Submitted via IRC for takyon
According to a paper released Monday in Nature Ecology & Evolution, the still-unidentified microbe that scientists believe is the ancestor to all cellular life on Earth was born sometime before 3.9 billion years ago. As it turns out, the last universal common ancestor — LUCA for short — emerged even earlier than scientists once believed.
Scientists previously pegged the LUCA's birth to a period 3.5 to 3.8 billion years ago, but the new evidence examined in the study0 suggests it happened one hundred million years earlier. The researchers from the Universities of Bristol and Bath determined the LUCA's new age using the concept of the "molecular clock," which does away with all of the issues with relying on fossils to build Earth's early-life timeline. With early life fossils, there are always older ones waiting to be exposed, which may seem exciting but makes creating an early-life timeline very difficult. The molecular clock, in contrast, uses differences in the genomes of individual species to tell how much time has passed since they shared a common ancestor. The basic idea is that the more mutations two species share, the more time has passed since their evolutionary paths diverged.
The team applied a variant of this approach to some of the oldest existing fossils ever found, hoping they'd reveal when LUCA was born. "We used a relaxed clock framework, which means that the branches across the [evolutionary] tree can have differing rates of evolution," explains first author and University of Bristol Ph.D. candidate Holly Betts to Inverse. Because the differences in age that the molecular clock technique gives are relative, she explains, "you then use fossil calibrations to anchor the tree in real time."
Source: https://www.inverse.com/article/48247-early-life-domain-molecular-clock
0DOI: 10.1038/s41559-018-0644-x
(Score: 5, Insightful) by PartTimeZombie on Wednesday August 22 2018, @03:15AM (3 children)
This is why I think life is reasonably common in the galaxy.
It turns out the planet was pretty inhospitable during that period [wikipedia.org] and yet life began anyway.
I hope to live long enough to see the results of a trip to Enceladus or Europa which might have a chance of discovering life there, and make me even more sure.
Not exactly little green men, but it would be a start.
(Score: 3, Insightful) by mhajicek on Wednesday August 22 2018, @03:45AM
Agreed, I think life is probably common, but spacefaring life may be quite rare.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 3, Informative) by takyon on Wednesday August 22 2018, @09:00AM
If you read the article, the numbers aren't certain, and there would have been a gradual lessening of the impact rate. There's also a graph there that places the earliest life at 4 billion years ago.
If the interval between the chaos of bombardment and the first life forms is (relatively) very short, that's probably great news for life in the galaxy. It could just be stupidly common wherever surface water and other conditions are met.
Enceladus and Europa are a bit sketchier, probably with less ideal conditions for life, and they also wouldn't help us find life in other star systems, since there's no way a telescope would be able to confirm subsurface life on an exoplanet or exomoon. The search for extraterrestrial life will require us to look at the composition of atmospheres or directly image exoplanets to look for obvious signs of life, such as vegetation. That being said, confirming life on Enceladus or Europa would lower the barrier to entry, so to speak, and hint at life on (within) many trillions of worlds in the galaxy. Subsurface oceans appear to be very common in our solar system, and we have a chance to find life from Ceres to Pluto and beyond.
Once we start detecting life or a lack of life on multiple exoplanets, we can extrapolate from the sample and guess how many exoplanets in the galaxy have life. That will help fill out a lot of the Drake equation. And early on, we could look for technological signatures such as atmospheric anomalies that could likely only be caused by industrial activity.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 3, Interesting) by AthanasiusKircher on Wednesday August 22 2018, @11:34PM
Or... it could be that life only emerges in situations exactly like that... we simply don't know.
I'm not trying to be contrarian. Life could be everywhere or it could be basically nowhere. It could form on any planet that had vaguely the right conditions or only on ones with very specific conditions. It could pop up in a few centuries even with the perfect conditions, or it could take millions of years -- and if those conditions change too rapidly, it might not emerge.
All of these are possible. And statistically, until we either have a complete abiogenesis event in a laboratory (which we are NOWHERE near understanding) or until we find life elsewhere, it's all just speculating from one data point.
(And yeah, I've said this before, but I hope life occurs frequently in the universe because it makes things more interesting. But I have no judgment about the likelihood until we have data.)
