Earliest Life: What Was the First Life on Earth Like? How We Study LUCA | GEO GIRL

This video is all about our guesses as to what metabolic pathway(s) the earliest life on Earth might have used! We start by going through the possibilities like photosynthesis vs chemosynthesis, then assuming a hydrothermal vent life origin, we moved on to discuss the possible chemotrophic pathways: chemoautotrophy (use inorganic carbon for metabolism) vs. chemoheterotrophy (use organic carbon for metabolism). We actually don't know for sure which one is first, but we assume a chemoautotrophic start for the rest of the discussion. We then discuss which chemolithoautotrophic pathways are most likely the earliest to evolve (both elemental sulfur reduction and sulfate reduction are possible, with the combination of Fe(III) reduction in some cases, and methane production by methanogenesis is the other main possible pathway). We further discuss the potential for these pathways to have evolved early by looking at the deepest-branching bacteria and archaea. Deep branching bacteria have the ability to reduce oxygen, nitrate, sulfur species, or iron using hydrogen (H2) as an electron donor. But we cannot pinpoint the first bacterial metabolism because lateral gene transfer (or horizontal gene transfer) prevents us from piecing together a perfect evolutionary tree. Deep branching archaea have the ability to either reduce elemental sulfur or reduce carbon dioxide to produce methane. However, sulfate reduction is present in both deep branching bacteria and some archaea, so was our last universal common ancestor (LUCA) a sulfate reducer? Again, lateral gene transfer prevents us from knowing for sure. Lastly, we discuss the first fermenting and respiring organisms. These chemoheterotrophs had to evolve to eat the organic carbon produced by the earlier chemoautotrophs.
References: Geomicrobiology: amzn.to/2WAloTR
Biology of Microorganisms: amzn.to/3kQqIuD
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, and donate to support the channel if you'd like!)
0:00 what this video covers
0:53 life's origins
2:26 was phototrophy or chemotrophy first?
4:07 was autotrophy or heterotrophy first?
5:08 first metabolism on Earth
6:54 how we study LUCA
7:20 deepest branching bacteria
9:32 lateral gene transfer
10:29 deepest branching archaea
12:32 was LUCA a sulfate reducing microbe?
14:04 when did fermentation evolve?
14:50 when did respiration evolve?
16:31 evolution of macroorganisms
18:00 references & upcoming videos!
19:02 my cat ;)
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Disclaimer: Links included in this description might be affiliate links. If you purchase a product or service with the links that I provide I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel so I can continue to provide you with free content each week! And as always, let me know your topic suggestions in the comments down below!

[@GEOGIRL]

A couple notes: 1) Every time I say that O2 wasn't abundant on early earth because "photosynthesis hadn't yet evolved" I mean to say "oxygenic photosynthesis" because technically anoxygenic phototrophs may have evolved by then. 2) I made this video over a month ago and since then I've had conversations with many of you about the origin of life and I now plan to make a future video or videos about other possible environments for the origin of life (such as the warm little pond, underground clay layers, other planets, etc) instead of just hydrothermal vents. The reason I've made my 'Life Origins' video and this video assuming a hydrothermal vent origin is because the references I am using focus on that. But I promise I will find more references and make new content comparing/contrasting all of these hypotheses ;) Thanks to all of you who gave me that idea, I think it's excellent! :D

[@princeshukla7661]

That's cool 😎😌

[@ellenmcgowen]

I wonder whether it is really necessary to find one environment that the entire "origin of life" took place in, all the way from prebiotic chemistry to LUCA. Why not one environment to get RNA world started and a different one for evolving more advanced metabolisms and translation? RNA replication could have originated in one environment and then radiated to additional environments. It might be easier to think about this if we knew what function the "pre-protoribosome" had in RNA world...

