from the meet-your-great-great-great...-great-grandparents dept.
According to a new fossil analysis, previously described Australian fossils do contain evidence of 3.5-billion-year-old microbial life. However, the complexity of the fossilized microbes suggests that life arose much earlier, possibly as far back as 4 billion years ago:
In 1992, researchers discovered evidence of what was then potentially the earliest life on Earth: 3.5-billion-year-old microscopic squiggles encased in Australian rocks. Since then, however, scientists have debated whether these imprints truly represent ancient microorganisms, and even if they do, whether they're really that old. Now, a comprehensive analysis of these microfossils suggests that these formations do indeed represent ancient microbes, ones potentially so complex that life on our planet must have originated some 500 million years earlier.
The new work indicates these early microorganisms were surprisingly sophisticated, capable of photosynthesis and of using other chemical processes to get energy, says Birger Rasmussen, a geobiologist at Curtin University in Perth, Australia, who was not involved with the work. The study "will probably touch off a flurry of new research into these rocks as other researchers look for data that either support or disprove this new assertion," adds Alison Olcott Marshall, a geobiologist at the University of Kansas in Lawrence who was not involved in the effort.
[...] The analysis detected several distinct carbon ratios in the material [DOI: 10.1073/pnas.1718063115] [DX], Schopf, Valley, and colleagues report today in the Proceedings of the National Academy of Sciences. Two types of microfossils had the same carbon ratio as modern bacteria that use light to make carbon compounds that fuel their activities—a primitive photosynthesis that did not involve oxygen. Two other types of microfossils had the same carbon ratios as microbes known as archaea that depend on methane as their energy source—and that played a pivotal role in the development of multicellular life. The ratio of a final type of microfossil indicated that this organism produced methane as part of its metabolism.
That there are so many different carbon ratios strengthens the case that these are real fossils, Schopf says. Any inorganic processes that could have created the squiggles would be expected to leave a uniform carbon ratio signature, he says. The fact that microbes were already so diverse at this point in Earth's history also suggests that life on our planet may date back to 4 billion years ago, he says. Other researchers have found signs of life dating back at least that far, but those findings are even more controversial than Schopf's.
Also at University of Wisconsin-Madison.
Previously: Ancient Rocks Record First Evidence for Photosynthesis That Made Oxygen
3.7 Billion-Year-Old Fossil Found
Oldest Evidence of Life on Earth Found in 3.77-4.28 Billion Year Old Fossils
Earliest Known Evidence for Microbial Life on Land: 3.48 Billion Years Old
Related Stories
A new study shows that iron-bearing rocks that formed at the ocean floor 3.2 billion years ago carry unmistakable evidence of oxygen. The only logical source for that oxygen is the earliest known example of photosynthesis by living organisms, say University of Wisconsin-Madison geoscientists.
"Rock from 3.4 billion years ago showed that the ocean contained basically no free oxygen," says Clark Johnson, professor of geoscience at UW-Madison and a member of the NASA Astrobiology Institute. "Recent work has shown a small rise in oxygen at 3 billion years. The rocks we studied are 3.23 billion years old, and quite well preserved, and we believe they show definite signs for oxygen in the oceans much earlier than previous discoveries."
The most reasonable candidate for liberating the oxygen found in the iron oxide is cyanobacteria, primitive photosynthetic organisms that lived in the ancient ocean. The earliest evidence for life now dates back 3.5 billion years, so oxygenic photosynthesis could have evolved relatively soon after life itself.
Until recently, the conventional wisdom in geology held that oxygen was rare until the "great oxygenation event," 2.4 to 2.2 billion years ago.
Scientists have found evidence of microbial life in a fossil dated to 3.7 billion years ago:
Rapid emergence of life shown by discovery of 3,700-million-year-old microbial structures (DOI: 10.1038/nature19355) (DX)
Biological activity is a major factor in Earth's chemical cycles, including facilitating CO2 sequestration and providing climate feedbacks. Thus a key question in Earth's evolution is when did life arise and impact hydrosphere–atmosphere–lithosphere chemical cycles? Until now, evidence for the oldest life on Earth focused on debated stable isotopic signatures of 3,800–3,700 million year (Myr)-old metamorphosed sedimentary rocks and minerals from the Isua supracrustal belt (ISB), southwest Greenland. Here we report evidence for ancient life from a newly exposed outcrop of 3,700-Myr-old metacarbonate rocks in the ISB that contain 1–4-cm-high stromatolites—macroscopically layered structures produced by microbial communities. [...] The ISB stromatolites predate by 220 Myr the previous most convincing and generally accepted multidisciplinary evidence for oldest life remains in the 3,480-Myr-old Dresser Formation of the Pilbara Craton, Australia.
