Once upon a time all we had to go on was bones. Comparing them appeared to show a tree of life stretching back to a common ancestor, at least of all animals. Disciplines like embryology helped of course. However, apart from a few woolly traces of bacteria like things in old rocks like the Gunflint Cherts, most early organisms were too small and too fragile to fossilise well. It was a nice idea but the proofs were all a bit shaky.
Enter Molecular Biology. Using the comparative analyses of proteins and nucleic acids, and the rates of change and mutation over time, we have had amazing insights into how all different living organisms are related. Plants, bacteria, fungi, archaea and animals may now be all cross related, which of course means going back in time. Read this article Meet the Parents from Nature Briefings
| The shared forebearer of all life — known as the last universal common ancestor (LUCA) — lived around 4.2 billion years ago, ate carbon dioxide and hydrogen, and produced acetate that might have fed other life. Researchers inferred information about our great-great-grandblob’s genetics and biology by tracing duplicated, lost and mutated genes back up the family tree. LUCA probably possessed an early immune system, too — hinting that it lived in an established ecosystem full of microbes and pathogens.Science | 6 min read Reference: Nature Ecology & Evolution paper |
We would not dare to improve on Nature Briefings, our go-to website for science news. We would however draw your attention to two talking points, as t’were, which have accorded us some pause for considerable thought.
The molecular regression analysis suggests that these things lived about 4.2 billion years ago. Which is incredibly early, as best estimates for the age of the planet come in at around 4.5 billion years[1] That seems a vey short time for so much evolution. What was happening?
The second point is a bit more philosophical. Like one of those fiendish brain teasers about barbers and shaving that Bertrand Russell used to set his brightest students. The authors suspect the LUCA lived in an ecosystem of microbes and pathogens. So was it not ancestor to them too? If not, what was?
[1]https://en.wikipedia.org/wiki/Age_of_Earth
[2]https://en.wikipedia.org/wiki/Barber_paradox
#LUCA #molecular biology #dna #rna #protein #precambian #origin of life #origin of earth
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