Originally, life evolved from non-living matter. Why is life only generated from other life nowadays, and why doesn't it evolve from inanimate matter, like it did originally billions of years ago, when life evolved on Earth?
Maybe I should reword this further. Living organisms reproduce other living organisms but the first living organism came from non living material or chemicals. So could life be created in a laboratory as it originally was ? Originally the process leading to a life form took one billion years, so would this be the answer to my question that it takes too long and that is why it is not being repeated again ?
Answer
Abiogenesis, the development of living things from non living matter, is not something we know much about, since it happened about 4 billion of years before we were around and haven't reproduced it in the lab. My guess is that it's not easy. However, the Miller-Urey experiment and others have told us something about abiogenic production of organic compounds.
The first living organism on Earth ( Let's imaging some self-replicating RNA ) was probably very inefficient, copied itself slowly and made a lot of errors. At the time it could survive because there wasn't any competition. However, as time went on some of these copies were more efficient and copied themselves more quickly, outnumbering the original sequences and driving them into extinction. Wait another 3.5 - 4 billion years and you have modern life.
If abiogenesis were to occur on Earth today, the resulting organism would likely be inefficient like the first organism. However, now it would face immense competition from very efficient modern organisms and would probably be eaten.
This is speculation, but I assume that any new type of life on Earth would be carbon based, since organic carbon based building blocks are abundant. If anything, abiogenesis might be easier on modern earth than early earth because the starting materials (nucleotides, amino acids) are readily available, but competition from modern life and reactive oxygen in the atmosphere would hinder any new abiogenesis.
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