Certainly there were lipid membranes. Maybe there were spontaneous proteins, maybe there was purely-catalytic RNA.
I guess it's also a matter of line drawing. I'm OK with calling crystals life, for example. One should feel bad about breaking up big ones the same as one should feel bad about killing 150 year old lobsters.
Crystallization is reversible in a thermodynamic sense. You take some granite, melt it, and then cool it (slowly, under pressure), and you have granite again. Is this a phoenix/Jesus-like life and death cycle? Or does life only change forms?
I agree with you generally that 'life' may be gradational. However I think calling crystals 'life' actually removes any meaning whatsoever from the term. If the line isn't somewhere in the neighborhood of viruses and prions then it kinda has to expand to include anything made of matter (and then energy etc.).
While we don't (and don't have to) have a precise definition of 'life', the 'life' gradation needs to branch like a Bezier curve off the x axis at some point for it to be a functional term.
On a similar note, a dead human is "compositionally identical" to a living one, at least for a little while, so I think that's entirely a red herring. :)
What do you mean? Bezier curves are 2d parametric curves, the x and y axes are completely arbitrary...
http://www.bbc.co.uk/earth/story/20160823-the-idea-that-life...
> Cairns-Smith found a more eager audience in science journalists and the popular press. Other scientists showed interest, too: the evolutionary biologist and writer Richard Dawkins discussed the crystals-as-genes hypothesis in his 1986 book The Blind Watchmaker.
[...]
> His aim was to find a system much simpler than modern life, but which had some of the crucial properties of a living system. He found an answer in an unlikely place: clays.
Life is a phase of matter in which the dynamics of information and Turing-complete computation overcome the ordinary dynamics of matter and energy. I am not aware of who originated this idea, but I heard it from Christoph Adami (a researcher in evolutionary information theory). I also recall someone at a conference proposing the term "Turium," for "Turing-complete phase of matter."
Earth just happens to have an environment that contains a large abundance of this phase of matter, much like how stars are full of plasma etc.
In contrast, if you put a plant and its media (soil, air, water) into constant temp and pressure, the plant will continue to grow and change until it exhausts the media. (assuming the temp and pressure are conducive to life) Ultimately plants become their own media by decomposing into soil.
Planet Earth would/should definitely count as alive, especially if it "reproduces" via us terraforming other planets to become like Earth.
RNA and DNA are prone to replicating themselves (with many errors and not efficiently) in a wide variety of situations. It's way more likely that evolution selected those molecules for efficiency than that some complex life appeared without some transferable data storage.
Obviously, any RNA or DNA molecule can serve as a template for the polymerization of another nucleic acid molecule.
However the polymerization cannot proceed spontaneously. The nucleotides polymerize by condensation, i.e. by releasing water.
It should be obvious that such a reaction cannot be spontaneous when the molecules are already surrounded by water. You need some molecule able to extract the water from the nucleotides, for example an acid anhydride, like ATP.
That anhydride must have also been produced by water extraction and in the water environment you need an energy source for that.
So if you will complete the analysis you will reach the conclusion that you need an existing living being for the replication, no replication can occur otherwise.
Obviously, in a lab you can yourself substitute the role of that living being, by providing adequate supplies of monomers and of energy sources, so you can replicate nucleic acids in abiotic conditions. Nevertheless, that could not happen in natural conditions.
When RNA or any other kind of genetic material first appeared, the first thing that must have been possible to do with it was to copy it, a.k.a. to replicate it.
If the genetic material was used first to do anything useful, e.g. to control protein synthesis or to catalyze directly any useful reaction, that genetic material would have disappeared immediately, because it could not be replicated.
So the first genetic material must have been able of being replicated without doing any useful function, therefore is was actually an RNA virus.
The useful functions must have appeared later and then the genetic material was integrated as an essential part of the living beings, allowing a much faster evolution towards levels of complexity that would have been impossible to reach without having a genetic material.
To be able to replicate the first genetic material, there must have already existed some life forms able to exploit an energy source to reproduce themselves.
You have noticed a correct analogy, exactly like the control automaton of a CPU, which can be either hard-wired, having a dedicated structure that cannot be easily changed to perform other functions, or it can be microprogrammed, using a control memory, whose content can be easily rewritten to implement a very different CPU, a self-reproducing living being can use genetic material, in which case it can easily evolve into a different living being, or it may use no genetic material, but consist, like how it seems to be said in Gánti's work, of which I was not aware until now, by a cycle of reactions, where in each reaction some cell component assembles another cell component, until the last component, which assembles the first component.
Such a living being, without a genetic material, could not evolve easily, because almost any change would have damaged the cycle of reactions, most likely stopping the reproduction.
Regarding RNA, before the first RNA molecule was ever assembled, the existing life forms must have been using ATP and the other nucleotides as dehydrating agents able to condense smaller molecules into larger molecules, e.g. for creating peptide bonds.
Therefore ATP (with some of it current uses) is certainly older than RNA.
The polymerization of nucleotides into RNA must have been initially an undesirable side reaction consuming the useful nucleotides.
1. It must be able to store any random sequence of symbols belonging to a certain set (e.g. any possible sequence of bases in the case of nucleic acids).
