MAY 21, 2021 3:38 PM PDT

Oxygen Conditions Needed for Emergence of Complex Life Discovered

WRITTEN BY: Annie Lennon

For some time, scientists have supported the ‘Oxygen Control Hypothesis’. The theory states that higher levels of atmospheric oxygen increase the size to which multicellular organisms can grow. Now though, researchers at the Georgia Institute of Technology have finally been able to test the theory, and have found that it may all be more complex. 

People have long believed that oxygen levels on the Earth’s surface are helpful and in some cases even a precondition for the growth of large, complex, multicellular organisms. As scientists did not have a model system capable of undergoing lots of evolutionary generations quickly over a full range of oxygen conditions in the past, however, researchers have not been able to test the theory. But this is now no longer the case. 

For the study, the researchers evolved snowflake yeast, simple multicellular organisms capable of rapid evolutionary change. Using techniques from directed evolution, synthetic biology and mathematical modelling, the researchers varied their growth environment and observed how they evolved over 800 generations in the lab, with a selection for a larger size. 

The results ended up surprising the researchers. They found that large size was easily achieved either when yeast had no oxygen or plenty of it, but not when oxygen was present at low levels. 

"We did a lot more work to show that this is actually a totally predictable and understandable outcome of the fact that oxygen, when limiting, acts as a resource -- if cells can access it, they get a big metabolic benefit.” says Ratcliff. 

“When oxygen is scarce, it can't diffuse very far into organisms, so there is an evolutionary incentive for multicellular organisms to be small -- allowing most of their cells access to oxygen -- a constraint that is not there when oxygen simply isn't present, or when there's enough of it around to diffuse more deeply into tissues."

Ratcliff continued to say that his group’s research helps explain why so little evolutionary progress occurred among multicellular organisms in the billion years after the Great Oxygenation Event 2.5 billion years ago. Known as the ‘Dullest Time in Earth’s History’, it was a period when oxygen was only present at low levels in the atmosphere, and when multicellular organisms remained small and simple. 

 

Sources: EurekAlertNature Communications

About the Author
University College London
Annie Lennon is a writer whose work also appears in Medical News Today, Psych Central, Psychology Today, and other outlets. When she's not writing, she is COO of Xeurix, an HR startup that assesses jobfit from gamified workplace simulations.
You May Also Like
AUG 03, 2022
Space & Astronomy
Moon lava pits might be toasty environments for future astronauts
AUG 03, 2022
Moon lava pits might be toasty environments for future astronauts
In a recent study published in Geophysical Research Letters, a collaborative research team from the University of Califo ...
SEP 19, 2022
Space & Astronomy
Life on Earth: Could More of the Surface Be Habitable?
SEP 19, 2022
Life on Earth: Could More of the Surface Be Habitable?
In a paper recently published in The Astronomical Journal, a group of researchers upended two long-held scientific assum ...
SEP 24, 2022
Space & Astronomy
The James Webb Space Telescope Observes Neptune and its Rings
SEP 24, 2022
The James Webb Space Telescope Observes Neptune and its Rings
The James Webb Space Telescope (JWST) has captured its first image of Neptune, and it is the clearest view of the planet ...
OCT 10, 2022
Space & Astronomy
Using Silicon-Germanium Transistor Technology to Explore Europa
OCT 10, 2022
Using Silicon-Germanium Transistor Technology to Explore Europa
In a recent study presented at the IEEE Nuclear and Space Radiation Effects Conference in July 2022, a research team led ...
OCT 27, 2022
Space & Astronomy
Star Remains Coughed Up by Black Hole
OCT 27, 2022
Star Remains Coughed Up by Black Hole
In a recent study published in The Astrophysical Journal, an international team of researchers led by the Center for Ast ...
NOV 11, 2022
Chemistry & Physics
Grad Student Highlights: Andrew Saydjari (Harvard University)
NOV 11, 2022
Grad Student Highlights: Andrew Saydjari (Harvard University)
This interview series is focused on the graduate student experience across all STEM fields that allows them to get their ...
Loading Comments...