How did the first ever living creatures start, how can life start from nothing?
In: Biology
We don’t know the specifics. We do know that amino acids can be produced in environments similar to a primordial Earth, so it’s possible that an incredibly simple self-replicating piece of RNA just happened to form, which then could spread and evolve into life as we know it, but that’s only a hypothesis that has not been experimentally confirmed.
Sometimes, amino acids randomly happen to configure themselves into a stable state that just so happens to have the right configuration to catalyze the reaction of other amino acids into the same arrangement.
In other words: Given the right circumstances, this arrangement of amino acids happens to create copies of itself. Sometimes, those copies are not perfect, but instead, produce slightly different arrangements. This is a process known as “mutation”.
If something mutates, it might happen to turn into an arrangement that is even better at creating copies of itself than the original one. This is known as “evolution”.
The best arrangements at creating copies of themselves will end up becoming more numerous, thus creating even more copies of itself than alternate arrangements do. Eventually, the majority of arrangements will be those that are the best at creating copies. This is known as “natural selection”.
After the ocean ran out of amino acids, these arrangements could no longer spread as easily. Until some arrangements happened to randomly contain the right type of chemical bond causing them to break apart *other* arrangements of amino acids back into their constituent amino acids. In response to which, arrangements started flourishing in which the vulnerable amino acids ended up surrounded by more resistant molecules.
The arms race is still continuing today. At some point we just stopped calling them “arrangement of amino acids” and started calling them “lifeforms”.
A single cell randomly split in two and made more of itself. To this day we carry on its legacy to replicate and create more of us. Us as in all living life right now, trees, dogs, worms, fish. The meaning of all life is to replicate and create more like us.
Well, right off the bat, you need to realize that ‘life’ is a complex chemical reaction.
If you start examining smaller lifeforms, the smaller you get, the more simplistic you get until you get to the point where you see viruses and people aren’t even sure if those things technically qualify as ‘life.’
I guess what I’m saying is that chemical reactions are fairly common and happen from the interaction of different elements and chemical compounds and life arises from that.
How did life arise from chemical reactions on Earth? Chances are, it didn’t and microscopic life drifted down to Earth from space from some other source.
No one knows for sure, really.
The first life started as just an RNA molecule. It wasn’t a cell, it had no metabolism. It relied on its environment to provide whatever chemicals were necessary to aid in the 1 & only thing it could do… replicate itself. Through mutations, some RNA molecules attracted stabilizer chemicals close to them, chemicals that would prevent the RNA from breaking up. EONs later the evolution of the stabilizer chemicals arent just attracted to, but created by the RNA & it eventually becomes the cell guts & cell wall.
No one knows for sure, but we have some ideas of how it might have happened.
Someone mentioned underwater vents, which is a common theory for how life may have formed on earth at first. I will elaborate a little in an ELI5 way.
Life is a bunch of complicated chemical reactions. Water is needed for many of these reactions. So, we think life started underwater. Life also needs things called “organic compounds” which are basically just some common ingredients like oxygen that we tend to find in almost all life. We also think that there must have been a LOT of chemical reactions happening before one happened that got it just right to create life. Many of these reactions need some source of heat. This brings us to underwater vents.
These vents are basically places where super hot stuff from inside of the earth vents out into the ocean. This means that a lot of compounds, including organic compounds, are thrown into the ocean, which is water. The vents have a lot of heat, and there is less heat as you get farther from the vent. So, whatever heat level might be needed for a chemical reaction to start life should be somewhere nearby the vents, as well as all the other needed ingredients.
However, this just means that life theoretically MIGHT have started at one of these vents, because we can’t think of anything missing from the equation there. But, we don’t know the whole equation and we don’t know that there may have been somewhere else that life really started.
This is an interesting book if you want to look at some of the physical and chemical constraints.
https://www.google.com/books/edition/The_Vital_Question_Energy_Evolution_and/hwudBAAAQBAJ?hl=en&gbpv=1&printsec=frontcover
We don’t know for sure, but the most likely explanation at the moment seems to be that some relatively simple self-replicating molecule was formed in a deep-sea alkaline hydrothermal vent. It only had to happen once, then this molecule could replicate, with copying mistakes providing the driver for evolution by natural selection to take over from there until, eventually, the first cells arose.
Then God said: Let the water teem with an abundance of living creatures, and on the earth let birds fly beneath the dome of the sky. God created the great sea monsters and all kinds of crawling living creatures with which the water teems, and all kinds of winged birds. God saw that it was good, and God blessed them, saying: Be fertile, multiply, and fill the water of the seas; and let the birds multiply on the earth.
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