Humans and Acorn Worms Share Common Ancestry, Study Reveals

In a fairly startling disclosure of non-resemblance and perhaps nobody we'd want to invite to Thanksgiving dinner, acorn worms may be a cousin of ours, a recent study revealed. First, what is an acorn worm? It's a small worm-like creature that lives on the ocean floor and feeds through slits in its mouth and esophagus. After sequencing the genomes of two of them, researchers from the Okinawa Institute of Science and Technology (OIST) Graduate University discovered we share more genes with these creatures that we do with many other animals.

About 550 million years ago, an event known as the Cambrian explosion introduced a variety of animals into the world, commonly referred to as deuterostomes. Thanks to modern genome sequencing techniques, scientists are now able to trace the evolutionary radiation of contemporary animals and identify the diverse groups' long-lost ancestor, according to a news release.

In the recent study, researchers sequenced the genomes of two distantly related acorn worm species, Ptychodera flava, collected in Hawaii, and Saccoglossus kowalevskii, from the Atlantic Ocean.

"Their genomes are necessary to fill the gap in our understanding of the genes shared by the common ancestor of all deuterostomes," Dr. Oleg Simakov, lead author of the study, explained.

Researchers then compared the genomes of acorn worms with those of 32 diverse animals and found 8,600 families of genes are shared across deuterostomes, which suggests 70 percent of our genes can be traced back to a common ancestor. This simply means that the human arms, birds' wings, cats' paws and the whales' flippers are all evolutionarily-related, or homologous.

Their study also revealed similar gene clusters found in both the genomes of acorn worms and humans, indicating that the clusters work as a unit to preform common development functions. For example, researchers believe one gene cluster is related to the development of the pharynx, which would mean there is a connection between the function of the modern human thyroid and the filter feeding mechanism 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 life style that ultimately contributed to our evolution," Dr. Simakov added in the release.

Their study was recently published in the journal Nature. 

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