[@GEOGIRL]

@@ellenmcgowen So true! Good point! I guess I mean which environment did the first living (self-replicating) thing evolve in rather than LUCA because LUCA could've evolved later in a different environment. I imagine it was a snowball event once life actually took hold. And I also imagine that the components that make up life could've come from anywhere really... I don't know, but I think it's good to think about, thanks for point that out ;)

[@caspasesumo]

Nice! My biggest problem with abiogenesis occurring in hydrothermal vents is that these vents are likely to be in an aqueous environment. I think you have to invoke a surface catalyst or other concentrating environment to get biochemistry started. Oceanic vents would lead to massive dilution of reactants. This is why I prefer warm ponds going through wet/dry cycles since one could imagine nice catalytic surfaces to get things going. subsequently, early life could then "migrate" to hydrothermal vents to establish the ecosystems you propose.

[@JoesFirewoodVideos]

Thanks for clarifying doctor

[@PraiseDog]

I am very interested in the subject matter, but also I just find her delightful to watch and listen to. There are some channels that have subject matter I am interested in, but they have disappointed me because I just can't stand the person or people presenting it, they are annoying for one reason or another. But Geo GIrl is never annoying, she is very comfortable to listen to. I appreciate that she covers a lot of material and presents it in a way that facilitates memorization.

[@GEOGIRL]

Oh, thank you very much! I am so glad you find me confrotable to listen to. :) I cringe at my own videos because I hate watching/listening to myself haha, but I am so glad you don't have that reaction hahaha ;)

[@RT710.]

I absolutely LOVE how these big questions force us to combine our knowledge from so many (seemingly) different fields of study! It really puts into perspective how interconnected and related all things are. Thank you for this video!

[@GEOGIRL]

Couldn't agree more! Thanks for the comment & support ;)

[@ellenmcgowen]

Fantastic video!!! The Konhauser book was in my stack for future reading but is going to the top of the list. And please tell your cat that geomicrobiology is NOT boring! :-)

[@GEOGIRL]

Thank you!! And of course, I'll let her know but not sure if she'll listen haha! 😂

[@michaeleisenberg7867]

Hello Geo Girl! It's hot as heck in Las Vegas. July 19th. I'm throwing two tennis balls into the pool for my two English goldens--Chuck & Berrt. Get rid of at least some of their shedding . These first three videos are top notch. You've compiled the best we know for the beginning of it all. They should be placed back to back to back in at least two of your playlists. They're awesome! You're awesome! 1. Prebiotic Life. 2. Origins of life. 3. Earliest life. It's all such an enigma. What happened before the first cell? Here are at least two paradoxes that no one has the answer to. 1. Which came first, DNA or DNA polymerase? 2. Which came first, ATP or proteins that use ATP? I absolutely love your discussion about early electron donors, spitting out a proton, a proton gradient, and ATP synthase. Maybe it happene d in the bottom of the ocean? Regardless, we're all here because of it. And in a later video I guess it will be the cockroaches 😘.

[@rursus8354]

Why do you only have 171 likes? Considering that you have 16200 subscribers, something like 3000 would be more realistic, considering how accurate these videos are.

[@GEOGIRL]

Haha I don't think all my subscribers watch every video ;) But I really appreciate those that do, Thanks for watching and commenting! :D

[@oker59]

The idea that the Dinosaurs(outside of birds) went extinct due to an asteroid collision and life at the ocean vents not needing light were ideas that inspired me when young, in the 1980s.

[@GEOGIRL]

They continue to inspire me as well!

[@JoesFirewoodVideos]

My Wednesday late night entertainment has arrived. Thank you so much Rachel. I ❤️ GEO GIRL!

[@GEOGIRL]

Of course, thank you for watching & commenting as always, Joe! :D

[@platzhirsch4275]

