Origin of life is important question. Scientists tried to answer it for many centuries: theological theories (gods created all on our earth and humans too), spontaneous generation (like rats appear from a bunch of food and clothes), Panspermia theory (life was brought in from space), static life (life always was, is and will be) and, finally, abiogenesis (life appeared thanks to chemical reactions and physical events on young Earth).
Last was suggested by scientists Oparin and Haldane. They suggested, that a lot of time ago in Earth’s oceans were enough organic, which after created coaservates and they evolved in protocells. But this theory of primordial soup has some disadvantages.
First is water. Big peptides and chains of nucleic acids aren’t stable in water. They decay into amino acids and nucleotides. Solving is little hygroscopic particles which will take all the water and bind it. It can be clay in mud.
Second. Not much time ago appeared synthetic biology - direction in science, which task is in creating biosystems having some properties, not meet in nature.
Benner, Steven worked on amino bases (or how does this part of nucleotide names?) And created two new nucleotides. They are complementary only to each other, can interact with peptides, working in cell with natural nucleotides and etc.
So, question. Why do we have only 4 nucleotides? We can watch at properties of them. First we can see even in formula - there is a first thing - sulfur. But in amino acids they are too. Then, maybe, physical properties? Natural nucleotides have a good protection against ultraviolet radiation, when synthetic not. And water, as you know, has a good protection against ultraviolet. So, if life wouldn’t appear in non-protected areas, we would have 6 nucleotides.
Third is chemical composition. Look at table of contents of ions in sea water, human’s blood plasma and cell’s cytoplasm.
Water and plasma have many similarities in composition, only Cu and Zn cations are different in more then 10². It’s easy to realise that the first multicellular organisms lived in seas and hadn’t organs to regulate composition of internal environments. After, when they appeared, organisms had adapted to this.
Similar story is with cells. But, if multicellular organisms could filter water, seeking needed molecules, ions, etc, then first protocells absolutely hadn’t. They had got all the substances thanks to water balance.
Let’s watch on example.
Phosphorus. Every cell has it: nucleotides and their derivatives (as ATP, GTP). Without this substance life is Impossible. But where phosphorus is in nature? Apatites and phosphorites. Them on Earth enough, but the main problem with it (why in seas not a lot of phosphorus) - they are poorly soluble and insoluble salts and chemically inert.
There are two ways to get it: meteorites, having a little phosphides (in two types of asteroids is Fe3P) and after reactions get soluble ions or volcanoes and associated with them Geothermal vents. Mud volcano is one of types of Geothermal vents. Apatites in warm decay into the different oxides, which exit the volcano in gases, but soon besieged near. Earth near to them is full of soluble forms of phosphorus.
And many many many advantages of theory of primordial pizza (it’s named so because water in them regularly evaporates, so stay only particles of clay with organic on them). Many important chemical reactions, some phenomena are possible only in mud volcanoes or near to them. If you are interested, i’ll write the most part. I have a good book, but i don’t know, is it on English and other languages.
And there is third theory - mayonnaise. It’s based on theory, that in ancient times were protomembranes - lipid bubbles. They would protect future RNA, peptides etc against different adverse effects. But it has a lot of critics, main problem is “eating” - nucleotides can’t go through those membranes. But it’s still alive because (4 8 15 16 23 42) it can explain how RNA developed.
There are some works, combining pizza and maionnaise, but pizza stays a leader.
Scientists are too hungry:D