I have heard it argued that life as we know it (DNA-, RNA- and protein-based) could not have evolved without the ozone layer to protect it from UV radiations.

It seems to me that mechanisms to deal with this would have evolved. Is there any scientific evidence on this point?

  • 5
    $\begingroup$ Life on earth predates the ozone layer by over a billion years. $\endgroup$
    – canadianer
    Jul 27, 2022 at 2:13
  • $\begingroup$ Welcome to Biology.SE. This is not simply an answer site, but instead a site that promotes self-learning with some expert help. Consequently, questions that show little or no prior research effort are off-topic on this site. Please edit your question and tell us where you've looked for answers, what you do know about the topic, and where exactly you still have questions. I suggest starting with a search like "UV protection plant" — you will find a lot of information showing that this has happened (obviating you post). Please see the tour and help center starting with How to Ask for details. $\endgroup$
    – tyersome
    Jul 27, 2022 at 3:53
  • 3
    $\begingroup$ Donno, maybe intelligent design shouldn't play with UV to start with. Or leap seconds. $\endgroup$
    – X Zhang
    Jul 27, 2022 at 5:46
  • $\begingroup$ If you're interested in hypothetical questions, perhaps relating to a fictional world you are thinking about creating, then Worldbuilding is a splendid resource for that. $\endgroup$ Jul 27, 2022 at 8:27

1 Answer 1



The original question asked about fair assumptions, but addressed conviction rather than scientific evidence. This site primarily exists to address biological questions that can be answered or at least approached objectively. It certainly does not exit to rehearse people for arguments against those who have already made up their minds on a topic because of religious convictions. So I changed the question to restrict it to UV-resistance of living organisms.


It is already known that organisms currently exist that are resistant to ultraviolet radiation. The bacterium, Deinococcus radiodurans, an extremophile which is also resistant to other radiation, is a prime example.

In addition, organisms, including higher organisms, have mechanisms for repairing DNA damaged by ultraviolet light, as summarized in this brief Nature Scitable article.

Hence, even without knowing that the ozone layer postdated the origin of life by a billion years (as @canadianer pointed out), there is ample evidence that life would have managed to deal with ultraviolet light.


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