Reported at BBC, Ars Technica, and Reuters.
Scientists have found fossilized microbes that they have dated to between 3.77 and 4.28 billion years old:
The fossil structures were encased in quartz layers in the so-called Nuvvuagittuq Supracrustal Belt (NSB). The NSB is a chunk of ancient ocean floor. It contains some of the oldest volcanic and sedimentary rocks known to science.
The team looked at sections of rock that were likely laid down in a system of hydrothermal vents - fissures on the seabed from which heated, mineral-rich waters spew up from below. Today, such vents are known to be important habitats for microbes. And Dr Dominic Papineau, also from UCL, who discovered the fossils in Quebec, thinks this kind of setting was very probably also the cradle for lifeforms between 3.77 and 4.28 billion years ago (the upper and lower age estimates for the NSB rocks).
[...] At present, perhaps the oldest acknowledged evidence of life on the planet is found in 3.48-billion-year-old rocks in Western Australia. This material is said to show remnants of stromatolites - mounds of sediment formed of mineral grains glued together by ancient bacteria. An even older claim for stromatolite traces was made in August last year. The team behind that finding said their fossil evidence was 3.70 billion years old. [...] Part of the interest in ancient life is in the implication it has for organisms elsewhere in the Solar System. "These (NTB) organisms come from a time when we believe Mars had liquid water on its surface and a similar atmosphere to Earth at that time," said Mr Dodd. "So, if we have lifeforms originating and evolving on Earth at this time then we may very well have had life beginning on Mars."
Evidence for early life in Earth's oldest hydrothermal vent precipitates (DOI: 10.1038/nature21377) (DX)
Fossils discovered by UNSW scientists in 3.48 billion year old hot spring deposits in the Pilbara region of Western Australia have pushed back by 580 million years the earliest known existence of microbial life on land. Previously, the world's oldest evidence for microbial life on land came from 2.7- 2.9 billion-year-old deposits in South Africa containing organic matter-rich ancient soils.
"Our exciting findings don't just extend back the record of life living in hot springs by 3 billion years, they indicate that life was inhabiting the land much earlier than previously thought, by up to about 580 million years," says study first author, UNSW PhD candidate, Tara Djokic. "This may have implications for an origin of life in freshwater hot springs on land, rather than the more widely discussed idea that life developed in the ocean and adapted to land later."
Scientists are considering two hypotheses regarding the origin of life. Either that it began in deep sea hydrothermal vents, or alternatively that it began on land in a version of Charles Darwin's "warm little pond". "The discovery of potential biological signatures in these ancient hot springs in Western Australia provides a geological perspective that may lend weight to a land-based origin of life," says Ms Djokic.
Earliest signs of life on land preserved in ca. 3.5 Ga hot spring deposits (open, DOI: 10.1038/ncomms15263) (DX)
Previously:
3.7 Billion-Year-Old Fossil Found
Oldest Evidence of Life on Earth Found in 3.77-4.28 Billion Year Old Fossils
Researchers Use Genetic Analysis to Determine That Comb Jellies Were the Earliest Animals
The presence of large quantities of oxygen ions may be able to distinguish habitable exoplanets with life from barren exoplanets in the habitable zone (resembling Venus or Mars):
Like Earth, Venus and Mars are small rocky planets; they have permanent atmospheres like Earth, and their atmospheres are exposed to the same solar radiation as Earth's. Data from the Pioneer Venus Orbiter and the Viking descent probe on Mars show that they have very similar ionospheres to each other—which don't contain a lot of atomic O+ ions. Know what else Venus and Mars are missing? Photosynthesis.
[Astronomy PhD candidate Paul] Dalba's contention is that photosynthesis on a planet's surface, which generates a surfeit of molecular oxygen, is the only thing that can account for these atomic O+ ions in a planet's ionosphere. The mere existence of life throws a planet's atmosphere out of chemical balance. O+ would be a neat biomarker because there isn't a numerical cutoff required—just the dominance of O+ among the ionic species in the upper atmosphere would indicate "thriving global biological activity" on the planet below.
