̽��ֱ�� of Cambridge - Nicholas Tosca

Ancient seafloor vents spewed tiny, life-giving minerals into Earth’s early oceans

cmm201 — Fri, 02 Feb 2024 16:38:44 +0000

Their study, published in Science Advances, examined 3.5-billion-year-old rocks from western Australia in previously unseen detail and identified large quantities of a mineral called greenalite, which is thought to have played a role in early biological processes. ̽��ֱ��researchers also found that the seafloor vents would have seeded the oceans with apatite, a mineral rich in the life-essential element phosphorus.

̽��ֱ��earliest lifeforms we know of—single-celled microorganisms, or microbes—emerged around 3.7 billion years ago. Most of the rocks that contain traces of them and the environment they lived in have, however, been destroyed. Some of the only evidence we have of this pivotal time comes from an outcrop of sediments in the remote Australian outback.

̽��ֱ��so-called Dresser Formation has been studied for years but, in the new study, researchers re-examined the rocks in closer detail, using high magnification electron microscopes to reveal tiny minerals that were essentially hidden in plain sight.

̽��ֱ��greenalite particles they observed measured just a few hundred nanometres in size—so small that they would have been washed over thousands of kilometres, potentially finding their way into a range of environments where they may have kick-started otherwise unfavourable chemical reactions, such as those involved in building the first DNA and RNA molecules.

“We’ve found that hydrothermal vents supplied trillions upon trillions of tiny, highly-reactive greenalite particles, as well as large quantities of phosphorus,” said Professor Birger Rasmussen, lead author of the study from the ̽��ֱ�� of Western Australia.

Rasmussen said scientists are still unsure as to the exact role of greenalite in building primitive cells, “but this mineral was in the right place at the right time, and also had the right size and crystal structure to promote the assembly of early cells.”

̽��ֱ��rocks the researchers studied contain characteristic layers of rusty-red, iron-rich jasper which formed as mineral-laden seawater spewed from hydrothermal vents. Scientists had thought the jaspers got their distinctive red colour from particles of iron oxide which, just like rust, form when iron is exposed to oxygen.

But how did this iron oxide form when Earth’s early oceans lacked oxygen? One theory is that photosynthesising cyanobacteria in the oceans produced the oxygen, and that it wasn’t until later, around 2.4 billion years ago, that this oxygen started to skyrocket in the atmosphere.

̽��ֱ��new results change that assumption, however, “the story is completely different once you look closely enough,” said study co-author Professor Nick Tosca from Cambridge’s Department of Earth Sciences.

̽��ֱ��researchers found that tiny, drab, particles of greenalite far outnumbered the iron oxide particles which give the jaspers their colour. ̽��ֱ��iron oxide was not an original feature, discounting the theory that they were formed by the activity of cyanobacteria.

“Our findings show that iron wasn’t oxidised in the oceans; instead, it combined with silica to form tiny crystals of greenalite,” said Tosca. “That means major oxygen producers, cyanobacteria, may have evolved later, potentially coinciding with the soar in atmospheric oxygen during the Great Oxygenation Event.”

Birger said that more experiments are needed to identify how greenalite might facilitate prebiotic chemistry, “but it was present in such vast quantities that, under the right conditions its surfaces could have synthesized an enormous number of RNA-type sequences, addressing a key question in origin of life research – where did all the RNA come from?”

Reference:
Rasmussen, B, Muhling, J, Tosca, N J. 'Nanoparticulate apatite and greenalite in oldest, well-preserved hydrothermal vent precipitates.' Science Advances (2024). DOI: 10.1126/sciadv.adj4789

Researchers from the universities of Cambridge and Western Australia have uncovered the importance of hydrothermal vents, similar to underwater geysers, in supplying minerals that may have been a key ingredient in the emergence of early life.

MARUM − Zentrum für Marine Umweltwissenschaften, Universität Bremen

̽��ֱ��hydrothermal vent 'Candelabra' in the Logatchev hydrothermal field on the Mid-Atlantic Ridge at a water depth of 3300 metres.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

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Explore life in the Universe with new postgraduate programme

lw355 — Mon, 18 Sep 2023 10:00:19 +0000

A new postgraduate programme will train researchers to understand life's origins, search for habitable planets and consider the most profound question of all: are we alone?

Seawater could have provided phosphorous required for emerging life

cmm201 — Tue, 27 Sep 2022 13:40:56 +0000

Their results, published in the journal Nature Communications, show that seawater might be the missing source of phosphate, meaning that it could have been available on a large enough scale for life without requiring special environmental conditions.

