# Why did life take so long to become multicellular?

**URL:** <https://boards.straightdope.com/t/why-did-life-take-so-long-to-become-multicellular/808353>\
**Category:** Factual Questions\
**Created:** [February 7, 2018, 6:39am UTC](https://boards.straightdope.com/t/why-did-life-take-so-long-to-become-multicellular/808353 "2018-02-07T06:39:42Z")\
**Posts on this page:** 1\
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**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\
**Post date:** [February 7, 2018, 9:38am UTC](https://boards.straightdope.com/t/why-did-life-take-so-long-to-become-multicellular/808353/3 "2018-02-07T09:38:04Z")

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This question [was asked 14½ years ago in a thread titled “Multicellular evolution – the 2BY gap.”](http://boards.straightdope.com/sdmb/showthread.php?p=18668792)

The conclusion was that _ **oxygen, manufactured by one-celled creatures, was a prerequisite for higher life,** _ and it took a long while to get sufficient oxygen. Dopers seemed satisfied … but 12 years later someone bumped that thread to ask if there were any other ideas. Being a narcissist, I’ll repeat my answer to the bump:

> [@Multicellular evolution -- the 2BY gap](https://boards.straightdope.com/t/multicellular-evolution-the-2by-gap/189675/22):
>
> One way to guess which parts of evolution were difficult is to consider _how often they occurred on Earth._
> 
> - Engulfing of organelles to create new kingdoms of eukaryotes? This seems to have happened multiple times.
> - Multicellular organisms? My understanding is that multicellular plants, animals, seaweeds, and fungus _were all independent developments_. (I think I’m missing some kingdoms from that list.)
> - The initial creation of replicating chains? There may have been AEG chains even before RNA. [AEG chains are still found in some cyanobacteria.](http://www.astrobio.net/topic/origins/origin-and-evolution-of-life/did-aeg-come-before-dna/)
> - Ocean life becoming land life? Multiple occurrences.
> 
> This is why I think the “invention” of sex was a very key development. It seems to have happened just once. I think it may have been prerequisite to rapid evolution.

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