Talk:History of life/GA1

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GA Review[edit]

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GA review – see WP:WIAGA for criteria Nicely written article on an interesting topic. It is quite long, leaving little room for expansion. This may be borderline allowed under Wikipedia:LENGTH#Occasional exceptions, so I won't hold up GA status over that. But a future split may be appropriate. (A possibility is splitting off the multi-cellular evolution section, as that occupies about half the content.)

  1. Is it reasonably well written?
    A. Prose quality:
    B. MoS compliance:
    The formats of some of the citations are inconsistent. Levy and Miller (1998), and Larralde et al (1995) use semi-colon separated author lists, while others use commas. Trevors and Abel (2004) has a mixed name format. Crick and Orgel (1973) has a comma after the date. Günter Wächtershäuser lists first and last, as does Christopher B. Field et al.; others do the reverse. Grazhdankin (2004) doesn't list the first name. MacLeod et al (1997) doesn't punctuate initials. Please make the citations use a consistent style.
  2. Is it factually accurate and verifiable?
    A. References to sources:
    B. Citation of reliable sources where necessary:
    C. No original research:
  3. Is it broad in its coverage?
    A. Major aspects:
    I listed some concerns in the attached below. These have been resolved.
    B. Focused:
  4. Is it neutral?
    Fair representation without bias:
  5. Is it stable?
    No edit wars, etc:
  6. Does it contain images to illustrate the topic?
    A. Images are copyright tagged, and non-free images have fair use rationales:
    B. Images are provided where possible and appropriate, with suitable captions:
  7. Overall:
    Pass or Fail:
    On hold pending resolution of issues. Thanks.—RJH (talk) 19:28, 11 January 2009 (UTC)[reply]

Fixed all the ref format issues I could see. Except that Cavosie et al (2005) still ends "and E.I.M.F." becuase that's what the target of the doi link says. The only citation of this that I could find omits "and E.I.M.F." - but adds it in an another cite of the same authors published 2007. --Philcha (talk) 09:12, 13 January 2009 (UTC)[reply]

The page looks good. Thank you for addressing my concerns. I'm going to promote it to GA.—RJH (talk) 17:52, 13 January 2009 (UTC)[reply]

Hi, RJH, thanks for your help, it's been a fun review. Thanks also to Tim Vickers for helping to smooth off some of the rough edges. --Philcha (talk) 18:28, 13 January 2009 (UTC)[reply]

Resolution of issues

First I'd like to say that I'm not an expert in this area, although I do have a stong interest in scientific topics. I'm coming at this as a lay person and seeing if it would answer some fairly basic needs, as well as checking compliance with the wikipedia guidelines. Hopefully this is acceptible. I started off checking the GA criteria but this ended up more like a PR. Here are some of the concerns I have:

  • The lead does not comply with WP:LEAD. For example, it has an excessive number of paragraphs. (The rule of thumb is four for large articles.) Also, the first paragraph of the lead should be a succinct description of the topic. For example, "The evolutionary history of life explains the current biological diversity of the planet Earth. Each life form acquires a series of inherited traits from its ancestors, and these traits are selected by survival and reproduction. This process stretches back at least 3,000 million years, ..." or some such.
  • The final sentence of "The clay theory" section seems to dangle. Perhaps it can be merged at the end of the first paragraph?
  • In the first paragraph on Stromatolites, how does finding a second 3.5 Gyr old Stromatolites negate the criticism? This is unclear to me.
  • Some basic questions seem to be unanswered: What is the role of water in the appearance of life? Why did life evolve to use carbon-based proteins and not something based on sulfur, for example? Don't these seem appropriate topics for an article on evolutionary history?
  • The microbial mats section doesn't explain why these evolved. Did bacteria evolve as independent organisms first or in mats? Something you might consider for this section is File:Oxygenation-atm.svg, along with an appropriate caption.
  • Why nothing about the reasons for the evolution of photosynthesis? Why are photosynthetic organisms green and not black? What about the evolution of predators?
  • Upon reading the multicellularity section, it immediately becomes unclear (to me) why microbial mats are not considered multicellular organisms. Are bacteria composed of two or more unrelated species? Perhaps this can be clarified in the text?
  • The following sentence seems like self-editorializing: For the sake of brevity this article focusses [sic] on the... "rather anthropocentric". I think it would be better as a note.
  • The "Horodyskia" image should be moved down to the next section. Also, the relevance of the caption to the section is unclear.
  • The "Plants and the Late Devonian wood crisis" section could explain some other features of plants, such as leaves, vertical growth and bark.
  • In the Land invertebrates section, could the article mention when and why insects developed flight? Is this related to the emergence of flowering plants?
  • Do former land animals that evolved for life at sea deserve mention?
  • Shouldn't there be more discussion of ecosystems as drivers of evolutionary history? I see flowering plants and parasitism (as related to sexuality), but it seems like some general discussion might be worthwhile. For example, the formation of soil for land plants, and the evolution of plants as drivers of animal species (apes, insects, &c.).
  • The caption for File:Opabinia BW.jpg needs a citation. Also, the images File:Acanthodes BW.jpg and File:Acanthostega BW.jpg should be cited if you're taking this for FA. File:Phanerozoic biodiversity blank 01.png has a tag indicating lack of authorship information.

