As we all should know, abiogenesis and spontaneous generation are far from identical. For one, spontaneous generation was disproven with Pasteur, and abiogenesis seems to be a solid scientific theory. However, one can loosely summarize both as "the emergence of life from non-living materials" which, at the very least, is confusing for the layman.

My question is: What truly differentiates abiogenesis from spontaneous generation? For example, if abiogenesis were to happen again, how would we differentiate the two terms?

Is time the most contributing factor (abiogenesis happened over hundreds of millions of years)? Or the fact that abiogenesis generates "primitive organisms", while spontaneous generation assumes the generation of evolved, complex organisms?

  • 2
    $\begingroup$ I’m not sure why this question resurfaced after seven years, but is a good example of a bad question. It gets off to a bad start with “As we all should know”. This really antagonizes me. I don’t know, I feel there is no reason why I should know, and I resent being told I should by someone who doesn’t seem to know himself. If you talk about scientific terms on a science site you should define them, or if you don’t know the difference cite the definitions you have read that are causing you confusion. You are supposed to do some research yourself before posting here. $\endgroup$
    – David
    Commented Oct 11, 2020 at 21:15

3 Answers 3


One important difference is that spontaneous generation is a form of "mechanism" by which a certain species is "born", so it is repeated many times. For such complex organisms this would be part of their "life cycle". It would also need to be a regulated, robust process.

Abiogenesis, on the other hand, would create an organism which from that point on does not rely on abiogenesis in any way, so it would be a unique event. Abiogenesis is highly probabilistic which is why it would result in very simple organisms.


What truly differentiates abiogenesis from spontaneous generation?

There are three differences.

  1. Frequency

Abiogenesis occurs very infrequently. Perhaps only once in all of earth's 4.5 billion year history.

Spontaneous generation happens very frequently, in fact every new species could be a product of spontaneous generation. It occurs so frequently you just need to wait a week (given the Spontaneous generation example of fly generation from rotting meat)

  1. Complexity.

Abiogenesis only make very primitive organism... there are even thoughts that the abiogenesis event on Earth produced something that was only half alive, the ability to multiple and maintain a separate internal environment with a very basic and simple metabolism.

Spontanous generation on the other hand can produce both simple and complex organism. Bacteria, worms, cows, flies, humans. Anything.

  1. Reproducibility

Abiogenesis if it were done again... we might get very different biology. There are more than the 20 types of amino acid. There are actually a few more bases than the 4 we have in our DNA. And the codon usage... ie which 3bp of DNA encode for which amino acid could also be very different.

In spontanous generation events, you can get it to produce the same organism multiple times, right down to ability to mate with each other. Flies were the example.


The only reason abiogenesis is not disproved is because it can't be tested like evolution it is supposed to have happened in the past and won't happen again (at least not in the same way) abiogenesis is a theory proposed only because the origin of life is unexplainable by normal natural means.

Spontaneous generation was an earlier attempt at answering the origin of life that could more easily be proven or disproven.

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    $\begingroup$ Please add some references :) $\endgroup$
    – L.B.
    Commented Jan 2, 2017 at 19:49

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