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558M-year-old fossils identified as oldest known animal
- throwaway2048 8y agoDoes anyone have any details about how they know the bio markers were the result of cholesterol?
- brennebeck 8y agoUp above there’s a link to the paper: https://news.ycombinator.com/item?id=18050904 https://news.ycombinator.com/item?id=18050904
- fifnir 8y agoThe paper: http://science.sciencemag.org/content/361/6408/1246 http://science.sciencemag.org/content/361/6408/1246 Here's a bit more on what they did: >We applied a new approach (17) to test the lichen, protist, and animal hypotheses by studying biomarkers extracted from organically preserved dickinsoniids. Hydrocarbon biomarkers are the molecular fossils of lipids and other biological compounds. Encased in sedimentary rock, biomarkers may retain information about their biological origins for hundreds of millions of years. For instance, hopanes are the hydrocarbon remains of bacterial hopanepolyols, whereas saturated steranes and aromatic steroids are diagenetic products of eukaryotic sterols. The most common sterols of Eukarya possess a cholesteroid, ergosteroid, or stigmasteroid skeleton with 27, 28, or 29 carbon atoms, respectively. These C27 to C29 sterols, distinguished by the alkylation pattern at position C-24 in the sterol side chain, function as membrane modifiers and are widely distributed across extant Eukarya, but their relative abundances can give clues about the source organisms (24).
- stareatgoats 8y agoThe article states that the fossil was "an animal", without further explaining what actually constitutes "an animal", or what characteristics made it unique compared to other organisms at the time (or now for that matter). Maybe it's evident to people in the field, to a layman (like me) the term 'animal' is fairly fuzzy. I went to Wikipedia and found this definition: "With few exceptions, animals consume organic material, breathe oxygen, are able to move, reproduce sexually, and grow from a hollow sphere of cells, the blastula, during embryonic development". So these 'Ediacarans' fall into this category?
- ajross 8y agoThey mean "an animal" in the cladographic sense as being part of the same evolutionary tree as modern animals, and not e.g. lichens or funguses. Specifically, they seem to have detected cholesterol (or some decay product thereof maybe) in the fossil, which is a lipid that only animals make. The identity of the ediacaran fauna has long been controversial. They don't "look like" modern animals (all of whom descend from forms that appeared later, in the cambrian explosion), so they're hard to place. This is a big, big result if it holds up. FWIW: this is the Wikipedia article you want to be reading: https://en.wikipedia.org/wiki/Ediacaran_biota https://en.wikipedia.org/wiki/Ediacaran_biota
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- gwern 8y agoLowe explains it a bit more: http://blogs.sciencemag.org/pipeline/archives/2018/09/21/sitting-there-for-five-hundred-million-years http://blogs.sciencemag.org/pipeline/archives/2018/09/21/sit...
- jasonlotito 8y ago> Now, by identifying the remains of organic matter on newly discovered Ediacaran fossils as ancient cholesterol, the scientists have been able to confirm Dickinsonia was an animal, which makes it the oldest known animal.
- HarryHirsch 8y agoIt's remarkable that the components of the nerve system are very ancient and were all in place in the ur-bilaterian.
- mentos 8y agoIt’s crazy how life just kept building and building on itself. I feel like there were so many opportunities for life to hit a ceiling and never evolve past X stage but yet somehow we broke out.
- ur-whale 8y agoGiven enough starting points, any local optimizer will eventually crawl out of local extrema.
- mcguire 8y agoIf I recall correctly, the division between prokaryotes and eukaryotes took billions of years. Multicellular life was another big step. Everything after that is easy. I remind myself that every morning. :-)
- Emma_Goldman 8y agoI've heard this said many times and believed it, but read to day that the leap from single-cell to multi-cellular organisms happened a dozen or so times independent of each other. That makes it an order of magnitude less improbable, if true.
- gus_massa 8y agoYep, from https://en.wikipedia.org/wiki/Multicellular_organism#Occurrence https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > [...] However, complex multicellular organisms evolved only in six eukaryotic groups: animals, fungi, brown algae, red algae, green algae, and land plants. It evolved repeatedly for Chloroplastida (green algae and land plants), once or twice for animals, once for brown algae, three times in the fungi (chytrids, ascomycetes and basidiomycetes) and perhaps several times for slime molds and red algae.
- solarengineer 8y agoWhen I read such news, I wonder how people reconcile such discoveries backed by scientific validation, with religious texts that provide other timelines and explanations.
- checkyoursudo 8y agoThe few YEC people I've read who actually attempt a reconciliation, rather than just ignore it, tend to disbelieve the dating methodologies.
- ur-whale 8y agoThey don't, or rather don't feel the need to: Each story lives in parts of their brain that are entirely segregated from one another.
- zw123456 8y agoI can give one example explanation. My Father is an evangelical Christian (FYI, I am not, I am an atheist and a science enthusiast). I have asked him this exact same question out of curiosity. Here is the answer he gave (albeit just one perspective). He said "God is so powerful that he can do anything including placing all that evidence there to test our faith". That shuts down any reason to continue a conversation (needless to say this is a topic we generally avoid). Someone once said (not sure the attribution) "never try to reason with someone who has irrational beliefs".
- apocalypstyx 8y agoWhich, of course, leads to an even better double-bind, in that it creates a situation of functional equivalence, because, if God makes the universe look and operate as if it is X billion years old, all inquiry and prediction based upon evidence of that conclusion will, by definition, be accurate. So it may not be the "truth", but from the perspective of living in it, that doesn't matter in the least. And if it only comes up as a matter in the afterlife, (that is, heaven doesn't like the given individual for acting upon the lie) there's another twist in the bind presented: that is God wants the given individual to live, but to do so requires interfacing with the rules of physical reality, which means accepting the predictive power of the "lie".