# Talk:Homology (biology)

The Sequence homology section is becoming as long and richly structured as the rest of the article put together, so I propose we split it out as a new article in its own right (currently, Sequence homology redirects here), leaving behind a "main" link and a short summary. It isn't badly cited but there are paragraphs lacking links that would benefit from such. Chiswick Chap (talk) 07:38, 3 October 2016 (UTC)

Ok, I've boldly gone and split the article out, leaving a linked summary in the article body, and a paragraph in the lead. There's much to tweak at both ends of the link. Chiswick Chap (talk) 13:21, 5 October 2016 (UTC)
Good work Chiswick Chap. A paper worth referencing in the sequence homology section here: Inkpen,S.A. and Doolittle,W.F. (2016) Molecular Phylogenetics and the Perennial Problem of Homology. J. Mol. Evol., 1–9. T.Shafee(Evo&Evo)talk 05:35, 28 November 2016 (UTC)
Thanks! By the logic of the split, we'd write about it in the other article, and then (if it was a big enough point) briefly mention it here also. Chiswick Chap (talk) 07:10, 28 November 2016 (UTC)

The criticism section is VERY poorly referenced, original research and should be removed, User:WilliamJamesHerath who has a conflict of interest is edit warring to include it against consensus. Theroadislong (talk)

A better way of describing it is "embarassingly bad" and "indicating a total lack of knowledge of anything that's happened in the past 40 years of evolutionary developmental biology".  The paragraph of confirmation bias is literally nothing but a baseless assertion with zero evidence, the second paragraph suggests that he doesn't even understand the definition on homology as he clearly confuses it with homoplasy (which is literally the exact opposite phenomenon), and his characterization of DeBeer's work is ignorant of literally the past 40 years of evo-devo which perfectly address these questions.   User:WilliamJamesHerath is clearly ignorant of such fundamental concepts as Hox genes, segmental homology, ectopic expression, gene duplication, signalling proteins, Turing patterns, and immunohistochemistry. User:WilliamJamesHerath, if you genuinely want to learn about this topic, read "From DNA to Diversity" and "Endless Forms Most Beautiful", both by Sean Carroll.  But right now your level of knowledge and reasoning is painfully, embarrassingly ignorant of so much science that it's like listening to a flat-earth believer. HCA (talk) 23:43, 25 February 2017 (UTC)
I'm glad it's been removed as it was point-of-view pushing "original research"—utterly lacking in either originality or knowledge of research, but that's by the by. The section added nothing to the article and did not belong in it. If its author had taken the trouble to look up what is known of the subject, he would have discovered some of the evidence described in the rest of the article. Chiswick Chap (talk) 09:46, 26 February 2017 (UTC)

This review is transcluded from Talk:Homology (biology)/GA1. The edit link for this section can be used to add comments to the review.
Reviewer: Aircorn (talk · contribs) 22:40, 3 May 2017 (UTC)

Thanks for taking this on. Chiswick Chap (talk) 07:27, 4 May 2017 (UTC)
No problem. Will get some comments up in the next few days all going well. AIRcorn (talk) 07:57, 4 May 2017 (UTC)
As usual I am willing to discuss any comments that I make and am happy to be convinced that the article is fine without addressing the comment.


### Review
GA review – see WP:WIAGA for criteria

I have read the article and it is excellent. I feel it probably meets the GA criteria as is. However I have a few questions and comments. With articles like these I try to make sure they are accessible to the lay person and this mostly accomplishes that.
Many thanks.
Is it well written?
A. The prose is clear and concise, and the spelling and grammar are correct: 

B. It complies with the manual of style guidelines for lead sections, layout, words to watch, fiction, and list incorporation: 

Is it verifiable with no original research?
A. It contains a list of all references (sources of information), presented in accordance with the layout style guideline: 

B. All in-line citations are from reliable sources, including those for direct quotations, statistics, published opinion, counter-intuitive or controversial statements that are challenged or likely to be challenged, and contentious material relating to living persons—science-based articles should follow the scientific citation guidelines: 
Will check some sources soon
C. It contains no original research: 
There could be an argument that the use of examples may be considered original research, but they are a necessary part of the article and I fall on the other side of those arguments usually
D. It contains no copyright violations nor plagiarism: 

Is it broad in its coverage?
A. It addresses the main aspects of the topic: 
Was going to pass this even without the history section, but now that just adds to it. Would consider moving the definition ahead of it as it can be good to know what you are learning the history of, but this is not necessary.
B. It stays focused on the topic without going into unnecessary detail (see summary style): 

