Multicellular life seems to have appeared independently from unicellular life several times in the past, including 6 instances of complex multicellular life from eukaryotic cells, that led to animals and land plants. It may also have happened repeatedly, with some disappearing altogether in course of time. Another important aspect of life is the extreme prevalance of symbiosis, even among unicellular life. It's even theorized that the genesis of the entire Eukaryota domain and many of its organnelles (notably mitochondria and chloroplasts) are the results of repeated cellular endosymbiosis where a unicellular organism consumed a prokaryote that eventually becomes a useful part of the host cell instead of its food.

Considering the two facts above and how often multicellular organisms and unicellular organisms interact, it's highly improbable that any multicellular organism would have evolved without developing a life sustaining dependence on a huge array of unicellular organisms. I would be very surprised if that happened.

I'm not dismissing your remark. Any day where you don't learn at least one new thing is a day wasted. But given the mathematical odds, what you said seems inevitable to me rather than a surprise.

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contingencies 4 days ago | parent | next [-]

It's even theorized that the genesis of the entire Eukaryota domain and many of its organnelles (notably mitochondria and chloroplasts) are the results of repeated cellular endosymbiosis where a unicellular organism consumed a prokaryote that eventually becomes a useful part of the host cell instead of its food.

A parallel could be drawn with CVCs acquiring startups. Or tiger penis soup. Neither being generally palatable dinner table conversation, but both similarly unlikely consumptive cultural concepts!

	▲	goku12 3 days ago \| parent [-]
		LOL! I don't know if I would compare symbiosis with predation or parasitism.

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accrual 4 days ago | parent | prev | next [-]

Thanks for the additional detail! It is really fascinating to think about not just the individual traits but the collective traits and behavior of life across Earth that got it where it is today. Indeed, I'm not surprised so much at finding life in all the cracks on earth (there is life even deep in the crust!) but moreso I didn't realize the scope of it (interior biomes, exterior biomes, etc). Really cool stuff. Makes me appreciate the trees even more.

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moi2388 4 days ago | parent | prev [-]

Do you have a source for this? I was under the impression that the scientific consensus today was that multicellular life only appeared once.

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andsoitis 4 days ago | parent | next [-]

> multicellular life only appeared once

Simple Multicellularity is estimated to have evolved at least 20 and probably more than 50 times for independent events of simple multicellularity.

Complex multicellurarity at least six times (animals, plants, fungi, brown and red algae).

https://en.wikipedia.org/wiki/Multicellular_organism

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mattmaroon 4 days ago | parent [-]

One has to imagine that there were a substantial number of misfires along the way too. Multi-cellular organisms that popped up and died for one reason or another before they had a chance to reach escape velocity. Like an amoeba that eats a bacteria and incorporates it but the mud puddle they are in dried up.

Wouldn’t surprise if for us to know about 50 at this point there were orders of magnitude more that we’ll never know of.

	▲	goku12 3 days ago \| parent [-]
		> One has to imagine that there were a substantial number of misfires along the way too. > Wouldn’t surprise if for us to know about 50 at this point there were orders of magnitude more that we’ll never know of. Indeed! The Wikipedia article mentions it. To be honest, it's a surprise that we know about 50 cases, given the fact that almost none of them had any hard tissue or structures (like bones or shells) that can survive as fossils. Given those odds, we are likely underestimating the cases by several orders of magnitude.

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goku12 4 days ago | parent | prev | next [-]

> I was under the impression that the scientific consensus today was that multicellular life only appeared once.

If that's the case, then the relevant Wikipedia article [1] will need a major correction. They reference multiple sources which are more likely to interest you.

Multiple independent emergence of multicellular life didn't really surprise me, considering how often unicellular life mutates. I'm actually surprised by the suggestion that the opposite is the current scientific consensus. Do you have any sources for that? (Not a challenge. Just want to understand the situation and misconceptions if any.)

[1] https://en.wikipedia.org/wiki/Multicellular_organism#Occurre...

	▲	moi2388 3 days ago \| parent [-]
		I was confused with Eukaryote cells

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griffzhowl 4 days ago | parent | prev | next [-]

You might be thinking of the genesis of eukaryotes, which is thought to be from a specific event where one archaeon incorporated a bacterium, and all eukaryotic organisms are descended from the resulting symbiotic arrangement, with our nuclear DNA descending from the archaeon, and our mitochondria descending from the bacterium.

All multicellular life is eukaryotic, but not all eukaryotes are multicellular, e.g. amoebae.

	▲	moi2388 2 days ago \| parent [-]
		Yes, you are right. This is exactly what I had it confused with, thanks!

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adrian_b 4 days ago | parent | prev [-]

Perhaps you think about animals, which have appeared only once, i.e. multicellular living beings capable of complex movements.

There are a lot of other kinds of multicellular living beings, which have achieved multicellularity independently, plants and fungi being the most obvious on dry land, but most of these other multicellular life forms had to lose mobility when becoming multicellular.

Only a few have retained some limited mobility when multicellular, e.g. the slime molds, but they are much simpler than those which have lost completely mobility, by having rigid cellular walls, like plants, fungi and several distinct kinds of marine algae.

There are even several kinds of (very simple) multicellular bacteria, among Cyanobacteria (blue-green algae), Myxobacteria (resembling slime molds) and Actinobacteria a.k.a. Actinomycetes (resembling fungi).