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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
(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.
The lower I set my standards the more accomplishments I have.
(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]