Is it neutral?
It represents viewpoints fairly and without editorial bias, giving due weight to each: 

Is it stable?
It does not change significantly from day to day because of an ongoing edit war or content dispute: 
Lot of major editing since this review started.
Not really, just added a paragraph on the history. Nothing else changed. Chiswick Chap (talk) 08:22, 7 May 2017 (UTC)
Okay, will read that section later. For a moment there I thought I had clicked on the wrong article.
Is it illustrated, if possible, by images?
A. Images are tagged with their copyright status, and valid fair use rationales are provided for non-free content: 
Will check later
B. Images are relevant to the topic, and have suitable captions: 

Overall:
Pass or Fail: 
Whoa there. A whole new section just appeared, plus a lot of other changes.[1] I am not sure how relevant the below comments are now as they are based on an old revision. Can you let me know when it is ready for a review.
Sorry, and I've finished, I just realised yesterday that there really should be a brief mention of the history. Chiswick Chap (talk) 08:22, 7 May 2017 (UTC)
If you mainly just added a history section then the below may still be relevant. I want to work on some of my own stuff for a bit, but you are welcome to address any comments below. I will check some sources and read through the history section later. The article was good so no need to feel you have to make any changes I suggest. I imagine you know more about this stuff than me anyway. AIRcorn (talk) 08:44, 7 May 2017 (UTC)
No problem, I'm working to address them now. Chiswick Chap (talk) 08:46, 7 May 2017 (UTC)


### Comments
Homology is the relationship between biological structures or sequences that are derived from a common ancestor This is accurate and sufficient, but I wonder if it could this be explained a little better as a starting definition for the average audience. Relationship seems to be a rather vague descriptor. I like the lead description better.
Mm, yes, it was correct, but I've reworded it to mention taxa, as in the lead.
There is no mention of evolution (divergent or otherwise) in the definition until the examples. It is mentioned prominently in the lead and would probably help the early definition if it is specifically linked and called upon.
Good idea, done.
Should there be a comparison between homology and homoeology?
I don't think so.
Would Most recent common ancestor be a better wikilink than Phylogenetic tree
Used tree of life instead.
Is there a better way to present examples of Analogy than starting each sentence "For example". Table perhaps? or maybe just a rewording to make it a bit less repetitive. Particularly the last two as the two examples are closely related.
Reworded.
Primary homology is that initially conjectured by a researcher based on similar structure or anatomical connections, who states a hypothesis that two characters share an ancestry. Found this a little confusing in its wording. Would saying "primary homology is the initial hypothesis made by a researcher based on similar structure or anatomical connections" be simpler? Conjectured and hypothesis are pretty similar (especially to a lay person).
Done.
although some may be highly counter-intuitive I am assuming this is referenced in "Brusca, R.C. & Brusca, G.J. 1990. Invertebrates. Sinauer Associates, Sunderland: P. 669". We have a lot of different examples, but is there one for it being counter-intuitive or at least an explanation on why it is? Is this a general statement or is this specific to arthropods.
Yes, it's quite general. I've moved it up and added an example.
I thought there might be more examples in mammals. Maybe a mention of vestigial structures (tail bone)?
Actually I feel that with human, dog, and whale pictured right up front, along with bat and horse in the lead paragraph, we are already emphasising mammals rather heavily.
Maybe could use some cool examples/pictures of leaf homology in plants (venus fly trap, pitcher plants etc).
Good idea... added images of some very different leaves, and mention of these in text. Chiswick Chap (talk) 13:02, 7 May 2017 (UTC)
when a species diverges into two separate species, the copies of a single gene in the two resulting species are said to be orthologous. Orthologs, or orthologous genes, are genes in different species that originated by vertical descent from a single gene of the last common ancestor. Isn't this saying the same thing?
Pretty much; removed.
Not sure you need an easter egg link in behaviour as well as a main templated link.
Removed.
Is there more to behaviour. A whole section devoted to a single paragraph seems a bit underwhelming. I don't know much about this aspect so wont be much help. If there is not much more to this maybe it would be better mentioned under definition.
Well, although new and controversial it represents a different aspect, i.e. we have body parts, embryonic development, gene sequences, and behaviour as places where homology is studied. Also, given its status, it wouldn't be right to treat it as part of the definition. I have added an example of primate behaviour to the section, which while controversial is at least well cited and supported by evidence.