Dalba claims that Venus and Mars act as negative controls, demonstrating that planets like Earth but lacking life don't have this O+ layer. Some may think that continuous volcanic activity on the surface could also generate enough oxygen, but Dalba doesn't. Chemistry involving water and UV light [open, DOI: 10.1038/srep13977] [DX] can also release oxygen. But the amount of water on Earth is insufficient to account for the requisite oxygen content, so he thinks that the presence of water on other planets wouldn't make enough oxygen there either.
Atomic oxygen ions as ionospheric biomarkers on exoplanets (DOI: 10.1038/s41550-017-0375-y) (DX)
Related: Nitrogen in Ancient Rocks a Sign of Early Life
Oxygen Ions From Earth Escape to the Moon
Researchers Suffocate Hopes of Life Support in Red Dwarf "Habitable Zones"
Seven Earth-Sized Exoplanets, Including Three Potentially Habitable, Identified Around TRAPPIST-1
Cosmic Methyl Chloride Detection Complicates the Search for Life on Exoplanets
Mars Colonists Could Produce Oxygen by Making a Plasma Out of Atmospheric Carbon Dioxide
Analysis of Microfossils Finds that Microbial Life Existed at Least 3.5 Billion Years Ago
To Detect Life on Other Planets, Look for Methane, Carbon Dioxide, and an Absence of Carbon Monoxide
Geologists Question 'Evidence Of Ancient Life' In 3.7 Billion-Year-Old Rocks
The oldest evidence of life on Earth probably isn't found in some 3.7 billion-year-old rocks found in Greenland, despite what a group of scientists claimed [DOI: 10.1038/nature19355] [DX] a couple of years ago. That's according to a new analysis [DOI: 10.1038/s41586-018-0610-4] [DX], published Wednesday in the journal Nature by a different team of experts. This second group examined structures within the rock that were thought in 2016 to have been produced by communities of single-celled microbes that grew up from the bottom of a shallow, salty sea. A three-dimensional look at these structures shows that instead of having a telltale upside-down ice-cream cone shape — the kind produced by microorganisms — they are shaped like a Toblerone candy bar.
"They're stretched-out ridges that extend deeply into the rock," said Joel Hurowitz, a geochemist at Stony Brook University in New York and an author of Wednesday's paper. "That shape is hard to explain as a biological structure and much easier to explain as something that resulted from rocks being squeezed and deformed under tectonic pressures." Asked what the chances were that the structures were created by ancient microbes, astrobiologist Abigail Allwood — of NASA's Jet Propulsion Laboratory and lead author of this second analysis — said: "I don't think there's much chance at all."
[...] All of this is vigorously disputed by the researchers who originally claimed that the Greenland rocks contained the world's oldest fossils. They stand by that claim and say that Allwood and her colleagues based their work on just a cursory, one-day visit to the site. [...] Vickie Bennett, of the Australian National University, added that she found the new study "disappointing" and "unfortunate" in that it "only serves to confuse" the earlier research that she and her colleagues did on these ancient rocks. "Basically they did not look at the same rocks — and the details matter," Bennett told NPR in an email. In her view, the rocks in the current study are a "poor-cousin equivalent to the rocks of our original study" and the new analysis "was not conducted with care."
The article does not address evidence found in Quebec in 2017, dated to between 3.77 and 4.28 billion years ago.
Also at USA Today.
Previously: 3.7 Billion-Year-Old Fossil Found
Earliest Known Evidence for Microbial Life on Land: 3.48 Billion Years Old
Analysis of Microfossils Finds that Microbial Life Existed at Least 3.5 Billion Years Ago - "However, the complexity of the fossilized microbes suggests that life arose much earlier, possibly as far back as 4 billion years ago."
Chemists have found a series of chemical reactions that could have led to the first life on Earth:
Chemists at The Scripps Research Institute (TSRI) have developed a fascinating new theory for how life on Earth may have begun. Their experiments, described today in the journal Nature Communications, demonstrate that key chemical reactions that support life today could have been carried out with ingredients likely present on the planet four billion years ago.
[...] For the new study, Krishnamurthy and his coauthors, who are all members of the National Science Foundation/National Aeronautics and Space Administration Center for Chemical Evolution, focused on a series of chemical reactions that make up what researchers refer to as the citric acid cycle.
[...] Leaders of the new study started with the chemical reactions first. They wrote the recipe and then determined which molecules present on early Earth could have worked as ingredients. The new study outlines how two non-biological cycles—called the HKG cycle and the malonate cycle—could have come together to kick-start a crude version of the citric acid cycle. The two cycles use reactions that perform the same fundamental chemistry of a-ketoacids and b-ketoacids as in the citric acid cycle. These shared reactions include aldol additions, which bring new source molecules into the cycles, as well as beta and oxidative decarboxylations, which release the molecules as carbon dioxide (CO2).
