Talk:Timeline of evolution

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[edit] Date of India/Asia collision

The timeline gives the date of this collision as 22Ma. Previously, the only date I've seen for this event is 50-60 Ma. Thoughts? 140.247.23.113 16:08, 19 March 2007 (UTC)

The Himalayas had formed by at least 40Ma. Verisimilus T 09:34, 13 June 2007 (UTC)

[edit] New study - oldest undisputed evidence

The article to which it refers is Banerjee et al. in Geology 35 (6): 487. I am not yet thoroughly convinced by it. Verisimilus T 09:32, 13 June 2007 (UTC)

[edit] POV

This article makes very bold and definite statements about the dates of early life. Can anybody really put their hand on their heart and say life began at exactly 4Ga? Or that photosynthesis started at 3.5? There's a lot of interesting discussion, that could be placed in the article or elsewhere, about the veracity of this. There should be at least some mention of the arguments involved! Verisimilus T 09:32, 13 June 2007 (UTC)

Do you mean exactly 4 billion years before you wrote that, or before I read it? Obviously it is ridiculous to make any such claim and expect the figure quoted to be precise. However, it is the best estimate we have, and no reasonable reader would expect it to be exact, merely accurate. That the article reports the best figures presently available to science goes without saying. It also links (in the table entry for 4000Ma that you tagged) to the origin of life article which goes in great detail into the question of the date of origin of life on Earth.
Are you sure that "POV" is the correct tag to use? Which POV is being over- (or under-) represented here? SheffieldSteel 13:20, 13 June 2007 (UTC)
By precisely, I mean 4Ga as opposed to 3Ga. Some (Cavalier Smith, I think, is a champion of this cause) exercise the view that since there's no good evidence for life pre-2.7Ga, we oughtn't to assume that there was life at all.
I suppose my qualm would be that a reader of this page would leave with the impression that we know when life appeared - surely it would be better to give a range on the table that reflects reasonable limits imposed by science?
And as far as the dates giving the "best estimate available to science", I agree so far a good date can be given, but I doubt the reliability - sources are definitely required. The 22Ma date for the collision of India and Asia, for example, is plain wrong. Verisimilus T 15:51, 13 June 2007 (UTC)

[edit] Earliest Domesticated Animals

Under 11ka, the article states "Domestication of dogs (first domesticated animal)". I can't find a good reference, but I seem to remember a study which suggested that pigs were actually the first domesticated animals. Does anyone else know anything about this? -Athaler 19:47, 13 July 2007 (UTC)

[edit] What should this page be?

“ This timeline of the evolution of life outlines the major events in the development of life on the planet Earth. ”

At the moment, it reads more as a catalogue of events in Geological and Human history.

I'd propose that it was considerably slimmed, with only the essential points marked, in time order. Trying to provide precise dates is often difficult so ranges should be given where appropriate. My list of events to include, in approximate order, would be:

  • Accretion of Earth
  • Formation of Moon
  • ¿First life?
  • Late heavy bombardment
  • First Photosynthesis
  • First accumulation of atmospheric oxygen
  • First Eukaryote
  • Last Banded iron formations
  • First multicellular life (Bangiomorpha)
  • Sex
  • First complex multicellular life (Ediacaran biota)
  • More oxygenation; enough for ozone
  • Cambrian Explosion
  • First land animals (Eurypterids?)
  • Ordovician radiation
  • First land plants
  • Overview of state of play during Carboniferous
  • Permo-Triassic extinction event
  • Mesozoic marine revolution
  • Gymnosperm forests
  • Rise of dinosaurs
  • First angiosperms
  • Rise of mammals
  • K-T extinction
  • Extensive grasslands
  • Humanity's impact on life

I've deliberately avoided an anthropogenic slant - for example, human evolution should be left to the Timeline of human evolution, to which a see-also should probably be conceded. I also feel that physical constraints and processes - for example, low oxygen levels - should be given higher precedence, as they affect evolution as a whole, not just a small sub-clade of life. Their significance must be explained - as it stands, the reader will wonder why they're being told that Rodinia formed and fragmented, for example. This event may have impacted on the evolution of life - but no clue to this effect is given in the article as it stands!

Please feel free to comment on this list, or my opinions, which I imagine will not be shared by all!

Verisimilus T 20:26, 13 July 2007 (UTC)

With a lack of comment I've pressed on with the trimming. There is now perhaps scope for a little expansion, but I'm wary of creating content forking. I feel that the purpose of this page should be to place events in their context and give an idea of what came when; the place for detailed discussion and description of events is on the pages themselves. The page would, however, benefit from some comments on why each event is relevant to evolution, where this has not been included already. Verisimilus T 17:29, 7 August 2007 (UTC)

Regarding the recent outright reversion of edits: Please feel free to add data that is:

  • Necessary
  • Scientifically accurate, and referenced as such
  • Relevant

It looked like you'd simply undone my edits, although I may be wrong; either way lots of the bogus and inapplicable content appears to have re-emerged... although I'm open to debate! Verisimilus T 15:01, 6 September 2007 (UTC)