Hi, RJH, I've copied your comments in order to respond:

  • The lead does not comply with WP:LEAD. For example, it has an excessive number of paragraphs. (The rule of thumb is four for large articles.) Also, the first paragraph of the lead should be a succinct description of the topic.
    • Re number of paras, each describes a separate stage - very briefly. As a result any combining of paras would be arbitrary, e.g. the 3rd would fit as well (or poorly) with the 2nd or the 4th. A similar question arose in the GA review of Arthropod, the reviewer asked for a 2nd opinion, and the conclusion was WP:IAR. --Philcha (talk) 11:29, 10 January 2009 (UTC)[reply]
    • Re the 1st sentence, yes it should explain the title. I've edited it, let me know what you think. --Philcha (talk) 11:29, 10 January 2009 (UTC)[reply]
      • That works, thanks.—RJH (talk) 17:49, 11 January 2009 (UTC)[reply]
        • I've cut the lead down a bit more. Tim Vickers (talk) 23:55, 11 January 2009 (UTC)[reply]
          • The helpful revision to the lead has been removed, so I'm uncommenting my concern and considering this unresolved.—RJH (talk) 17:27, 12 January 2009 (UTC)[reply]
            • Oh, sorry. I didn't see that comment and it seemed a bit redundant to me when I was condensing the text. No objections to it being added back. Tim Vickers (talk) 17:36, 12 January 2009 (UTC)[reply]
              • I've re-instated the previous 1st para. --Philcha (talk) 22:58, 12 January 2009 (UTC)[reply]
  • The final sentence of "The clay theory" section seems to dangle. Perhaps it can be merged at the end of the first paragraph?
    • In a "normal" article this would have a para of 3-4 sentences. The scope of this article is so large that I've pruned every part ruthlessly - it would have been easier to write one 3-4 times the size. In this section there are 3 variants of the notion that self-replicating crystalline minerals kick-started biological evolution: (a) Cairns-Smith's original clay->RNA theory; (b) clay->lipid "bubbles", which would have kick-started cell membranes; (c) iron-rich clays kick-started the development of all 3 major components at about the same time. I could combine all 3 paras into one, but this would make it harder for non-specialists to see that there are 3 distinct variants of clay theory. --Philcha (talk) 11:29, 10 January 2009 (UTC)[reply]
  • In the first paragraph on Stromatolites, how does finding a second 3.5 Gyr old Stromatolites negate the criticism? This is unclear to me.
    • The 2nd claim of a find does not negate criticsm of the 1st, and it's an independent move in the debate about the possible presence of life over 3 BYA. I've just found something that might help - it's not a peer-reviwed article, it's an 2007 editorial in Nature (? the most prestigious journal) that says "The existence — or otherwise — of life on Earth in the Archaean eon (prior to 2,500 million years ago) has been a matter of heated debate." I've edited to say explicitly that this is a disputed topic, using the Nature editorial as a ref. The text remains cautious about the 2006 reported find, since by the standards of research in this area there hasn't been enough time see whether it stands up. --Philcha (talk) 11:29, 10 January 2009 (UTC)[reply]
  • Some basic questions seem to be unanswered: What is the role of water in the appearance of life? Why did life evolve to use carbon-based proteins and not something based on sulfur, for example? Don't these seem appropriate topics for an article on evolutionary history?
    • Are you a fellow science fiction fan? I'm no biochemist, but I suspect I could muster enough material to get Alternative biochemistry close to GA level. The trouble with alternative biochemistries is that (a) it's all speculative, no matter how reputable the authors are; (b) there are big debates at all levels, of which the top-level one is probably "carbon chauvinists" vs the rest. Hence it would hard to deal with concisely. For example it would need a mini-essay on why carbon is such a good structural building block and better than silicon, and on the advantages of water over other possible solvents such as ammonia or alcohol. The question of solvents in particular gets into the question of suitable temperature ranges (e.g. would ammonia-based life require such cold conditions that all biological processes, and therefore the pace of evolution, be glacially slow?) and of stellar habitable zones and the relationships between habitable zone, luminosity and stellar life-cycle (would the star's behaviour stay "normal" for long enough?). Assuming alternative biochemistries are viable (which seems unlikely at present), we'd then have to get into why the chemistry of Earth's atmosphere and oceans favoured carbon+water life rather than some other biochemistry - which is very unsafe ground, as views about the chemistry of Earth's atmosphere and oceans keep changing - even for relatively recent times around 1 BYA. Since this article is already long and complex, I think alternative biochemistries would be a step too far. They might be worth considering in the article Abiogenesis. --Philcha (talk) 11:29, 10 January 2009 (UTC)[reply]
