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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: 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.