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Acorn worms share many of the genome sequences that humans have.
BEACON TRANSCRIPT – Acorn worms may be man’s weirdest distant relatives as researchers have found that they share almost 70 percent of their genetic ancestry with that of human beings. Two species of worms known as Ptychodera flava and Saccoglossus kowalevskii were analyzed and their genomes were compared to the genome sequences of other animals including humans. The worms were found to have several gene sequences that humans had on the same chromosome.
It seems that the human genome matches with the genomes that these worms have up to as much as 70 percent. The acorn worms and the human beings share a common ancestor of all the deuterostomes, which lived approximately half a billion years ago. Around that time there was a split within the genetic line which caused the formation of the pharynx system that both humans and animals use today. This pharynx system was different from the gill system that the worms use.
Researchers have explained that the genes we share with the acorn worms are very old and have been since lost in many animals as they evolved. However what is baffling is how much has changed in the evolution of the different species while such a large part of the genetic code has remained the same.
Acorn worms are one of the three phyla that compose deuterostomes, alongside echinoderms and chordates. They still maintain many similarities to the animals that first evolved pharyngeal slits on a genetic level. It seems the common ancestry that we share with the worms is what is responsible for the evolution of animals with backbones and hollow nerve cords, which can be found nowadays in vertebrates including humans.
The presence of the pharyngeal slits gave scientists insight into how the latter species evolved: these slits first evolved into gills in order to extract oxygen and later on developed into the pharynx system that human beings and other animals use. The fact that the acorn worms have these slits show us that the last common ancestor that we shared with the worms also had them and was more likely than not a filter feeder just like the acorn worms are now.
The acorn worm might be the most unusual distant relative that the human species has considering how different it is. Acorn worms live in u-shaped burrows carved in the ocean floor and feed on microorganisms found in the sand beneath the murky water.
Image source: https://en.wikipedia.org
