# Multicellular evolution -- the 2BY gap

**URL:** <https://boards.straightdope.com/t/multicellular-evolution-the-2by-gap/189675>\
**Category:** Factual Questions\
**Created:** [July 20, 2003, 1:46am UTC](https://boards.straightdope.com/t/multicellular-evolution-the-2by-gap/189675 "2003-07-20T01:46:09Z")\
**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:** [September 8, 2015, 2:45pm UTC](https://boards.straightdope.com/t/multicellular-evolution-the-2by-gap/189675/22 "2015-09-08T14:45:17Z")

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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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