousins."
Acorn worms or enteropneust hemichordates, together with echinoderms and chordates are the three phyla that compose deuterostomes. These species are marine invertebrates that have the same characteristics. In the study, the researchers investigated two specific species of acorn worms, called Saccoglossus kowalevskii and Ptychodera flava to draft its genomic sequences.
After sequencing and comparing the genomes with that of 32 different animals, the authors discovered a total of 8,716 sets of homologous or evolutionarily-related genes in the acorn worms that are shared among all deuterostomes.
Due to gene duplications and other processes that transpired throughout history, these sets of similar genes conform to at least 14,000 genes (70 percent) of the present human genome.
The researchers were also able to determine groups of genes that are close together in genomes of humans and other vertebrates, as well as in acorn worms. These clusters are active in humans as it form the pharynx and thyroid glands. In acorn worms, these genes play a role in gill development, which may explain the species' food filtering and breathing mechanisms. Such finding led the scientists to suggest that there might be a link between modern thyroid processes and feeding of acorn worms.
"Our analysis of the acorn worm genomes provides a glimpse into our Cambrian ancestors' complexity and supplies support for the ancient link between the pharyngeal development and the filter feeding lifestyle that ultimately contributed to our evolution," said Dr. Oleg Simakov, the study's lead author.
While analysis of acorn worms can help researchers discover many things about present-day species, the authors of the study said there is still so much more to find out. Simakov has expressed his willingness to broaden genomic analysis to entail more under-investigated areas across the ever-extending biological world.
The study was published in the journal Nature on Wednesday, Nov. 18.