In discussing this issue i think enzymes are a very good topic for examination. A scientist by the Name of Fred Hoyle (An Astronomer that spoke much on biological science) had written a piece published in New Scientist that stated a fact that 2000 different and complex enzymes are necessary for a living organism to exist. He also stated that a random shuffling process could not form a single one of these enzymes in even 20 billion years! But did not stop there. "I don't know how long it is going to be before Astronomers generally recognize that the arrangement of not even one among the many thousands of biopolymers on which life depends could have arrived via natural processes here on Earth. Astronomers will have little difficulty in understanding this because they will be assured by biologists that it is not so; the Biologist having been assured in turn by others that it is not so. The others are a group of persons who believe, quite openly, in mathematical miracles. "They advocate the belief that, tucked away in nature, outside of normal physics, there is a law which performs miracles (providing those miracles are in aid of natural biological development). This curious situation sits oddly upon a profession that for a long time has been dedicated to coming up with logical explanations..." "The modern miracle workers are always found to be living in the twilight fringes of [the two laws of] thermodynamics." *Fred Hoyle, "The Big Bang in Astronomy," New Scientist, November 19, 1981. Pages 521-527* And this one by G.R. Taylor: "The fundamental objection to all of these [evolutionary] theories is that they involve raising oneself by one's own bootstraps. You cannot make DNA without enzymes, which are proteins. It's a chicken and egg situation. That a suitable enzyme should have cropped up by chance (an evolutionist said it, CHANCE), even given a long period, is implausible, considering the complexity of such molecules. And cannot have been a long time [in which to do it]." *The Great Evolution Mystery (1983) * The other issue is that enzyme systems do not work in the body until they are all present. Michael Pitman, in his book, Adam and Evolution, written in 1984, says this about enzymologists Malcolm Dixon: "Dixon confesses that he cannot see how such a system could ever have originated spontaneously. The main difficulty is that an enzyme system does not work at all until it is complete, or nearly so. Another problem is the question of how enzymes appear without pre-existing enzymes to make them. 'The association between enzymes and life,' Dixon writes, 'is so intimate that the problem of the origin of life itself is largely that of the origin of the enzymes.'" In 1964, Malcolm Dixon and Edwin Webb, on page 667 of the work, "Enzymes", a reference work, mention to fellow scientists that; in order to get the necessary amino acids in close proximity to form a single protein molecule, a total volume of amino acid solution equal to 10^50 times the volume of the Earth would be needed. Just imagine then what it would take for a single hemoglobin molecule, which has 574 amino acids! In their book, "Introduction to Protein Chemistry", S.W. Fox and J.F. Foster explain the immensity of the issue. "First, large amounts of the 20 basic types of protein molecules would be needed. In order to be successful, enough random protein molecules would be needed to fill a volume equal to 10^512 times the volume of our entire known universe! That entire space would have to be packed solid with protein molecules. All of them would have to be left-handed." It goes on to show that it is only then that random chance could possibly produce the right sequence for just one hemoglobin molecule! now expand that further to cells. the human cerebral cortex has ten billion cells. Do we really know what we are talking about when assuming these processes arise without intelligence? So, realistically, where does that leave us?

[@Smilo-the-Sabertooth]

Oh yes!!! The origins of how life came to be on Earth, a really fascinating topic that I’m really excited about. I’m really looking forward to more interesting videos about topics like this. As always, it’s such a pleasure for me to learn with you and continue to give you my full support. Keep it up with the fantastic work my friend. 😊❤😉👍

[@GEOGIRL]

SO glad to hear you like this topic! It is one of my favorites to talk about, so I will take that as permission to do more videos on it ;D

[@Smilo-the-Sabertooth]

@@GEOGIRL Excellent my friend. I can’t wait, I’m more excited than ever to learn with you and I’m really looking forward to more of your incredibly fascinating videos. You’re amazing. ❤👍

[@adquidorator3374]

IMO, the first organisms used an energy metabolism that no longer exists that I like to call D.E.P.H. (dissimilatory energetic phosphate hydrolysis). Modern life uses polyphosphates as its' energy currency and have to expend energy to replenish them. But during the Hadean and early Archean, large qunatities of meteorites would have delivered a mineral called "Schreibersite" that will release poly-phosphates when it reacts with water. These could have then been utilized by the first oranisms which would have released orthophosphate with no means to polymerize it.