      • Rather than a comparison of alternatives, perhaps the article could briefly mention why water and carbon-based chemistry are advantageous to the formation of life? I know it's a lengthy topic, but it seems an essential element to explain why life can appear here.—RJH (talk) 17:49, 11 January 2009 (UTC)[reply]
        • Added as new 1st para of section "Independent emergence on Earth". --Philcha (talk) 23:06, 11 January 2009 (UTC)[reply]
          • I added another sentence and a journal review. Tim Vickers (talk) 23:30, 11 January 2009 (UTC)[reply]
            • Very nice work. Thank you.—RJH (talk) 17:38, 12 January 2009 (UTC)[reply]
  • The microbial mats section doesn't explain why these evolved. Did bacteria evolve as independent organisms first or in mats? Something you might consider for this section is File:Oxygenation-atm.svg, along with an appropriate caption.
    • Re "Did bacteria evolve as independent organisms first or in mats?", that gets into a very complex debate, starting with whether the earliest life on Earth arose in hot environments such as hydrothermal vents or in temperate environments. Then there's the problem of identifying species of fossil bacteria that are over 3 billion yrs old. In addition it's been argued in the context of the Cambrian explosion that until the start of the Cambrian planktonic organisms were too small to sink to the sea-bed, which implies that we'd never find fossils of them. The honest answer is, "That's not known."
    • Some authors assume that mats formed relatively quickly, especially if life started around vents, see Microbial mat. In their opinion symbiosis between organisms that could use each others' by-products as food would have been a strong driving force. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
    • Re File:Oxygenation-atm.svg, there's debate about how fast the O2 content rose - File:Oxygenation-atm.svg takes the view that it was very slow until about 800 MYA, others think it was more even-paced with an initial rise fast enough to cause an Oxygen catastrophe. There are other complications, e.g the initial source of oxygen was cyanobacteria, but if these were in mats the O2 concentration of the water round them would have been higher than that of the atmosphere. Best left to articles on the atmosphere, I think. --Philcha (talk) 15:39, 10 January 2009 (UTC)[reply]
      • Okay.
  • Why nothing about the reasons for the evolution of photosynthesis? Why are photosynthetic organisms green and not black? What about the evolution of predators?
    • Re "reasons for the evolution of photosynthesis", at present that's all speculative, which why I left it out in order to avoid bloat. One conjecture is that life arose round hydrothermal vents and that the precursors of the chemicals that catalyse photosynthesis were infra-red detectors that helped organisms to find or keep the right distance from vents. Then, hypothetically, non-oxygenic photosynthesis evolved. Finally oxygenic photosynthesis was a huge break-through, as it freed ecosystems from dependency on geologically-produced reducing agents, which were becoming scarcer as the Earth's interior cooled, and allowed a huge increase in biological productivity, as its reducing agent is water. Microbial mat covers this, and is cited as a "main article". --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
      • I think I was thrown a little by the introduction of the "modern underwater mats" in the first paragraph of the section. If the mats appeared before photosynthesism, then don't the surface layer bacteria get direct access to, say, the geothermally-vented chemicals? If so, what would be the benefit of having layers?—RJH (talk) 18:09, 11 January 2009 (UTC)[reply]
        • Same as e.g. with mats round hot springs: (a) different organisms flourish at different concentrations of the relevant chemicals (which vary even at mm scale), and some may not tolerate high concentrations of some chemicals; (b) some live off the by-products of others. --Philcha (talk) 21:21, 11 January 2009 (UTC)[reply]
          • Might I suggest moving the sentence about photosynthesizing cyanobacteria down to the start of the paragraph about oxygenic photosynthesis, then inserting a brief sentence in the initial paragraph about the above? I think this would keep related topics together and help explain the emergence of mats. Thank you.—RJH (talk) 17:38, 12 January 2009 (UTC)[reply]
