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Asked by anon-349315 on 6 Mar 2023. This question was also asked by anon-357525.
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Nikolai Adamski answered on 6 Mar 2023:
Scientists have found evidence that life existed on Earth 3.5 billion years ago. Early life forms were single celled organisms like bacteria for example.
It took ~2 billion years for the first multi-cellular organism to evolve. These first multi-cellular organisms evolved further, with different species coming into and going out of existence. We know of five mass-extinction events that have killed of vast numbers of species over the years. The survivors and their offspring eventually gave rise to all life we see on Earth today.If the wrong ancestor had died during one of these mass-extinction events, plants might not have evolved.
But the really tricky question is: How did life (those early single-cell organisms) appear in the first place? Because everything afterwards is just a consequence of this new life.
A major theory is that life on earth was seeded through comets and asteroids which brought the basic building blocks for life to evolve on Earth.
There is a nice summary of this on the NASA website. Check it out.
https://cneos.jpl.nasa.gov/about/life_on_earth.html
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Sam Mugford answered on 7 Mar 2023:
this is a tricky philosophical question, I think there’s a lot of ways to answer it. I like Nik’s answer. Another way to look at it is that plants have to exist, becuase if there were no plants we would not be able to exist. There would be no oxygen in the air, and no fresh water, and nothing for us to eat, so there would be no one to ask this question.
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Phil Howell answered on 10 Mar 2023:
Big question. They don’t have to exist – I’m pretty sure there are no plants on the moon – but we know that the only reason humans and other animals have enough oxygen to breathe is because of the magic tricks plant pull off in photosynthesis, when they use sunlight to power a process that turns carbon dioxide from the air and water into oxygen and sugars. We need the oxygen to breathe. We need the sugars and everything they turn into, to eat
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Alexandra Milliken answered on 15 Mar 2023:
Hmmm, this is a hard one. Nikolai Adamski has a very good response here.
But I can tell you the importance of plants existence. They provide us with the air we breath, the food we eat (whether directly from veg or indirectly from animals in the food chain), our furniture (chairs, tables etc), our fuel (bio-oil), our key medicines and they help to maintain our oceans (seagrass). Life would be pretty hard without them!
(Plus they are cool to look at 🌾 ) -
Martin Vickers answered on 16 Mar 2023:
I can’t add anything more to this, there are some amazing answers. If you want to try and answer this question, maybe start looking at pursuing a career in science 🙂
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