Scientists believe they have found the missing peace of the puzzle. Newly discovered deep-sea microbes could explain our evolution from single-cell organisms into complex organisms.
The study, published earlier this week (on Wednesday), does not only explain human evolution, but the evolution of all complex life forms, including animals, plants and even fungi. Collectively they are called eukaryotes.
A team of researchers from Sweden (Uppsala University), Norway (universities in Bergen) and Austria (universities in Vienna) discovered an old species of microbes in the Arctic Ocean, somewhere between Norway and Greenland.
The researchers dubbed the newly found microorganism Loki (short for Lokiarchaeota), an homage to the hydrothermal vent called Loki’s Castle, the exact place underneath the sea where the microorganism was discovered.
It appears to be a transitional life form, sharing trades from both complex and simple life forms, making it the missing link between the two.
Among the most important are lysosomes, compartments that allow eukaryote to destroy defective proteins, but also a malleable cellular skeleton that allows them to change their shape. One theory is that the skeleton enables eukaryotes to crawl over surfaces as protozoans do. Another similarity to eukaryote is Loki’s ability to swallow up molecules or microbes.
Thijs Ettema, lead author of the study, was amazed by the discovery. He gave a statement saying that the evolution of eukaryotes is hard to understand as many evolutionary pieces are still missing, but that the data from Loki “simply looked spectacular”.
When scientists placed Loki in the Tree of Life, it formed a well-supported group with the eukaryotes in scientists’ analyses, according to Lionel Guy, one of the senior scientists working on the study.
Anja Spang, researcher at Uppsala University’s Department of Cell and Molecular Biology and co-lead author of the study, also noted the importance of the study saying that Loki’s genetic structure suggests that cellular complexity emerged in an early stage in the evolution of eukaryotes. Possibly two billion years ago.
The place of discovery should come as no surprise however. Steffen Jorgensen a microbiologist at the University of Bergen informs that “hydrothermal vents are volcanic systems located at the ocean floor. The site where Loki is heavily influenced by volcanic activity, but actually quite low in temperature”, and Jimmy Saw, a co-lead author of the study explains that many unknown organisms can typically be found in extreme environments. Scientists refer to them as “microbial dark matter”, and many even believe that hydrothermal vents might be the location where life on Earth began.
Steffen Jorgensen is also the researcher who first brought sediment from the Arctic Ocean to Ettema’s attention. He noticed archaea, the branch that eukaryotes evolved from, were living in some of the sediment’s layers and contacted Ettema to extract and analyze DNA from the sediment.
The researchers concluded that their work strongly supports the hypotheses that eukaryotes evolved from archaeon and “demonstrate that many components that underpin eukaryote-specific features were already present in that ancestor”.
Dr Ettema added that there is still a lot of research to be done, but suggested that we might have to revise our biology textbooks in the near future.
Image Source: zmescience.com