[@lexzbuddy]

I find corals really interesting. They've been around a long time, some largely unchanged. The more I learn about them the more I want to learn about them. I really can't get enough about them. Just saying 😊

[@vinniepeterss]

❤❤ love it

[@while.coyote]

It's so wild to think some chemicals started fizzing together and for the next four billion years the reaction just kept going and never stopped, and now that very same reaction studies it's own origins and makes (and watches) videos about itself.

[@GEOGIRL]

Haha wow I never thought about it that way but you're right! How trippy lol

[@mi4208]

Great work please make one video on Hydrogeology

[@GEOGIRL]

Thanks for the suggestion, I will work on it :) It may take a little while because that is out of my expertise, but I will for sure work on it!

[@mi4208]

@@GEOGIRL No problem 👍

[@colubrinedeucecreative]

fascinating! You held my intertest that whole time! And actually regular fossils are kinda boring, to actually know what people look for for early life fossils, well that is where it is at! Not sure why but yeah, fossils are pretty boring unless fairly large or opalized

[@GEOGIRL]

So glad to hear you enjoyed it! :D And yes, I agree, fossils can be boring if not opalized or pyritized or just something really rare ;) Thanks so much for the comment!

[@platzhirsch4275]

It so happens that we tend to look at these discussions to casual. The simplest life forms are far away from being simple and thus it might be nicely entertaining for a casual discussion of the topic but I'm afraid leads to wrong assumptions. The proteins needed for the simplest life forms are very complicated biochemical structures for which we are far away from understanding how these could ever have evolved. proteins of this type, with complex functions and chemistry, with complex regulation, with many protein-protein interactions, proteins that bind cofactors in preciase orientations and distances, do not evolve at such high rates to give rise to life in the required timeframe. The problem is that if we make necessary evolution time smaller, then even higher rates would be required at the point of duplication, which however is chemistry wise impossible. Ribosomes necessary for protein synthesis defy all serious theory how they could have formed and prokaryotic life or cyanobacteria are already such complicated bacteria life forms often depending on a remarkable sophisticated biochemical processes called photosynthesis, that there is no serious theory as to how all that could have evolved. The Ribosome itself far to complex in structure, photosynthesis a highly complicated biochemical pathway we can't even reproduce today. the biggest problem however is the origin of the DNA and the INFORMATION inside that very complex protein structure in a bacteria. The DNA already has all the information controlling all aspects of protein syntheses and the biochemical pathway for photosynthesis. How did that very advanced biochemical information get into the DNA ? We're not even talking of the duplication of this information which is crazy complex. It seems impossible that proteins of this sort of complexity ( comparable to modern Software) could arise. Looking at the whole issue in detail brings up so many questions that I feel such an analysis creates the wrong impression I'm afraid. One could easily hypothesize that the process emerged from oxidative photochemical reactions during abiogenesis that could have resulted in the oxidation of water at a very early stage during the establishment of bioenergetics. But still, when studying photosynthesis it seems impossible to assume such an advanced biochemical process could ever "evole" in terms of abiogenesis. There is no pathway for anorganic chemistry coming up with such pathways especially as the proteins involved are so extremely complex that we see no realistic pathway for any such protein to arise. I'm aware of some scientists claiming otherwise but this sounds more like deception, scientific narcissistism etc. It's nor genuine especially not for those familiar with the necessary biochemistry involved.

[@royaleblizzard2460]

Cool 😉

[@GEOGIRL]

Thanks! Glad you liked it ;)

[@charlesdye8367]

So....um... thank you? You made me want to learn way too many things. :) Awesome stuff

[@GEOGIRL]

OMG This comment is the best I could ever receive, thank you! I am so glad I inspired you to learn more things ;D

[@charlesdye8367]

@@GEOGIRL seriously keep it up. Going to try and get my 16 year old daughter to watch.

[@charlesdye8367]

Which video do you recommend she start with? She's more into biology and math.