    • Re colours of photosynthetic organisms, I think that's also beyond the scope of this already large article. In fact some oxygenic photosynthesisers are red, e.g. Bangiomorpha mentioned in section "Fossil evidence for multicellularity and sexual reproduction", and some non-oxygenic photosynthesisers are purple, see Microbial mat. The colours of oxygenic photosynthesisers are primarily determined by what wavelengths the two types of chlorophyll absorb and reflect. I remember reading that these do not absorb in the wavelengths that are strongest in sunlight, i.e. they are theoretically sub-optimal, and it's assumed that they are the best that could be produced by the shared biochemical tool-kit of life on Earth. The word "assumed" appears a lot in this discussion because scientists are trying to squeeze the maximum possible information out of very little and often very unclear evidence. Evolutionary history of life avoids the more speculative ideas, mainly in order avoid bloat.--Philcha (talk)
      Okay.
To expand on that, each pigment absorbs over a narrow range. To get a black photosynthetic organism it would have to make a very large number of pigments, which would take a great deal of energy to make - perhaps more than it would gain. However, since no such organism exists, we can't really speculate on its properties and I've never come across any sources that do. Tim Vickers (talk) 23:25, 11 January 2009 (UTC)[reply]
Nice one, Tim! Explains why the The Black Tulip was such a big deal. --Philcha (talk) 23:41, 11 January 2009 (UTC)[reply]
  • Upon reading the multicellularity section, it immediately becomes unclear (to me) why microbial mats are not considered multicellular organisms. Are bacteria composed of two or more unrelated species? Perhaps this can be clarified in the text?
    • I've edited the initial description of mats to "Microbial mats are multi-layered, multi-species colonies ...". In section "Multicellularity", the phrase "having the same genome but different types of cell" rules out mats and other symbiotic ecosystems. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
  • The following sentence seems like self-editorializing: For the sake of brevity this article focusses [sic] on the... "rather anthropocentric". I think it would be better as a note.
    • The problem is that in much of the literature "multicellular" is assumed (that word again!) to refer only to plants, animals and fungi. However there are other, "simpler" organisms that meet the criterion "having the same genome but different types of cell". To deal with that rigorously would require more additional text that I think this article cannot afford, and I have not found in the literature any alternative term that applies to plants, animals and fungi but not to e.g. Volvox or slime moulds. So this article adopts the more wide-spread approach despite its defects, and it's only fair to admit this. The cited source explicity and verbatim describes the more wide-spread approach as "rather anthropocentric". --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
      • I understand. However, the sentence as it exists distracted me from the flow; it is only weakly related to the remainder of the paragraph. This is one of the reasons listed for the use of Wikipedia:Footnotes.—RJH (talk) 18:50, 11 January 2009 (UTC)[reply]
        • I don't know if there's ever been a poll, but I strongly suspect non-specialist readers of science articles quickly learn not to look at refs and footnotes, because the great majority cite literature to which they do not have access. Without a visible explanation some bright kid who's read a pop science book / article about e.g. Volvox or slime moulds (which specialize in the breeding season) will shout "The king's go not clothes". --Philcha (talk) 21:21, 11 January 2009 (UTC)[reply]
          • Okay, I'll drop my objection as it's just a minor issue anyway. Thanks.—RJH (talk)
  • The "Horodyskia" image should be moved down to the next section. Also, the relevance of the caption to the section is unclear.
    • moved, cropped, re-captioned. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
  • The "Plants and the Late Devonian wood crisis" section could explain some other features of plants, such as leaves, vertical growth and bark.
    • Even the most explicit and least technical of the sources (Cowen, p. 120-122), does not mention leaves and bark. The earliest land plants did not have leaves in their current form, and the majority of the big Devonian plants were over-sized ferns and club mosses - now forced into niches (e.g. as opportunists after disasters like the 1980 Mt. St. Helens eruption) by the evolution of tougher competitors) - i.e. no bark."vertical growth" is implied by "photosynthesis was most efficient at the top" and "the parts in between became supports ...". This should be covered in the "main article" Evolutionary history of plants. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
      • Mmm... summary style implies a summarization of the linked main article; in this case the Evolutionary history of plants. You have devoted an entire section to flowering plants, but have little or nothing on leaves and seeds. Even a one-sentence summary would help.—RJH (talk) 18:18, 11 January 2009 (UTC)[reply]