2. There must be a way to make identical copies of it (e.g. nucleic acid replication).
(the previous 2 properties are true both for its own genetic material and for a foreign virus that does not have any use for a living being)
3. There must be a way to use the stored sequence of symbols to direct some process that is useful for a living being.
(for nucleic acids, the better known useful processes are protein synthesis and the synthesis of certain kinds of useful by itself RNA, but there are also some other poorly understood functions of most of the "junk" DNA)
“Life” as it were, is a concept invented with either the intention of distinguishing “us” from the rocks around ourselves, or, if you’re being slightly less charitable, giving “us” a way to insult the, um, others.
Sure, drawing some line in the sand between mice and boulders is a great idea, but it’s a pretty arbitrary one, especially if you have to strap a bunch of historical baggage on it.
This grand debate is almost as fun as what-constitutes-a-planet. We should do that one again.
Hence the current astrophysical paradigm where we now have planets and dwarf planets (which aren't planets).
When we do finally agree on a mathematically rigorous definition of life, it will seem obvious in retrospect and scientists will kick philosophers off the field, just like they did with previous subjects like the composition of matter, the movement of heavenly bodies, etc.
Every scientific topic has to go through a messy definition phase before its study can be properly organized. People studied heat and cold for a long time before they really knew what they were, for example.
(Also by phlogiston's time, philosophers and natural philosophers = physicists had already pretty much split.)
Or in other words, say at some point we discover aliens in a distance galaxy. Would we be cousins? Are there visualizations that show what that kind of family tree would look like?
I am a neophyte in this area but I'm sure there's a lot of good research out there.
And that's just the broad strokes, trees would be the details.
It's worth noting also that even only considering life on Earth that we already know about, the "tree of life" is already kind of a broken abstraction. Consider bacteria that are able to share genetic material without an ancestor relationship for instance, or closer to home even viruses that infect humans or any other kind of mammals. They affect our genetics in ways the tree doesn't/can't capture.
[0] https://physicsworld.com/a/amino-acid-detected-in-space/
Actually lipid bilayers are extremely complicated as they have to filter what gets into the cell and what doesn't, as well as what might leave it. Earlier systems might have done without them and instead attached everything onto long chain like structures... You know like a keychain. Both RNA and Proteins are long chains so maybe that's how they evolved.
https://en.m.wikipedia.org/wiki/Von_Neumann_cellular_automat...
> According to the chemoton model, life should basically, but of necessity, have an autocatalytic subsystem consisting of metabolism and a replication process, and a membrane enclosing these functions.
also
>A single chemical reaction is said to be autocatalytic if one of the reaction products is also a catalyst for the same or a coupled reaction
I was also going to point out the irony that the news article cares more about the man rather than the discovery of the origins of life.
There is no news here. This is just the same speculation that has been made thousands of times before for decades. Of course we can make big molecules from small ones in a lab. Of course life has to reproduce, metabolize and have a boundary from the environment. Pointing this out is not "the key to the origins of life". It is still an interesting topic, but why cant national geographic discuss these things honestly?
And of course that this is the key to the origins of life - how could we possibly make progress on this question without understanding this first?
And someone had to be the first to point this out. Which Tibor Gánti did in 1971 & 1974.
>Some consider this model a significant contribution to origin of life as it provides a philosophy of evolutionary units.[4]
https://en.m.wikipedia.org/wiki/Chemoton
Read the wiki. Its just describing what a cell is and putting the word "abstract" in front of everything. It makes no prediction, it produced no results. Evidently not everyone considers it a significant contribution.
This is not self evident. Maybe this is the news?
I am not sure, what are you saying?
> organisms are open systems that maintain homeostasis, are composed of cells...
https://en.m.wikipedia.org/wiki/Life
Cell by definition have a boundary called the cell membrane.
>Cells consist of cytoplasm enclosed within a membrane...
Primitive proto-life has little moral value, just as vegans eat plants, hypothetical super-vegans only eat blue-green bacteria, and hypothetical hyper-vegans have a 500 year deadline to be electrically powered.
I don't believe in a hard barrier between life and non life, so any discrete moral function would be non-computable, and therefore I reject it outright.
That's not a problem. There can be insane theological and ethical consequences for everyone else.
If we take that life plausibly "started" as as one single-celled individual who then "reproduced" through cell division (let's call him Luca), then he's effectively never died - in the same way that we consider ourselves to have not died despite regularly cycling tissues and cells.
All life as we know it, if viewed like that, is one organism whose chain of cell division has never been broken as he's grown over billions of years. Variation between those cells (kingdoms, species, plant / animal etc) become like skin, hair and brain / liver cells within the human body.
It would be like taking a runner grass or banana tree and trying to draw a line around true individuals.
If we created life outside of that unbroken chain of cell division, we would have created something which is definitely "other than Luca" and that feels philosophically significant.
So no major consequences.
"The Revolutionary Phenotype is a science book that brings us four billion years into the past, when the first living molecules showed up on Planet Earth. Unlike what was previously thought, we learn that DNA-based life did not emerge from random events in a primordial soup. Indeed, the first molecules of DNA were fabricated by a previous life form. By describing the fascinating events referred to as Phenotypic Revolutions, this book provides a dire warning to humanity: if humans continue to play with their own genes, we will be the next life form to fall to our own creation. "I am VERY impressed with this book—very important topic very well treated." - Robert Trivers"
https://www.amazon.com/Revolutionary-Phenotype-amazing-story...
fyi: I'm not the author