[@GEOGIRL]

@@charlesdye8367 Unfortunately, I don't talk much about math, but I do have a lot of bio-focused videos! In fact, I have an enitre geobiology playlist: kzbin.info/aero/PL69bBhmsrgfs2GuFioWkJpO3P_aTjSIkE so she can start there, or if you think she'd like to see more about biology through Earth's history, she can check out the Earth history playlist: kzbin.info/aero/PL69bBhmsrgfvxffzspQPyWJtvs20f8v7e where I talk about more 'popular' biological topics like dinosaurs, extinction events, etc. rather than the details associated with microbial-rock interactions like the geobio playlist. Anyway, I'd start with those and she can just cherry pick the topics she thinks she'll be interested in ;D

[@charlesdye8367]

@@GEOGIRL and the main thing is, you're a role model. I want her to see you and hear you.

[@Hopamptube]

Consider the following Qur’anic verse: “Do not the unbelievers see that the heavens and the earth were joined together (as one unit of creation), before We clove them asunder? We made from water every living thing. Will they not then believe?” (Al-Qur’an 21:30]m) "With power did We construct the heaven. Verily, We are Able to extend the vastness of space thereof." (Al-Qur’an 51:47) “We made from water every living thing” (Al-Qur’an 21:30).

[@GoToGuy222]

Your opinion on Thomas gold?

[@princeshukla7661]

Hello geo girl thank you so much Love from INDIA

[@GEOGIRL]

Thank you so much for your never-ending support and consistent comments ;)

[@princeshukla7661]

@@GEOGIRL thank you so much for your reply

[@ramchauhan5238]

Excellent video mam..🙃🙃👏👏👍👌👌

[@GEOGIRL]

Thank you so much! Glad you liked it :D

[@ramchauhan5238]

@@GEOGIRL 😊😊

[@Exprovider-Cahit]

What do you think of RNA world or XNA world theories? And which came first: Metabolism or RNA? I want to hear your opinions

[@GEOGIRL]

Unfortunately, I have no ground to stand on when it comes to these topics, I mean I can teach what other people have hypothesized, but that is all I know haha, this is not my area of expertise ;) I am sorry my answer is not more exciting, what are your opinions about it? :D

[@Exprovider-Cahit]

@@GEOGIRL it looks like Rna world theory has more potential than the others. But i dont think i know these topics better than you :D thats why i asked you.

[@thesjkexperience]

Sweet kitty

[@cerberaodollam]

How about the montmorillonite clay + RNA thing?

[@GEOGIRL]

Ahhh! That's a great question and so funny you asked now because I am actually currently working on a video about the clay origin of life hypothesis! :D

[@cerberaodollam]

@@GEOGIRL cool!

[@nebulan]

😻

[@JasonKale]

So everything is down to the electrons?

[@GEOGIRL]

Hahaha yep, always lol

[@JasonKale]

@@GEOGIRL haha

[@platzhirsch4275]

Maybe one of the most striking molecular machines in a cell us the ATP Synthase. The whole ATP synthase machine with individually manufactured protein subunits each labelled with Greek letters. H+ ions (protons) flow through a special tunnel in ATP synthase. This induces mechanical motion, forcing the axle and base to spin together like a turbine. Nearly 100% of the spinning momentum is converted to chemical energy in the formation of ATP molecules! Three ATPs are produced for every 10 protons. Life depends on an incredible enzyme called ATP synthase, the world’s tiniest rotary motor. This tiny protein complex makes an energy-rich compound, ATP (adenosine triphosphate). Each of the human body’s 14 trillion cells performs this reaction about a million times per minute. Over half a body weight of ATP is made and consumed every day! All living things need to make ATP, often called the “energy currency of life”. ATP is a small molecule with a big job: to provide immediately usable energy for cellular machines. ATP-driven protein machines power almost everything that goes on inside living cells, including manufacturing DNA, RNA, and proteins, clean-up of debris, and transporting chemicals into, out of, and within cells. Other fuel sources will not power these cellular protein machines for the same reasons that oil, wind, or sunlight will not power a gasoline engine. The ingeniously designed nano bio- technology called ATP Synthase is clearly a machine. Its easy to casually write "it evolved" but are you really doing the issue justice ⚖️ 🤔? Definitely no as to casually write it "evolved" might satisfy casual O Level students and might supply narcissistic supply to whoever needs some casual clapping 👏 but whoever understands the topic at hand should notice that such an advanced biochemical nano machine can't just "evolve" and we have no idea how this machine came into existence hence its very wrong to casually conclude "it evolved". Thank you for allowing me to comment despite the fact I guess you don't like my comment but maybe it will make you think about it more and it will help you understand that life is very precious and didnt just casually "evolve".....

