Lokiarchaeota are microorganisms recently discovered deep beneath the surface of the Atlantic Ocean, and the newly discovered life form could be a missing link in the formation of mulch-cellular life.
Complex cellular life first evolved on Earth roughly 2 billion years ago. For roughly 1.5 billion years before that time, only simple, single cells populated the planet. The evolution of complex cellular life was essential for the development of advanced life-forms on Earth. However, how and why this came about was a mystery to scientists studying the question.
The life-forms were recovered from 1.5 miles beneath the surface of the ocean, near a hydrothermal vent system known as Loki's Castle. This feature is found in the Mid-Atlantic Ridge, sitting 7,700 feet beneath the waters between Norway and Greenland.
Eukaryotes, complex varieties of cells, were the building blocks of all complex forms of life, including fish, dinosaurs, and humans. These typically have a distinct nucleus within their membranes, in addition to a variety of organelles to carry out biological functions.
The group of prokaryotes known as Archaea, of which Loki are a member, do not possess true nuclei. However, analysis of the cells reveal significant adaptations in their genes similar to those seen in more complex cells. This could have provided the ancient organisms with a "starter kit" as they evolved into more complex forms over the next 2 billion years.
"Humans have always been interested in trying to find an answer to the question, 'Where do we come from?' Well, now we know from what type of microbial ancestor we descend. Essentially, Lokiarchaeota represent a missing piece of the puzzle of the evolution from simple cells - bacteria and archaea, prokaryotes - to complex cells - eukaryotes, which includes us humans," said Thijs Ettema, an evolutionary microbiologist with Uppsala University.
Loki was the Norse god of fire, known for playing pranks and tricks. The geothermal vents named after the deity spout water out at 570 degrees Fahrenheit. However, just nine miles away, under the seabed, where Lokiarchaeota were found, temperatures hover around freezing, and oxygen is in poor supply. Hydrothermal vents are known for being centers of diverse, highly unusual forms of life.
Archaea were first discovered in the 1970s by biologist Carl Woese, and this finding added a new branch to the tree of life. Biologists were astounded how these simple organisms could lead to more complex forms of life.
Discovery of Loki and analysis of how the microorganisms can fit into the family tree of life, including human beings, was detailed in the journal Nature.
Photo: NOAA Photo Library | Flickr