“This could really change how we think about the environments in which life first originated,” said co-author Professor Nick Tosca from Cambridge's Department of Earth Sciences.

̽��ֱ��study, which was led by Matthew Brady, a PhD student from Cambridge's Department of Earth Sciences, shows that early seawater could have held one thousand to ten thousand times more phosphate than previously estimated — as long as the water contained a lot of iron.

Phosphate is an essential ingredient in creating life’s building blocks — forming a key component of DNA and RNA — but it is one of the least abundant elements in the cosmos in relation to its biological importance. When in its mineral form, phosphate is also relatively inaccessible — it can be hard to dissolve in water so that life can use it.

Scientists have long suspected that phosphorus became part of biology early on, but they have only recently begun to recognize the role of phosphate in directing the synthesis of molecules required by life on Earth. “Experiments show it makes amazing things happen – chemists can synthesize crucial biomolecules if there is a lot of phosphate in solution,” said Tosca.

But the exact environment needed to produce phosphate has been a topic of discussion. Some studies have suggested that when iron is abundant then phosphate should actually be even less accessible to life. This is, however, controversial because early Earth would have had an oxygen-poor atmosphere where iron would have been widespread.

To understand how life came to depend on phosphate, and the sort of environment that this element would have formed in, they carried out geochemical modelling to recreate early conditions on Earth.

“It’s exciting to see how simple experiments in a bottle can overturn our thinking about the conditions that were present on the early Earth,” said Brady.

In the lab, they made up seawater with the same chemistry thought to have existed in Earth’s early history. They also ran their experiments in an atmosphere starved of oxygen, just like on ancient Earth.

̽��ֱ��team’s results suggest that seawater itself could have been a major source of this essential element.

“This doesn’t necessarily mean that life on Earth started in seawater,” said Tosca, “It opens up a lot of possibilities for how seawater could have supplied phosphate to different environments— for instance, lakes, lagoons, or shorelines where sea spray could have carried the phosphate onto land.”

Previously scientists had come up with a range of ways of generating phosphate, some theories involving special environments such as acidic volcanic springs or alkaline lakes, and rare minerals found only in meteorites.

“We had a hunch that iron was key to phosphate solubility, but there just wasn’t enough data,” said Tosca. ̽��ֱ��idea for the team’s experiments came when they looked at waters that bathe sediments deposited in the modern Baltic Sea. “It is unusual because it's high in both phosphate and iron — we started to wonder what was so different about those particular waters.”

In their experiments, the researchers added different amounts of iron to a range of synthetic seawater samples and tested how much phosphorous it could hold before crystals formed and minerals separated from the liquid. They then built these data points into a model that could predict how much phosphate ancient seawater could hold.

̽��ֱ��Baltic Sea pore waters provided one set of modern samples they used to test their model. “We could reproduce that unusual water chemistry perfectly,” said Tosca. From there they went on to explore the chemistry of seawater before any biology was around.

̽��ֱ��results also have implications for scientists trying to understand the possibilities for life beyond Earth. “If iron helps put more phosphate in solution, then this could have relevance to early Mars,” said Tosca.

Evidence for water on ancient Mars is abundant, including old river beds and flood deposits, and we also know that there was a lot of iron at the surface and the atmosphere was at times oxygen-poor, said Tosca.

Their simulations of surface waters filtering through rocks on the Martian surface suggest that iron-rich water might have supplied phosphates in this environment too.

“It’s going to be fascinating to see how the community uses our results to explore new, alternative pathways for the evolution of life on our planet and beyond,” said Brady.

Reference:
Matthew P Brady et al. 'Marine phosphate availability and the chemical origins of life on Earth.' Nature Communications (2022). DOI: 10.1038/s41467-022-32815-x

̽��ֱ��problem of how phosphorus became a universal ingredient for life on Earth may have been solved by researchers from the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Cape Town, who have recreated primordial seawater containing the element in the lab.

This could really change how we think about the environments in which life first originated

Nick Tosca

NASA

Artist Concept of an Early Earth

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Cambridge researcher joins NASA science mission searching for signs of past life on Mars

sc604 — Thu, 18 Feb 2021 11:57:31 +0000

Professor Nicholas Tosca from the ̽��ֱ�� of Cambridge is the only UK scientist selected by NASA to be part of the core science team for the Mars Perseverance 2020 mission, which is searching for signs of past life on the red planet.