[@whiskeytango9769]

Therefore...God did it...right?

[@platzhirsch4275]

@@whiskeytango9769 "...we have no idea how this machine came into existence......"

[@whiskeytango9769]

@@platzhirsch4275 Perhaps, but it's a safe bet that it did actually involve an evolutionary process, even if we do not presently understand all the details. To say that we "have no idea" is very likely false.

[@platzhirsch4275]

@@whiskeytango9769 as I explained above: we certainly don't have a clue how these molecular machines and the information in the DNA and the coding in the RNA could evolve. Whoever understands these biochemical engineering machines and processes should admit that. To say " we don't understand it fully" is a gross understatement. We don't have a clue. As said as just one example I suggest the analysis of the ATP SYNTHASE MACHINE. Anyone saying this amazing machine could evolve certainly doesn't have scientific reasons to say that as there is no single proof for that hypothesis

[@whiskeytango9769]

@@platzhirsch4275 Except that we know that evolution works. So, to hypothesize that these machines also evolved is perfectly reasonable...as a hypothesis. The more ridiculous claim is to say that it could not have evolved when we have demonstrated how powerful evolution really is at creating new and novel function.

[@jwfcp]

Kitty!

[@GEOGIRL]

😻😸

[@johnnywoodstock]

For or against, I would LOVE to see YOUR take on young earth creationism. (A controversial topic in the world of geology and Paleontology) It's different, unorthodox, and it's an interesting perspective that actually holds a surprising amount of weight when tested. In my opinion at least 😁

[@GEOGIRL]

I appreciate the suggestion! However, I just don't feel as though I am knowledgeable enough about that topic to speak on it. I try to only speak on topics I have personally spent a lot of time studying and researching and I don't study that. (& just to be clear, I do not at all judge anyone for studying or believing in creationism of any sort, it is just something I do not think I'd make a good video on, that's all ;) Thanks again for the comment and suggestion though!

[@johnnywoodstock]

@@GEOGIRL oh yes, perfectly understandable. They're not really allowed to teach creationism in schools anymore I believe. However a video on the different types of dating (radiometric ,carbon-14, Argon 40) would be nice and informative

[@GEOGIRL]

@@johnnywoodstock Great, thanks for the feedback, I will work on the dating video ;)

[@silknfeathers]

@@GEOGIRL Why not judge someone for studying creationism? Would you suggest crystal chi energy is a relevant topic for scientific discussion? Great video , btw...

[@GEOGIRL]

@@silknfeathers Because I am not here to judge, just to educate ;)

[@cerberaodollam]

Does early life have to be that hot? And does that moon with all the water on it get that hot?

[@GEOGIRL]

Nope, there are other hypotheses about early life and life's origins in much lower temperature conditions. And yes, based on recent models there are likely hydrothermal vents on Enceladus as well as Europa (moons with liquid water oceans and potentially life). ;)

[@cerberaodollam]

@@GEOGIRL woohoo, aliens. I hope we don't accidentally destroy them when we get there, like we did with native wildlife in like Australia and such.

[@oliverweeweepie3132]

Hey I thought I was your cat!!!!

[@GEOGIRL]

You are Ollie ;)

[@oliverweeweepie3132]

Ok❤️ you can love other cats, but I’m you big boy ❤️

[@GEOGIRL]

@@oliverweeweepie3132 Haha, people are going to think this comment thread is so weird lol ❤

[@JoesFirewoodVideos]

What’s my prize? During the middle of the video I actually thought about asking you if you’re a cat person or a dog person. I see you’re a cat person and so am I. My cat Missy Grey will be turning 13 in April. She’s in bed with me right now.