        • Large marine plants such as kelp are virtually all leaf, except that they lack protection against dessication. What was really new was the need for specialised sections in land plants. The lead para of "Colonization of land" says "reproductive systems cannot depend on water to carry eggs and sperm towards each each other", which for plants implies something like seeds (wateerproof), other dispersal mechanisms, etc. "Plants and the Late Devonian wood crisis" mentions Ordovician spores, i.e. first stage in such adaptations. --Philcha (talk) 21:21, 11 January 2009 (UTC)[reply]
          • That works. Thank you.—RJH (talk)
  • In the Land invertebrates section, could the article mention when and why insects developed flight? Is this related to the emergence of flowering plants?
    • Should be covered in an artcle about insect evolution. The problem is that there are multiple hypotheses, and explaining just one of them would require text and diagrams explaining flight anatomy (wings & muscles) and the parts of non-flying insect anatomy that adapted for flight. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
      • Okay. Perhaps it would be permitted to include a one-sentence summary listing the point insects first learned to fly and the primary advantages thereof? It seems too important a detail to leave off.—RJH (talk)
        • Added under "Land invertebrates", with a bonus - "About 99% of modern insect species fly or are descendants of flying species". --Philcha (talk) 23:41, 11 January 2009 (UTC)[reply]
          • Thank you, that looks good.—RJH (talk)
  • Do former land animals that evolved for life at sea deserve mention?
    • I think that would add too much to the article's length:
      • There so many aquatic vertebrates derived from terrestrial forms - mesosaurs, nothosaurs, plesiosaurs (including pliosaurs), ichthyosaurs, mosasaurs, cetaceans, seals, sea lions. In addition there are at least 2 patterns of adaptation, those that still look rather like land vertebrates (most), and those that became fish-like (ichthyosaurs and cetaceans - but we also know how the latter evolved from e.g. Pakicetus).
      • Can't think of land invertebrate lineages that are known to have gone back to the sea, although several arthropods became secondarily aquatic - water spiders, diving beetles, etc., not to mention dragonfly larvae. --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
        • Okay.
  • Shouldn't there be more discussion of ecosystems as drivers of evolutionary history? I see flowering plants and parasitism (as related to sexuality), but it seems like some general discussion might be worthwhile. For example, the formation of soil for land plants, and the evolution of plants as drivers of animal species (apes, insects, &c.).
    • Hmmm. I agree it's an important theme. In addition to "flowering plants and pollinating insects" and the "defence against parasites" theory of sexuality, the article already mentions the symbiotic theory of eucaryote origins (including the "oxygen tides" in microbial mats), the more diverse environments created by multicellular organisms, "Plants and the Late Devonian wood crisis" led to anoxia and the Carboniferous glaciations, how Devonian river conditions may have spurred the development of air-breathing vertebrates. In addition the "Mass extinctions" section points out how extinction made ecological space for other organisms. In fact one of my reasons for re-writing this article is that the previous version was almost all about genetics and paid too litle attention to ecosystems. The question is whether it would be good to summarise these in their own section, for which "Ecosystems as drivers of evolution" would be a good title. I'm inclined (about 75%) to think not:
      • Would increase the length of an already long article.
      • Where to draw the line between biologically and non-biologically driven but evolutionarily important changes in environments? The most difficult case is the Carboniferous glaciations, as the other factor there was that the continents were in the right places to encourage the growth of an ice-cap over the South Pole. The mass extinctions had major effects on ecosystems, producing a mix of set-backs and opportunities, but most were caused by entirely non-biological factors (possibly extra-terrestrial, in the end-Cretaceous extinction, and that's a big enough debate in its own right). --Philcha (talk) 13:37, 10 January 2009 (UTC)[reply]
        • Okay.
  • The caption for File:Opabinia BW.jpg needs a citation. Also, the images File:Acanthodes BW.jpg and File:Acanthostega BW.jpg should be cited if you're taking this for FA. File:Phanerozoic biodiversity blank 01.png has a tag indicating lack of authorship information.

As there are a number of concerns, I'm not sure how readily they can be addressed during the usual review period. Next week I'll check for feedback and put in the GAR ratings. Thanks.—RJH (talk) 23:32, 9 January 2009 (UTC)[reply]

Thank you for your responses. I think they answered most of my concerns, and for the others I added some more comments.—RJH (talk) 18:52, 11 January 2009 (UTC)[reply]
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