# Ontogeny recapitulates Phylogeny (Biology question) **URL:** \ **Category:** Factual Questions\ **Created:** [June 25, 2000, 10:33pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501 "2000-06-25T22:33:50Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Barney111](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@Barney111](https://boards.straightdope.com/u/Barney111)\ **Post date:** [June 25, 2000, 10:33pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/1 "2000-06-25T22:33:50Z")
When I was in college (20+ years ago), I had a bear of a biology professor who, while extremely tough, taught me alot. Anyway, I distinctly remember one lecture, in which he said," You may forget what this means, but I guarantee you will never forget this phrase." He proceeded to write “ontogeny recapitulates phylogeny” on the overhead. He was right. I’ve forgotten what it means.( I also don’t know why it suddenly popped back into my head, but that’s another thread). Can anybody tell me what the phrase means? ---
**Author:** ![Wood\_Thrush](https://avatars.discourse-cdn.com/v4/letter/w/b38774/32.png) [@Wood\_Thrush](https://boards.straightdope.com/u/Wood_Thrush)\ **Post date:** [June 25, 2000, 10:46pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/2 "2000-06-25T22:46:56Z")
The development of an embryo appears to repeat the evolutionary stages of its species. The entire phrase can be replaced with the verb “recapitulate” (sometimes normal words have special definitions in biology). ---
**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\ **Post date:** [June 25, 2000, 10:48pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/3 "2000-06-25T22:48:23Z")
I got it as ontogeny begats phylogeny. IIRC, it was the idea that the developing fetus sort of runs through its evolutionary stages while coming to full term. I don’t know if it is an accepted idea or not. ---
**Author:** ![olive](https://avatars.discourse-cdn.com/v4/letter/o/e9c0ed/32.png) [@olive](https://boards.straightdope.com/u/olive)\ **Post date:** [June 25, 2000, 10:49pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/4 "2000-06-25T22:49:07Z")
ontogeny recapitulates means "the development of the individual and phylogey means “the evolution of the species” so the phrase means the evolution of the species is in the development of the individual. ---
**Author:** ![Barney111](https://avatars.discourse-cdn.com/v4/letter/b/898d66/32.png) [@Barney111](https://boards.straightdope.com/u/Barney111)\ **Post date:** [June 25, 2000, 10:50pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/5 "2000-06-25T22:50:30Z")
Wood Thrush: Thanks. It’s all coming back to me. It always amazes me the things you can forget if you don’t use them. ---
**Author:** ![Wood\_Thrush](https://avatars.discourse-cdn.com/v4/letter/w/b38774/32.png) [@Wood\_Thrush](https://boards.straightdope.com/u/Wood_Thrush)\ **Post date:** [June 25, 2000, 11:03pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/6 "2000-06-25T23:03:02Z")
You would probably want rather to use the noun form, which is “recapitulation” or, alternately, “biogenesis.” ---
**Author:** ![Ringo](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Ringo](https://boards.straightdope.com/u/Ringo)\ **Post date:** [June 25, 2000, 11:10pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/7 "2000-06-25T23:10:09Z")
And I think, with “begats” I wrote it down in reverse; it should be phylogeny begats ontogeny. Which I might have caught had I remembered what ontogeny or phylogeny meant. Oh well. So, those who know, is it an accepted idea? ---
**Author:** ![Spiritus\_Mundi](https://avatars.discourse-cdn.com/v4/letter/s/c68b51/32.png) [@Spiritus\_Mundi](https://boards.straightdope.com/u/Spiritus_Mundi)\ **Post date:** [June 25, 2000, 11:13pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/8 "2000-06-25T23:13:58Z")
Right. The only problem, or so my cytogeneteist friend tells me, is that it really isn’t true. It makes a nice catch phrase, but as a “rule” it does not seem to accurately reflect what really happens during embryonic development. Damn. Next thing you know they’ll be telling you the Newtonian laws we learned in Physics I aren’t really true, either. ---
**Author:** ![manhattan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manhattan/32/7_2.png) [@manhattan](https://boards.straightdope.com/u/manhattan)\ **Post date:** [June 25, 2000, 11:55pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/9 "2000-06-25T23:55:04Z")
I’m certain that **Cecil** has addressed this question, but damned if I can find it in the archives. I’ll check the books tonight, but IIRC his conclusion is that it’s mostly bunk. I think that is over-generous, but I’ll expand on that when I find the column. ---
**Author:** ![divemaster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/divemaster/32/78_2.png) [@divemaster](https://boards.straightdope.com/u/divemaster)\ **Post date:** [June 26, 2000, 1:14am UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/10 "2000-06-26T01:14:02Z")
As the last couple of posters has indicated, the O-R-P theory has been discredited. The idea that mammalian embryos pass through the evolutionary stages is false. The idea was widely credited to Ernst Haeckel; unfortunately, it has been shown that his embryonic drawings were frauds–jimmied to fit with his preconceived notion. They can’t even really be considered honest mistakes on Haeckel’s part. Two quick examples: human embryos do not have “tails” that are comparable to that of other species. Sometimes a flap of tail-like skin is present (even at birth), but it is not supported by skeletal, vascular, or nervous systems, as with other species. Also, the claim that a human embryo has “gills” is false. Embryonic development includes “gill slits” which are better termed “pharyngeal pouches.” Unlike a fish gill (which is a vascularized structure used for gas exchange), a mammalian embryonic pouch is not. These pouches actually develop into specific anatomical features as the fetus develops. ---
**Author:** ![Arnold\_Winkelried](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@Arnold\_Winkelried](https://boards.straightdope.com/u/Arnold_Winkelried)\ **Post date:** [June 26, 2000, 2:32pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/11 "2000-06-26T14:32:19Z")
Cecil Adams did shortly discuss the phrase on pages 476-477 of his book “[_More of the Straight Dope_](http://www.straightdope.com/otheroutlets/books.html)”. It wasn’t really a Straight Dope column. In that book they have short “quizzes” interspersed between the articles, and this is an answer to one of the quizzes. His verdict: > [@](#): > > While as a fetus you do bear a resemblance to some of your long-departed ancestors at certain points, you skip a lot of intermediate steps. Also, you pick up a lot of uniquely human characteristics pretty early on. So while “ontogeny recapitulates phylogeny” is true in a loose sense, at best it’s an exaggerations of what’s really happening. ---
**Author:** ![SuaSponte](https://avatars.discourse-cdn.com/v4/letter/s/67e7ee/32.png) [@SuaSponte](https://boards.straightdope.com/u/SuaSponte)\ **Post date:** [June 26, 2000, 3:37pm UTC](https://boards.straightdope.com/t/ontogeny-recapitulates-phylogeny-biology-question/23501/12 "2000-06-26T15:37:04Z")
From The Mote in God’s Eye by Niven and Pournelle, p. 127. Discussion of an alien subspecies: “‘Ontogeny recapitulates phylogeny’ someone said. Someone else said, ‘Oh, shut up’” So, over a thousand years in the future, biologists will still be debating this point. Unless Unca Cece settles it between now and then. V.