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Ancient rock deposits, laid down between two massive ice ages, reveal the oldest known fossils for two types of single-celled creatures: Tube-shelled foraminifera and hairy, vase-shape ciliates.
Both closely resemble microbes living today. But the climate they lived in may have been quite different. The fossils appear in limestone deposited on the ocean floor between 635 million and 715 million years ago. This period was marked by two "Snowball Earth" events, when ice may have covered the entire planet.

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Acidic waste water from a modern mining site supports the same oxygen using bacterial life that appeared on Earth 2.48 billion years ago.

New University of Alberta research shows the first evidence that the first oxygen-breathing bacteria occupied and thrived on land 100 million years earlier than previously thought. The researchers show that the most primitive form of aerobic-respiring life on land came into existence 2.48 billion years ago.
The research team, led by U of A geomicrobiologist Kurt Konhauser, made their find by investigating a link between atmospheric oxygen levels and rising concentrations of chromium in the rock of ancient seabeds.
Pyrite oxidation is a simple chemical process driven by two things: bacteria and oxygen. The researchers say this proves that oxygen levels in Earth's atmosphere increased dramatically during that time.

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Earliest forms of life began in Australia

The findings of a team of Australian and British scientists have broken the current record as the Earth's oldest known forms of microbial life.
They have discovered microscopic fossils, about 3.43 billion years old, in the remote Pilbara region of Western Australia, the Age reported
Until the new discovery, the oldest uncontroversial microbial fossils were 3.2 billion years old, as reported last year from South Africa by Emmanuelle Javaux of Belgiums Liege University.

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Fossil microbes give sulphur insight on ancient Earth

Tiny structures found within 3.4bn-year-old sandstones in Western Australia may represent the oldest direct evidence of life on Earth.
Scientists say their analysis of the microfossils clearly shows the organisms were processing sulphur for energy and growth - not oxygen.
They report their discovery in the journal Nature Geoscience.
The team says the microbe remains offer a fascinating insight into conditions on the ancient Earth.

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Title: The human genome retains relics of its prokaryotic ancestry: human genes of archaebacterial and eubacterial origin exhibit remarkable differences
Authors: David Alvarez-Ponce and James O. McInerney

Eukaryotes are generally thought to stem from a fusion event involving an archaebacterium and a eubacterium. As a result of this event, contemporaneous eukaryotic genomes are chimaeras of genes inherited from both endosymbiotic partners. These two coexisting gene repertoires have been shown to differ in a number of ways in yeast. Here we combine genomic and functional data in order to determine if and how human genes that have been inherited from both prokaryotic ancestors remain distinguishable. We show that, despite being fewer in number, human genes of archaebacterial origin are more highly and broadly expressed across tissues, are more likely to have lethal mouse orthologs, tend to be involved in informational processes, are more selectively constrained, and encode shorter and more central proteins in the protein-protein interaction network than eubacterium-like genes. Furthermore, consistent with Endosymbiotic Theory, we show that proteins tend to interact with those encoded by genes of the same ancestry. Most interestingly from a human health perspective, archaebacterial genes are less likely to be involved in heritable human disease. Taken together, these results illustrate that after more than two billion years of evolution the human genome maintains at least two somewhat distinct communities of genes.

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MSU-led team makes discoveries about major event in history of complex life

A team of scientists led by Montana State University has discovered the "when" of a major event that led to the evolution of complex life on Earth.
Eric Boyd and five other scientists from Montana and Arizona have hypothesized that between 1.5 billion and 2.2 billion years ago, bacteria and single-celled organisms called archaea started producing nitrogen in a useable form. It was the first time that biological processes were involved, and it allowed higher forms of life to flourish.
Microbes started producing fixed nitrogen in a relatively oxygen-free environment, probably in layers of the ocean where fixed nitrogen was limited, Boyd said. The scientists believe that methanogenic archaea were the first to convert nitrogen in the atmosphere into a useable form.
Then, maybe because of genetic transfer, bacteria developed the ability.

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Ancient armour
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Fossils from the Yukon reveal protective plates for microscopic organisms.

In summer 2007, two geologists armed with rock hammers and a shotgun hiked through the Yukon, looking for fossils. For two weeks, Phoebe Cohen, a postdoc in MIT's Department of Earth, Atmospheric and Planetary Sciences, and Francis Macdonald, an assistant professor of geology at Harvard University, set up camp along the Alaska-Canada border in a remote mountain range accessible only via helicopter.
The shotgun came in handy: Macdonald fired it once to scare off a grizzly bear. And the rock hammers proved invaluable - the team worked them against mountainsides, chiselling out rock samples. They hauled the rocks back to Cambridge and made a surprising discovery: The ancient carbonate contained hundreds of incredibly well-preserved fossils resembling tiny, shield-like plates.
Cohen, who was a Harvard PhD student at the time, says single-celled organisms may have produced the plates as armour, in a process called biomineralisation. Today, many organisms have evolved the ability to produce mineral structures: Molluscs generate shells, and mammals and birds form bone. The 700-million-year-old fossils Cohen found may be the oldest evidence of biomineralisation; Cohen, Macdonald and co-authors reported the finding this week in the journal Geology.

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Young Graphite in Old Rocks Challenges Earliest Signs of Life, BC Research Team Shows

Carbon found within ancient rocks has played a crucial role developing a time line for the emergence of biological life on the planet billions of years ago. But applying cutting-edge technology to samples of ancient rocks from northern Canada has revealed the carbon-based minerals may be much younger than the rock they inhabit, Boston College Assistant Professor of Earth and Environmental Sciences Dominic Papineau and a team of researchers report in the latest edition of the journal Nature Geoscience.
The team - which includes researchers from Boston College, the Carnegie Institution of Washington, NASA's Johnson Space Centre and the Naval Research Laboratory - says new evidence from Canada's Hudson Bay region shows carbonaceous particles are millions of years younger than the rock in which they're found, pointing to the likelihood that the carbon was mixed in with the metamorphic rock later than the rock's earliest formation - estimated to be 3.8 to 4.2 billion years ago.

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Protein flaws responsible for complex life

Tiny structural errors in proteins may have been responsible for changes that sparked complex life, researchers say.
A comparison of proteins across 36 modern species suggests that protein flaws called "dehydrons" may have made proteins less stable in water.
This would have made them more adhesive and more likely to end up working together, building up complex function.

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Microbial mats might have functioned as oxygen oases for primitive multicellular life.

Mats of plant-like bacteria dramatically increase local oxygen levels in the lakes where they are found, as a result of photosynthesis. That might have given early multicellular animals the boost they needed to evolve in an ancient world where oxygen was scarce.
A study exploring this idea, published today in Nature Geoscience1, analyses bacterial colonies called microbial mats in the Los Roques lagoons of Venezuela.

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