[@GEOGIRL]

Yes! Cats are the best! But I also love dogs ;)

[@lethargogpeterson4083]

Agree that the prize at the end of the video was excellent :-)

[@velikerimov9703]

Hi.GeoGirl, please subtitre :))

[@GEOGIRL]

Unfortunately this video and the prebiotic video are glitching when I try to add subtitles, it never happened to me before so I will contact KZbin to try and fix it, just may take a bit longer, sorry!

[@velikerimov9703]

@@GEOGIRL Understand, thank you very much GeoGirl

[@usamadanish8804]

🇵🇰🇵🇰🇵🇰🇵🇰🇵🇰🇵🇰🇵🇰

[@platzhirsch4275]

Finally I would like to summarize some basic chemistry ⚗️ issues : How could ammonia (NH3), the precursor for amino acid synthesis, have accumulated on prebiotic earth, if the lifetime of ammonia would be short because of its photochemical dissociation? How could prebiotic events have delivered organosulfur compounds required for a few amino acids used in life, if in nature sulfur exists only in its most oxidized form (sulfate or SO4), and only some unique groups of procaryotes mediate the reduction of SO4 to its most reduced state (sulfide or H2S)? How did unguided stochastic coincidence select the right amongst over 500 that occur naturally on earth? How was the concomitant synthesis of undesired or irrelevant by-products avoided? How were bifunctional monomers, that is, molecules with two functional groups, so they combine with two others selected, and unifunctional monomers (with only one functional group) sorted out? How did prebiotic events produce the twenty amino acids used in life? Eight proteinogenic amino acids were never abiotically synthesized under prebiotic conditions. How did a prebiotic synthesis of biological amino acids avoid the concomitant synthesis of undesired or irrelevant by-products? How could achiral precursors of amino acids have produced and concentrated only left-handed amino acids? ( The homochirality problem ) How did the transition from prebiotic enantiomer selection to the enzymatic reaction of transamination occur that had to be extant when cellular self-replication and life began? How would natural causes have selected twenty, and not more or less amino acids to make proteins? How did natural events have foreknowledge that the selected amino acids are best suited to enable the formation of soluble structures with close-packed cores, allowing the presence of ordered binding pockets inside proteins? How did nature "kHow could ammonia (NH3), the precursor for amino acid synthesis, have accumulated on prebiotic earth, if the lifetime of ammonia would be short because of its photochemical dissociation? How could prebiotic events have delivered organosulfur compounds required in a few amino acids used in life, if in nature sulfur exists only in its most oxidized form (sulfate or SO4), and only some unique groups of procaryotes mediate the reduction of SO4 to its most reduced state (sulfide or H2S)? How was the concomitant synthesis of undesired or irrelevant by-products avoided? How were bifunctional monomers, that is, molecules with two functional groups so they combine with two others selected, and unifunctional monomers (with only one functional group) sorted out? How did prebiotic events produce the twenty amino acids used in life? Eight proteinogenic amino acids were never abiotically synthesized under prebiotic conditions. How did a prebiotic synthesis of biological amino acids avoid the concomitant synthesis of undesired or irrelevant by-products? How could achiral precursors of amino acids have produced and concentrated only left-handed amino acids? (The homochirality problem) How did the transition from prebiotic enantiomer selection to the enzymatic reaction of transamination occur that had to be extant when cellular self-replication and life began? How would natural causes have selected twenty, and not more or less amino acids to make proteins? How did natural events have foreknowledge that the selected amino acids are best suited to enable the formation of soluble structures with close-packed cores, allowing the presence of ordered binding pockets inside proteins? How did nature "know" that the set of amino acids selected appears to be near ideal and optimal? How did Amino acid synthesis regulation emerge? Biosynthetic pathways are often highly regulated such that building blocks are synthesized only when supplies are low. How did the transition from prebiotic synthesis to cell synthesis of amino acids occur? A minimum of 112 enzymes is required to synthesize the 20 (+2) amino acids used in proteins. The Questions give us an idea what we are actually talking about here....