(Score: 1) by Linatux on Wednesday August 22 2018, @04:41AM
https://phys.org/news/2018-05-gene-survey-reveals-facets-evolution.html [phys.org]
(Score: 0) by Anonymous Coward on Wednesday August 22 2018, @06:43AM (1 child)
They killed my father. So I kill them. It is just.
(Score: 2) by Freeman on Wednesday August 22 2018, @03:29PM
"My name is Inigo Montoya, You Killed my Father! Prepare to Die!"--The Princess Bride, a few times in succession.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 5, Insightful) by The Shire on Wednesday August 22 2018, @01:26PM (5 children)
It drives me crazy to see declaritive article titles that seem to state as fact what is only conjecture and hypothesis. There is no scientific proof to back up this idea, it's just the brainchild of a couple researches who did some statistical analysis using a known flawed dating concept. The "molecular clock" itself is not a proven concept and has many detractors who point out that it relies on a constant rate of mutation. But proteins don't mutate at a constant rate and in actuality have been show to mutate at a greatly increased rate during early evolution and then slow way down as the protein structures become more stable. This means that early in lifes development, such mutations were common and rapid and did not require the hundreds of millions of years the researches are suggesting. Just look at the Cambrian Explosion if you want to see how little constancy there is in molecular evolution. This period saw a massive increase in the rate of diversification. It's like having a watch that sometimes has 10 hours in a day and sometimes 24. You can't rely on it.
But the take away here is that article titles like this implant ideas in peoples minds that are NOT factual. This should be titled "University of Bristol research team suggests life may have evolved earlier than thought". That at least would more accurately convey that this is in no way considered scientific fact by any stretch of the imagination.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @02:55PM (4 children)
Thank you. Someone has to point out what should be obvious. The list of "known facts" that aren't really known facts goes on and on. Astronomy, human prehistory, evolution, global warming, on and on and on . . .
(Score: 1, Informative) by Anonymous Coward on Wednesday August 22 2018, @03:44PM (3 children)
If only the list of your known ignorance didn't go on and on. As a former professional biologist, I know that evolution is a fact.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @03:47PM (1 child)
What you know are some facts, but you can't prove, or reproduce evolution, now can you? Go ahead, evolve us some mastodons. That would go a long way toward convincing all of us that you *really* understand evolution. And, no fair trying to clone a mastodon from some well-preserved DNA. You gotta evolve it from scratch!
(Score: 2) by The Shire on Wednesday August 22 2018, @11:04PM
The evidence for evolution comes from the fossil record and from what we know about how biology works. If you want to see evolution in action, just look into the mirror - you are an example of a biological hybrid between your mother and your father. You have traits from both of them and if any of those traits make you successful in life you may yet pass them on to your own children. If they make you an abject failure, then you're less likely to pass those traits on.
You are all the evidence needed to validate evolution.
(Score: 2) by The Shire on Wednesday August 22 2018, @10:45PM
Evolution has a lot of solid science behind it, there's not a lot of wiggle room for it to be wrong. Climate change on the other hand... that's a political position rather than scientific. Clearly the earths climate has changed radically over it's history, virtually all of which occurred before the human race came into existence. What has happened is you have researches who are commissioned to reach a desired conclusion. As long as funding is available for research that supports the idea that man is causing climate change there will be researchers willing to publish papers to back it up. That's not science, that's commerce.
We've really lost our way when it comes to hard science. Perhaps it's because the things we have yet to learn are just too complex, or perhaps it's because we have a generation of scientists who just don't care and know they won't be called out for poor research. And it's just so easy for reporters to make a punchy "Scientists have discovered XYZ!!!!" headlines that generates revenue despite being a massive misrepresentation of what some paper really means.
We need Carl Sagan back.
(Score: 1, Funny) by Anonymous Coward on Wednesday August 22 2018, @01:56PM (1 child)
My name is LUCA and I live on the second floor
I live upstairs from you
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @02:52PM
Poor battered, abused Luca. No one appreciates her. In fact, we've all but forgotten about her, and she had to be "rediscovered" in TFA.
(Score: 3, Insightful) by inertnet on Wednesday August 22 2018, @02:55PM
I'm having trouble parsing this sentence, because to me it means exactly the opposite of what is suggested: "The basic idea is that the more mutations two species share, the more time has passed since their evolutionary paths diverged."
In fact the more two species differ, the more time has passed.