Scientists tell us that life on Earth began some 4 billion years ago, about half a billion years after the hypothetical great collision between planet Theia and Earth. The collision destroyed Theia and ripped the Earth apart, sending so much rock into orbit and forming the moon. If there was life before this time, scientists do not believe they would have survived such a great collision but then, we found stromatolite fossils some 3.48 billion years ago which could mean that life started around this time.
While Theia’s impact was the biggest, it was just one of the several impacts Earth had at the time as several large asteroids collided with Earth and their collisions were so massive that they melted part of Earth's crust and vaporized oceans. While we have agreed that life couldn’t have existed at the time of the collision, what could have birthed life on Earth?
Life as we see could have originated from chemical reactions that replicated molecules and sent information just like our genes do today. We could say that proteins, peptides, and RNA were early players in the formation of life formed from nucleobases like Thiamine, Adenine, Guanine, Cytosine, and Uracil, making RNA the first self-replicating molecule which was the precursor for life development on earth. When we talk about protein, Amino acids are the building blocks for peptides and protein and these are molecules that life depends on.
While these molecules were the precursors of life, the building block of life today comes from other life but the first life must have come from non-living things. Although scientists were guessing about how it could have happened, in 1952 there was the first clue when Stanley Miller went to recreate the early scenario of life form on earth since the idea that life started from the basic materials found on earth. He did this with Harold Urey who was a chemistry professor and a Nobel prize winner at the time.
They filled a large glass flask with half water and half gas with the gas being a mixture of methane, ammonia, and hydrogen. With this, they were able to create an ocean and atmosphere. He added two sparking electrodes just like the lightening at the time, and introduced heat to the water and gas. The following week, the mixture had turned from clear to reddish brown and this was analyzed the result was 5 amino acids discovered in large amounts which were used to build proteins. Today, scientists have recreated the Miller-Urey experiments with more advanced techniques and have seen over 40 amino acids in it. So lightening and materials on earth at the time were enough to create the building blocks of life.
This wasn't completely true as scientists found some issues with the experiment later looking at oxidizing gases. A 2023 study then included asteroids in the factor of the lab-simulated experiment. The collision showed that iron was distributed around the earth's surface and reacted with steam to form iron oxide. The hydrogen gas in the atmosphere reacts with nitrogen and carbon dioxide to form ammonia and methane. With this, we can see how amino acids are formed which are the building blocks of protein and life.
We could say that the asteroid collisions would have made the conditions for life and life didn't happen despite the collision rather life happened because of the collision. Although we do not know what caused the right condition for life, we know the building blocks for life came into existence, and life was formed.
Reference
https://www.technologyreview.com/2021/03/17/1021002/lightning-strikes-origin-life-astrobiology/
https://iopscience.iop.org/article/10.3847/PSJ/ab7e2c
https://www.nature.com/articles/s41467-021-21849-2
https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2021GL097504
https://iopscience.iop.org/article/10.3847/0067-0049/224/1/9
https://www.science.org/content/article/microbe-gives-clues-origin-life
https://www.nature.com/articles/s41467-023-36904-3
https://www.sciencedirect.com/science/article/pii/S0019103515001724?via%3Dihub
https://www.jstage.jst.go.jp/article/geochemj/48/1/48_2.0285/_article
https://www.nature.com/articles/s41467-022-29612-x
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4311869/
https://iopscience.iop.org/article/10.3847/PSJ/ac19b2
https://www.sciencedirect.com/science/article/pii/S0012821X15004926
https://www.nature.com/articles/srep38953
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2944365/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1063561/
https://www.semanticscholar.org/paper/New-insights-into-prebiotic-chemistry-from-Stanley-Bada/ee5b3b10e890dc36f2d67a206471924e78b4813e
https://link.springer.com/article/10.1007/s11084-007-9120-3