  • Hi: I have to say I really dislike what you've done. I have done quite a few edits on this page and find it's current incarnation way to schematic for my tastes. Originally, the page was more a narrative of evolutionary history. I enjoyed filling it out with such things as the first radiation of sharks when I noticed that no one had thought to mention such a major event. The page got so long that I divided it into eons so the tables could be more easily manipulated. But now it looks like a whole bunch of chapter titles with no chapters. I really wish you'd put some content back in. I don't feel inclined to work on this page these days, but that's my firm opinion. Kaimiddleton 08:56, 15 November 2007 (UTC)
    • I agree with Kaimiddleton; a timeline is a valuable method not only for providing an extremely brief overview, but also for providing a somewhat more in-depth chronological look that avoids the limitations of standard prose. However, I also agree with Verisimilus that the previous incarnation of this page was replete with trivia and irrelevencies. I don't see any reason why we can't have our cake and eat it too: if we wish, we can create one shortened page like the current one (but with fixes such as removing the redundant section headers now that it's so short), and another page like the original, lengthy version (but with problems like the anthropocentric focus corrected). Compare pages like List of Latin phrases (full) or Periodic table (large version). Our readers are best-served by providing them with both options, rather than forcing everyone to stick to timeline format for ultra-concise version, and prose format for the slightly more in-depth view, which not only explains when things happened but also what was constituted in each event (e.g., it doesn't merely say "Most modern groups begin to appear in the fossil record during the Cambrian explosion.", but also explains what some of those groups were and provide a little context). -Silence 21:53, 15 November 2007 (UTC)
      • Yes, there's certainly space for a more in-depth history of everything that's ever happened on Earth; maybe it could all be crammed into one page. My problem was with the systematic bias towards the recent and the humanoid. If you're going to list the migration of the grey wolf to North America, should you not also include the migration of the Thelodonts between Estonia and Scotland in the Devonian - and countless other events? The earth's "most recent magnetic reversal" is no more interesting than any of the others; there's little mention of plants, terms such as "the golden age of sharks" are used with no explanation of what that's meant to mean... Certainly, there's room for expansion in the current article, but I think the brief overview gives people a quick guide to the important evolutionary events. Creating an "in depth" page elsewhere sounds an excellent idea, so long as it has a clear rationale - and is scientifically accurate. Verisimilus T 22:27, 15 November 2007 (UTC)

[edit] Problem with timeline

On the timeline, it says all dates prior to 1 billion years are speculative. Technically, if no one was there, aren't all dates prior to humans speculative? —Preceding unsigned comment added by 74.237.134.9 (talk) 22:59, 1 September 2007 (UTC)

I see where you're coming from - but not really. They're based on reliable methods, rather than weak lines of supposition with hints of dubious evidence; their accuracy is there to within a couple of percent, rather than 100%. Besides, there are plenty of dates in human history that are speculative - when was Shakespeare born? Verisimilus T 23:55, 1 September 2007 (UTC)

[edit] Time of Eukaryotes appearance + early evolution part is totally unsourced

Since peroxisomes are thought to have initially developed as a response for the early stages of the Oxygen Catastrophe, it seems odd that eukaryotes appear much later. What is the date of their appearance based about? All the stuff about early evolution is totally unsourced, by the way. Dan Gluck 15:47, 16 September 2007 (UTC)

[edit] Ozone layer formation

According to this article the ozone layer formed 500 millions years ago, when land became habitable (this is what I have always thought)). However in the Oxygen Catastrophe article its formation is related with the much earlier oxygen catastrophe. Is it a real discrepancy, or are we talking about two different phases in its forming (i.e. for a stable 21% oxygen atmosphere one needs a much thinner ozone layer compared to the one needed for the land to become habitable)? Dan Gluck 09:43, 17 September 2007 (UTC)

[edit] Theia?

Should Theia be mentioned here? It has always seemed to me that there are a lot of difficulties with this hypothesis, and the evidence offered so far is equivocal, to say the least. Perhaps it could be included with some indication of evidence to the contrary. --210.240.107.24 (talk) 02:06, 5 March 2008 (UTC)

Sorry, this article does not deal with silly myths. OrangeMarlin Talk• Contributions 02:13, 5 March 2008 (UTC)
In fact, from my understanding, the current coverage of Theia in the article is fair (although one could argue about the semantics). As far as I'm aware, it's quite widely accepted that two "proto-planets" collided to form the Earth and Moon. Verisimilus T 10:48, 5 March 2008 (UTC)
See, I just learned something. I didn't know the myth was used to name the planet. Interesting. OrangeMarlin Talk• Contributions 19:43, 5 March 2008 (UTC)

[edit] Grasses?

There are diferant dates for the evolution of grasses. On The Grasses page there is a third date. Which date is accurate? —Preceding unsigned comment added by 68.230.97.85 (talk) 22:54, 30 March 2008 (UTC)

Picoliths (sp?), small silica shards today found only in grasses, have been found from the late Cretaceous, but are not certain proof that "grasses" existed. The first grass fossils/pollen are (I assume from this article) at 35Ma. Grasses rose to dominance and played an ecologically important role at about 5Ma. Hence the three different dates. Verisimilus T 15:57, 3 April 2008 (UTC)
I independently came across the grasses issue. This article has 'Evolution' in the title, therefore I think the date should reference estimated evolution dates, not times of dominance. I still want to change grasses in the main section to at least 55 mya, but will think on it a while. GameKeeper (talk) 23:20, 12 April 2008 (UTC)
Does the in-text list contribute anything not already present in the diagrammatic timeline? Is it worth keeping? (Especially as it so broad-brush, inaccurate and unreferenced)
Verisimilus T 08:48, 13 April 2008 (UTC)
Yes the in text is far easier to read quickly. much like the summary of articles. GameKeeper (talk) 22:34, 18 April 2008 (UTC)

[edit] Humans 50 millennia old

This article claims modern human facial bone structure evolved 200 millennia ago. This is wrong. Only ape-like creatures that could stand upright evolved by then. Anwar (talk) 19:58, 7 May 2008 (UTC)

Homo sapiens idaltu was pretty human like and lived around 160 millennia ago. I would not describe it as any more ape-like than we are. GameKeeper (talk) 20:25, 7 May 2008 (UTC)