Dr Simon Poulton, Civil Engineering and Geosciences, Newcastle University, was part of an international team of biogeochemists who took part in the University of California-led study.
The study’s results are published in today’s edition of Nature (27th March).
‘For decades it was assumed that the ocean became oxygenated shortly after an initial rise in atmospheric oxygen about 2.4 billion years ago,’ said Dr Poulton. ‘This study provides independent confirmation that there was a major delay in the oxygenation of the ocean, and furthermore, it now appears that the availability of molybdenum may have played a crucial role in animal evolution.
‘At last, a coherent picture of the environmental conditions that led to the evolution of animal life is emerging.’
The researchers arrived at their conclusion after tracking molybdenum in black shales, a kind of sedimentary rock rich in organic matter found in the ocean. Molybdenum is a key micronutrient for the life-forms that control the production of oceanic and atmospheric oxygen.
Following the initial rise of oxygen in the Earth’s atmosphere 2.4 billion years ago, oxygen was transferred to the surface ocean to support oxygen-demanding micro-organisms. However, the diversity of these single-celled life forms remained low, and their multi-cellular descendents (animals) did not appear until about 600 million years ago.
Suspecting that deficiencies in oxygen and molybdenum might explain this evolutionary lag, the team measured the abundance of molybdenum in ancient marine sediments over time to estimate how much of the metal had been dissolved in the seawater in which the sediments formed.
The researchers found significant, firsthand evidence for a molybdenum-depleted ocean compared to the high levels measured in today’s oxygen-rich seawater.
‘These molybdenum depletions may have retarded the development of complex life such as animals for almost two billion years of Earth’s history,’ said project leader Professor Timothy Lyons, at the University of California’s Department of Earth Sciences. ‘The amount of molybdenum in the ocean probably played a major role in the development of early life.
‘As in the case of iron today, molybdenum can be thought of as a life-affirming micro-nutrient that regulates the biological cycling of nitrogen in the ocean.
‘At the same time, molybdenum’s low abundance in the early ocean highlights the global extent of oxygen-poor seawater and implies that the amount of oxygen in the atmosphere was still low.
‘Knowing the amount of oxygen in the early ocean is important for many reasons, including a refined understanding of how and when appreciable oxygen first began to accumulate in the atmosphere.
‘These steps in oxygenation are what ultimately gave rise to the first animals almost 600 million years ago – just the last tenth or so of Earth’s history.’
For animal life to commence, survive and eventually expand on Earth, a threshold amount of oxygen – estimated to be on the order of 1 to 10 percent of present atmospheric levels of oxygen – was needed.
Past research has shown that Earth’s oxygenation occurred in two major steps: The first step, around 2.4 billion years ago, took place as the ocean transformed to a state where only the surface ocean was oxygenated by photosynthesizing bacteria, while the deep ocean was relatively oxygen-free.
The second step, around 600 million years ago, marked the point when the entire ocean became fully oxygenated through a process not yet fully understood. The purpose of this research was to find out the state of the ocean between the two steps.
By tracking molybdenum in shales rich in organic matter, researchers found the deep ocean remained oxygen and molybdenum-deficient after the first step. This condition may have had a negative impact on the evolution of early eukaryotes, our single-celled ancestors. The molybdenum record also shows that the deep ocean only became fully oxygenated by around 550 million years ago.
According to this research, the timing of the oxygenation steps suggests that significant events in Earth’s history are related. Scientists have long speculated that the evolution of the first animals was somehow linked to the so-called Snowball Earth hypothesis, where the Earth was covered from pole to pole in a thick sheet of ice for millions of years. Oxygenation of the oceans and the evolution of animal life occurred shortly after the last of Earth’s global glaciations.
New technologies and computing power to help strengthen population data
22.03.2018 | University of Southampton
New interactive map shows climate change everywhere in world
22.03.2018 | University of Cincinnati
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.
In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...
19.03.2018 | Event News
16.03.2018 | Event News
13.03.2018 | Event News
22.03.2018 | Trade Fair News
22.03.2018 | Earth Sciences
22.03.2018 | Earth Sciences