Tag Info

Evolution or (as Darwin called it) "descent with modification" is a theory which explains the origin of the species NOT the origin of life. How the first life arose is completely irrelevant to the theory of evolution. What evolution does explain is how and why we have such variety of life on earth all descending from the same organism. What you're asking ...

We don't know how self-replicating molecules first arose (and probably never will know exactly) but the Earth is large and had 500 million years (i.e. the prebiotic Earth timescale) or so to experiment in organic chemistry. The land-sea interface (such as tidal pools) are a good candidate site since these are areas where high concentrations of organic ...

An interesting take on this question is addressed in Bokov and Steinberg's hypothesis. They have proposed the ribosome has evolved from a short length (~110bp) of RNA that did not have the translational activity that we associate with ribosomes today. Instead this short length of RNA carried out alternative functions on RNA in RNA based life. Then ...

What you are possibly thinking of is large versions of the Miller Urey Experiment where a mixture of reducing gasses carbon dioxide, ammonia, nitrogen and the like are subjected to electrical arcs in a closed flask reaction, resulting in some biological molecules being produced. Opinions have changed - Miller Urey did get the atmosphere wrong and so their ...

Well, what you seem to be suggesting is "Did life evolve twice on Earth?" Your original question has an answer: Probably yes. It's not unlikely to think that the original cell evolved into two different paths and then one went extinct. However, that doesn't address LUCA. If we found fossil evidence of what we thought was LUCA, and then fossil evidence that ...

They teach us in Physics that the entropy of an isolated system is always increasing or at least constant. Then how can an organism be born under these conditions? The sun sends energy to the Earth, allowing for a decrease in entropy on Earth at the expense of the sun's entropy. But when I think about it, all of them assume that there was an ...

It is interesting to note that, in the Wikipedia article, it states that The amino acids were racemic (that is, the chirality of their enantiomers are equally left- and right-handed), indicating that they are not present due to terrestrial contamination". This implies that, if a 'life form' did create these proteins, they are fundamentally quite ...

I think it's fair to say that we don't really know how these more complex organic molecules formed abiotically, but we can say that carbonaceous chondrites - a class of carbon and organic molecule bearing meteorites to which Murchison belongs (specifically CM2) - have experienced at least three distinct chemical histories: In the interstellar medium (ISM) ...

This is an interesting question, particularly considered in the context that Cairns-Smith (1985) even suggested that clays (silicates in solution) may have had some sort of early selection acting on them due to their surface chemistries. However, there are a number of major problems with Silicon. Some are chemical and some are astrophysical in nature. For ...

I would say this is a question that might not be resolved yet. Going back to the earliest days of DNA - a billion years ago - its hard to imagine circular DNA being the first sort to show up. Its speculated that in the transition from RNA world to DNA world, early on each gene had a separate piece of nucleic acid coding for it which would not have been ...

It is hard to give an answer to this question that is not just speculation. We can be reasonably confident that the most recent common ancestor of bacteria and archaea had circular genomes. However, we currently have no way to get any conclusive evidence earlier than that. 3 billion year old DNA doesn't fossilize. So it's just speculation what DNA looked ...

This is an extremely interesting and extremely fundamental question, indeed, and thus far, biologists have failed at coming up with a satisfying answer. We know that all the parts are there, we just don't know how they were arranged, or which ones go where. The question is, in essence, composed of three sub-questions: How did the fundamental building ...

While many point to RNA, or a variant of it, as being the first molecule of "life" very few people know where it came from. Some suggest that it came from outer space because it's uncertain how the material for sugar-phosphate backbones could have developed on earth and that the perhaps these materials found their way here via meteorites. There are several ...

If there are enough nutrients, a unicellular organism will "eat" and grow until it reaches a certain size. Through different mechanisms, it can sense that it is large enough and has enough metabolites to divide. Then, the organism will duplicates its DNA, separate the duplicated DNA and divide. (This is called fission for prokaryotes.) So why does it ...

One important difference is that spontaneous generation is a form of "mechanism" by which a certain species is "born", so it is repeated many times. For such complex organisms this would be part of their "life cycle". It would also need to be a regulated, robust process. Abiogenesis, on the other hand, would create an organism which from that point on does ...

This is a very interesting question but the answer (or as much of he answer as is known) can fill a few books. There are many many signals that control cell division. As a horrible simplification, the cell can be compared to a car parked on a slope with a driver's foot on the brake. If she lifts her foot, the car will roll downhill. In the cell, there are ...