#### Non-reviewer comments
Homology is a huge topic; probably tens of thousands of books and articles have been written about it. I'm very skeptical that by citing less than 30 of them, and each only once or twice, this articles comes close to broadness coverage (even when taking into account that the threshold is significantly lower than the "comprehensiveness" of coverage in FA). Take the "In plants" section for example. It tries to summarize all major aspects of homology in plants in just two sentences. With a readable prose size of 10 kB, this article is just a tenth of the practical maximum size of a Wikipedia article, and sixth of the example article for B class. It's not like there is a shortage of literature on this topic (a situation that somtimes prompts the "is this too short for GA?" type of discussions on WT:GA), but for some reason it is simply not cited and summarized here. – Finnusertop (talk ⋅ contribs) 18:08, 7 May 2017 (UTC)
1) Breadth means we cover 'the main points', which the article does. 2) I'm very happy to add some more on plants (I'll do that now) or other aspects of the subject, but I do not believe this will change the tenor of the article in a significant way. 3) The taxa chosen (arthropods, mammals, plants) were selected because they are familiar, with readily-understood examples, and together they make an important point, which is that homologies can be found in quite different taxa, always on the same principle. Examples could be repeated a hundredfold from other taxa, but with rapidly diminishing returns – the article would become longer, but steadily less readable, and would convey very little more understanding. 4) It is not our job to attempt to cite all the literature ever written on any topic, but to summarize and explain what the topic is for a general readership, cited to reliable sources. For comparison, Evolution (of which this is a subtopic) is covered in some 300 citations: a vanishingly small percentage of the libraries full of books, papers, pamphlets, popular articles and cartoons on that genuinely "huge" subject. So, let's not over-egg this pudding. If there's anything definite people want to add, it'll be done promptly. Chiswick Chap (talk) 18:43, 7 May 2017 (UTC)
@Chiswick Chap: Thank you for the reply. With regards to "main points", I'm a bit disppointed by how vaguely the GA criteria cover this aspect. Is adding a dozen empty or near-empty sections "covering" these aspects (and I don't accuse this article of doing something like that), or do these points need to be covered at a given length?
The coverage criterion is supposed to be analogous to what I have already cited above as part of the B class criteria. More so, it is supposed to surpass the requirements of B class. In fact, of even B class it is said that it "contains a large proportion of the material necessary for an A-Class article", which in turn is a "complete description of the topic ... It should be of a length suitable for the subject". This, to me at least, implies that a GA is supposed to be very near completion. True, it is diffucult to give a tangible target for article length, but when an article strikes me as ambitious in scope but short in length (with not too many citations) then I think it's indicative of a possible problem that deserves a heads-up for the reviewer. With everything else that you say, I completely agree. – Finnusertop (talk ⋅ contribs) 21:44, 7 May 2017 (UTC)
Many thanks. I have extended the coverage on plants as requested. Chiswick Chap (talk) 06:12, 8 May 2017 (UTC)


### History section
Pretty large paragraph, but reads well.
Wasn't sure on the reliability of the Embryo project, but it has an editorial team[2] and Jane Maienschein seems qualified enough so not too worried.


### Source check
Homology history of a concept[3]
reliable, can't access but AGF that it is used correctly
Homology: From jaws to ears — an unusual example of a homology"[4]
Supports text, not plagerised and reliable
Homology: Leave It To the Plants[5]
Supports text, not plagerised and reliable
Homology, Genes, and Evolutionary Innovation[6]
Well explained from text
Secret Found to Flight of 'Helicopter Seeds'[7]
Given the broad interpretation of analogy I feel the use of this example is alright. In particular Thus, the new study, detailed in the June 12 issue of the journal Science, shows that plants and animals have converged on an identical aerodynamic solution for improving their flight performance.. Would we not be better served citing the original study though instead of some pop science website?


### Final comment
I am satisfied that in its current state (even following the recently added comments and taking into account the concerns of Finnusertop) that this meets the GA criteria and is worthy of being labelled a good article. Passing. AIRcorn (talk) 09:03, 17 May 2017 (UTC)

Many thanks. I'll add the 2016 Science paper. Chiswick Chap (talk) 09:23, 17 May 2017 (UTC)

Can you create section name 'Homologous organs', so it will be easy to find someone. AlistairMcMilan (talk) 16:24, 1 November 2020 (UTC)

Hello,
I have been working with paleontologists recently and was informed the illustration titled "The Cretaceous snake Pachyrhachis problematicus had hind legs (circled)." on this page actually depicts a Eupodophis. I made the change on Wikimedia Commons but am now trying to alert users of the image on Wikipedia so they may correct the mistake. FYI (to help rename without losing content) both Eupodophys and Pachyrhachis had hind legs, the main differences lie in the shape of the head.--Flor WMCH (talk) 14:31, 17 June 2022 (UTC)