As they ran these reactions, the researchers found they could produce amino acids in addition to CO2, which are also the end products of the citric acid cycle. The researchers think that as biological molecules like enzymes became available, they could have led to the replacement of non-biological molecules in these fundamental reactions to make them more elaborate and efficient.
Linked cycles of oxidative decarboxylation of glyoxylate as protometabolic analogs of the citric acid cycle (open, DOI: 10.1038/s41467-017-02591-0) (DX)
Previously: Diamidophosphate (DAP): "Missing Link" for Abiogenesis? (also by The Scripps Research Institute)
Related: Did Life on Earth Start Due to Meteorites Splashing Into Warm Little Ponds?
Life's First Molecule Was Protein, Not RNA, New Model Suggests
Analysis of Microfossils Finds that Microbial Life Existed at Least 3.5 Billion Years Ago
(Score: -1, Troll) by Anonymous Coward on Tuesday December 19 2017, @02:29PM (2 children)
Humans have been around and have advanced and regressed many times in history. It is no surprise old micro-fossils have been allowed to be displayed to the public. Archeologists have always known that humans and other humanoids have been around for hundreds of millions (billions?) of years, yet the public acknowledgement of that fact is lacking. The system is gradually getting us used to the idea that life has been around a long while. And they do it slowly, over many decades so we will stay in our little bubbles and keep running around chasing our tails in this circus of a planet.
Million-year-old bullets [ancient-code.com]
(Score: 2) by lx on Tuesday December 19 2017, @04:09PM
Bullet holes? My auntie arse! [youtube.com]
(Score: 2, Insightful) by khallow on Tuesday December 19 2017, @07:41PM
If only there were evidence for your assertion. For example, from the linked article, we have this comment:
While it takes a certain amount of integrity to keep contrary comments on an article, we still have no guns or bullets to go with that alleged bullet hole. But we have recovered several alternative tools of the time which could cause such before or after death.
And of course, a million years ago is very different from several hundred million years ago. We know that there were humanoids a million years ago along with crude tool use (assuming generously the fossils are actually a million years old rather than say, 40 years old). We don't have similar evidence for anything back then (including any mammal life forms sufficiently advanced to be humanoid).
Further, it badly strains credulity to assume that a global, industrial civilization could never occur over that vast period of time. Let us keep in mind that the present human civilization has already left evidence of its presence which will still be around hundreds of millions of years from now such as a detectable extinction event, killing off many large land mammals, an enormous heap of artifacts, global architecture, and human skeletons. Some will still be around even if we were to die off right now. And a bit of weird chemistry, such as elevated levels of heavy metals and long-lived radioactive materials from human activities over the past few centuries.
Where's the ten meter layer of a 300 million year old rubbish pile? Where's the fossilized remnant of a building or road? And we've carefully studied any extinction event that we discovered in the fossil record. No sign of civilization in that mess.
(Score: 5, Interesting) by bzipitidoo on Tuesday December 19 2017, @03:53PM (6 children)
Cool, have to update my History of the Earth. One thing, is "primitive" really such a good way to describe the photosynthesis of those times? Especially when they just said it was "surprisingly sophisticated". There was no oxygen in the atmosphere then, and so photosynthesis had to be different.
I cobbled this list together. Here is part of it. Thought of drawing it on the sidewalk in chalk near any high school that was trying to "teach the controversy", but it seems such is rare and fleeting. Anyway, at about 3 million years per 1 m slab of sidewalk, the list is about 1.5 km long. Interruptions for street crossings stretches it to 2 km. Helps give some perspective to just how short our own history is. At about 100 million years per block (33 slabs per block), the extinction of the dinosaurs is less than 1 block from present time and their presence is only 2 blocks long, while the events in this article are 35 blocks away.
Million
years
ago
0 Domination of Homo Sapiens
0.1 ^ Holocene. Old Stone Age.
0.2 V Pleistocene. Homo Sapiens ^^^ evolves in Africa. Homo erectus vvv
...
65.4 ^ Cenozoic. Paleogene. Paleocene. Age of Mammals begins
65.5 V Mezozoic. Cretaceous. K-T Extinction. Age of Dinosaurs ends.
...
