# How did sex evolve? **URL:** \ **Category:** Factual Questions\ **Created:** [June 12, 2012, 2:42am UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871 "2012-06-12T02:42:06Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [June 12, 2012, 2:42am UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871/1 "2012-06-12T02:42:06Z")
At first, there were little creatures dividing in half to make copies of themselves. Now, we have big creatures mixing their genes with each other to make new creatures. Something had to have happened in the middle. How did we get here from there? ---
**Author:** ![Wendell\_Wagner](https://avatars.discourse-cdn.com/v4/letter/w/8491ac/32.png) [@Wendell\_Wagner](https://boards.straightdope.com/u/Wendell_Wagner)\ **Post date:** [June 12, 2012, 3:03am UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871/2 "2012-06-12T03:03:54Z")
For whatever it’s worth, here’s the Wikipedia entry on this subject: > **[Evolution of sexual reproduction](https://en.wikipedia.org/wiki/Evolution_of_sexual_reproduction)** > > Sexual reproduction is an adaptive feature which is common to almost all multicellular organisms and various unicellular organisms, with some organisms being incapable of asexual reproduction. Currently the adaptive advantage of sexual reproduction is widely regarded as a major unsolved problem in biology. As discussed below, one prominent theory is that sex evolved as an efficient mechanism for producing variation, and this had the advantage of enabling organisms to adapt to changing environ... ---
**Author:** ![J\_Cubed](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@J\_Cubed](https://boards.straightdope.com/u/J_Cubed)\ **Post date:** [June 12, 2012, 3:08am UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871/3 "2012-06-12T03:08:38Z")
Dinner and a movie? > [@Wendell\_Wagner](#): > > For whatever it’s worth, here’s the Wikipedia entry on this subject: > > [Evolution of sexual reproduction - Wikipedia](http://en.wikipedia.org/wiki/Evolution_of_sexual_reproduction) Specifically, it sounds like you want the “Mechanistic origin of sexual reproduction” section. ---
**Author:** ![outlierrn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/outlierrn/32/3005_2.png) [@outlierrn](https://boards.straightdope.com/u/outlierrn)\ **Post date:** [June 12, 2012, 5:29am UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871/4 "2012-06-12T05:29:48Z")
I’m a Red Queen fan, myself. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [June 12, 2012, 3:03pm UTC](https://boards.straightdope.com/t/how-did-sex-evolve/624871/5 "2012-06-12T15:03:54Z")
There is a somewhat obvious path for the original development (which may not be the correct one): -similar organisms learn to exchange genetic material for occasional advantage. -this eventually becomes a common and frequent behaviour. -at one point, one organism learns to cheat, to create a spare half-gene set (haploid) for exchange without accepting the other organism’s genes in return. It gets the best of both worlds - create copies of its genes, but not accept potentially flawed genes. -when two such cheaters meet, they produce 3 sets of genes in 2 cells - the next logical step is that one cell ends up with 2 sets of genes and so it has to split. -Now, the one that cheats even more, and most "isolates"or pinches it original self off from the merge process does not get stuck with the second set of genetic material, and so wins - it gets “offspring” containing a copy of some of its genes without having to accept possibly defective genes in return and without having to split afterward, losing half of its cell volume. -if two such cells “meet” and hug each other in a special way, both are possibly pushing out/ pinching off, an almost complete haploid cell to fuse with the same thing from the other organism. -eventually, two cells that meet will each contribute an almost separated haploid cell that will fuse with the other’s, to create a third hybrid organism. Then, it gets to the point of the haploids separate from the “parent” before fusing with each other. It’s win-win; the organisms with useful mutations do not have to accept possibly defective genes; the same organism can keep spewing out haploid cells with the useful mutation over and over (which makes offspring that then can also reproduce). This can speed up the proportion of the population with a beneficial mutation, and also the likelihood of it forming complementary beneficial mutation hybrids. The creation of a presumably smaller haploid cell requires less biological material, so less cost, than creating enough material for a split into two complete cells.