252.2 ^ Mesozoic, Triassic. Age of Dinosaurs begins
252.3 V Paleozoic, Permian. Permian-Triassic extinction. The Great Dying
last trilobites go extinct
270 Pangaea supercontinent forms
...
530 1st fish, possible 1st animals on land
The Cambrian Explosion: Multicellular life becomes plentiful and varied.
542 ^ PHANEROZOIC EON. Paleozoic. Cambrian.
v PROTEROZOIC EON. Neoproterozoic. Ediacaran.
...
1650 Oldest known eukaryote fossils
1800 Columbia supercontinent forms
1850 Oceans saturated. Land starts absorbing O2.
possible 1st eukaryotes (single cell lifeform with a nucleus), the 3rd of the 3 domains of life and the type of cell that makes up all plants, animals, and fungi.
2100 v Huronian glaciation.
2400 ^ Huronian glaciation. May have covered entire world. Maybe caused by oxygen removing the greenhouse gas methane from the air
2450 Great Oxygenation Event. Ocean beds saturated. O2 begins to build up in oceans, poisoning anaerobic life.
2500 ^ PROTEROZOIC EON
v ARCHEAN EON
2700 1st steranes, a chemical that is a biomarker for eukaryotes
3200 1st appearance of oxygen in oceans.
3450 1st stromatolites, a "bacteria city"
3460 Oldest certain fossils, of bacteria.
3500 Earliest probable fossils, of cyanobacteria like organisms
3700 Earliest known banded iron formations. O2 waste of anaerobic life rusts the iron
3800 ^ ARCHEAN EON Earliest known biomarkers for life, lipids.
v HADEAN EON v Late Heavy Bombardment
3850 1st indirect evidence of life: Greenland apatite enriched in 12C. Kerogen
3920 ^ Late Heavy Bombardment.
4031 2nd oldest known rocks: Acasta Gniess.
4280 Oldest known rocks: Nuvvuagittuq greenstone belt in Quebec.
4404 Oldest known mineral: Zircons from Jack Hills in W. Australia.
4450 Surface cools enough for liquid water. Rains create the oceans.
4533 ^ HADEAN EON. Collision of Theia & Earth spins Earth so fast that a
day was about 6 hours long, and creates ring of debris that becomes the Moon.
4550 All nearby matter absorbed into Earth, and growth slows.
4560 Earth begins to form.
4567 The sun ignites.
4568 Solar system begins.
(Score: 4, Insightful) by DannyB on Tuesday December 19 2017, @05:05PM (1 child)
I hope you realize that what you suggest flies in the face of science textbooks. In Kansas.
Now if you changed "Million Years Ago" to "Thousand Years Ago", and scaled it out to maybe about 8000 instead of 4568, it would better fit with policies embraced by the current administration's Secretary Of Edumacation appointee.
Why is it so difficult to break a heroine addiction?
(Score: 2, Interesting) by khallow on Tuesday December 19 2017, @07:47PM
Kansas doesn't do that. The Creationists were promptly voted out each time they attempted to undermine teaching of evolution in schools.
(Score: 2) by bob_super on Tuesday December 19 2017, @06:33PM (1 child)
There is still the possibility that Life started on proto-Mars, Proto-Venus, or some other random celestial body which later went splat on Earth. It could have been for 500M years elsewhere before paying us a visit and deciding it liked the place.
(Score: 3, Interesting) by takyon on Tuesday December 19 2017, @06:45PM
It could have come to Earth from some other location *AND* developed 4 billion or more years ago (as soon as the planet had cooled down from Theia/impact events and had surface liquid water).
https://evolution.berkeley.edu/evolibrary/news/170503_cyanobacteria [berkeley.edu]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by HiThere on Tuesday December 19 2017, @06:49PM
Well, given the biological definition of primitive (a trait that hasn't changed from a common ancestral form), the earliest form is by definition primitive, and the earliest known form has to be assumed to be primitive. This says nothing about how "sophisticated" it is. In fact early photosynthesis appears to be been quite sophisticated, but designed to be used in a reducing atmosphere, so few use that primitive form today, because conditions have changed. This isn't a claim that the modern form is more complex (though it is, and that's not a benefit, but the cost of working in an oxidizing environment), but a claim that it's been modified from the ancestral form.
Primitive and sophisticated are not antonyms in biology.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 0) by Anonymous Coward on Tuesday December 19 2017, @08:17PM
The word "primitive" has a specific meaning in evolutionary biology. See https://en.wikipedia.org/wiki/Primitive_(phylogenetics) [wikipedia.org]