Talk:Human evolution

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Important notice: Some common points of argument are addressed at Wikipedia's Evolution FAQ, which represents the consensus of editors here. Please remember that this page is only for discussing Wikipedia's encyclopedia article about human evolution. If you are interested in discussing or debating evolution itself, you may want to visit Off topic discussions may be deleted on sight.
edit·history·watch·refresh Stock post message.svg To-do list for Human evolution:
  • Add more citations
  • Expand on lead section.
  • Add anatomical cranium comparison chart.
  • Evolution in recent history? (last 200-2000 years)
  • Evolution of speech.
  • Evolution of consciousness / human cognitive evolution.
  • Incorporate Further reading as citations within the text.
Priority 1 (top)

Discuss introduction of cerebellar evolution and its relation to human evolution and encephalization[edit]

The relatively new concept of the cerebellum as a more important organ in the development of the individual including tasks previously attributed to the neocortex makes me think it is time to incorporate this into this part of Wikipedia. Speech is a significant part of the function of the cerebellum amongst other child development and adult ongoing processes. This needs to be considered in the evolution of man along with its other cognitive related functions. I look forward to hearing from you all. — Preceding unsigned comment added by Jobberone (talkcontribs)

The importance of the cerebellum and its contribution to speech and higher cognitive functions as well as emotions, feelings of well being, and pleasure needs to be introduced as possible and even probable contributors into the evolution of hominids. [Special issue: Review, The cerebellum and language: Historical perspective and review, Bruce E. Murdoch, School of Health and Rehabilitation Sciences, The University of Queensland, Australia. [1] 2009]
Jobberone, I disagree. Yes, it should be obvious that language is by far the most important unique feature of humans (no other species spontaneously exhibits grammar), and equally obvious that its development involved changes to the brain. But these changes were certainly not restricted to the cerebellum (which is already well-known to contribute to agility of thought not only of movement); it would be WP:UNDUE (given the current state of neuroscience) to devote a paragraph to the cerebellum and not, for example, Broca's area and Wernicke's area.
There are entire textbooks written on evolutionary neuroanatomy. Our coverage should be founded upon those, not on a single paragraph (about the work of a group decades ago) from one review article which I notice is careless enough as to be guilty of the evolutionary-ladder fallacy: "expanded [reciprocal connections] from the cortex to the cerebellum present in human brains but not in less evolved species" (based on the degree of soft-tissue preservation in fossil hominids we can presume the comparisons were to other modern apes which are in fact no less evolved than us). (Also, other papers by that author have been retracted... This article can work from better sources.)
Lastly, your source says nothing about feelings of wellbeing and pleasure (it barely mentions emotion whatsoever); you seem to be injecting your own views (and writing with an inappropriate tone, e.g. instructing how researchers "need" to act, and predicting which hypothesis will be fruitful). Cesiumfrog (talk) 02:22, 3 November 2014 (UTC)
Now I remember why I don't contribute more to Wikipedia anymore. It's one thing for you to disagree which I welcome but you took it upon yourself to revert my edit which is basically one sentence to allow others to expound on the topic. Why couldn't you post here and wait for me to respond or better for others to chip in?
I agree we not need to get into a detailed neuroanatomical and neurophysiology review but to deny the entire topic of encephalization of the brain one lousy sentence about the cerebellum is ridiculous. Do you have information that the evolution of the cerebellum is NOT important to human evolution? Because if not then you are detracting from the body of work not enhancing it by deletion.
It is noteworthy that the cerebellum has increased in size while the neocortex has decreased since the Pleistocene. There's nothing about the fact the cerebellum increased in size substantially BTW over the last few million years although the neocortex increased moreso. I think this is perhaps the strongest point for discussing it here some. Why does the cerebellum have more neurons than the neocortex? Could that fact have anything to do with our evolution? And yes there is ample evidence the cerebellum is important in pleasure, well being, speech, and attention to tasks.
I don't have a problem with the discussion of other anatomical areas of the brain as long as it is kept very basic and introductory. The cerebellum is a major structure of the brain and not just an area of the neocortex involved in speech or motor function. To get into a more detailed discussion should probably be reserved in an addition of a new topic.
Speech is significantly delayed or aborted in those with cerebellar agenesis. That's important so I don't agree with you it doesn't belong. A paragraph is probably enough here though.
I suggest you add some references rather than bemoan the fact I didn't put enough up. One ref is enough for a sentence or so although a few more would be better.
I'm not going to get into a reversion war with you but I fine your approach here to be unhelpful.
Joberonne, it's clearer if you sign (~~~~) your comments.
We are in agreement that we should improve (and add detail to) the article's treatment of neuroanatomy. I reluctantly removed your good-faith contribution because 1. based on my background knowledge it created a distorted view of the topic (expounding too much weight on fringe ideas while omitting far more important ones), 2. the source was dubious, and 3. much of it was unsupported by the source.
Notice that the human cerebellum has become smaller in proportion to the rest of the brain (even if it is still larger in absolute terms). This might be interpreted to mean that, although the cerebellum is valuable for any brain, it is not a part that was critical to the evolution of humans as distinct from other apes. (Likewise, the total area of the neocortex is also no larger after regressing out the increased volume of the brain as a whole. Likewise lateralisation is not uniquely human. Likewise our number of neurons is not disproportionate for primates.) This is unlike particular areas, such as the pre-frontal cortex, which really did recently evolve to be greater relative to the rest of the brain (displacing sulcal patterns to accommodate it), and so might be more widely interpreted as (potentially) special for human evolution. (Such an interpretation might also be bolstered by the fact that a person born without a cerebellum entirely can still function quite effectively as a human.) It is true that the cerebellum is larger in apes (including us) than in monkeys, but our focus here is more specific than primate evolution.
Some better sources of information would be the books Butler & Hodos Comparative Vertebrate Neuroanatomy: Evolution and Adaptation or Hofman & Falk Evolution of the Primate Brain: From Neuron to Behavior. Cesiumfrog (talk) 12:01, 6 November 2014 (UTC)
I don't think you understand the role of the cerebellum or the fact it has grown considerably as has the neocortex. You are dismissing the role of the cerebellum as it relates to speech as well as it having other roles in our individual development including emotions and cognition. People without a cerebellum have very late speech development if at all and have gross and fine motor dysfunction. They also have cognitive dysfunction. All of these are considerably important to an individual as it is to the evolution of Homo sapiens sapiens and its predecessors. So it certainly should be considered for inclusion. I cannot even fathom why you would object to its inclusion esp one sentence.
I think we can find some mutually agreed upon references although they don't need to be exhaustive. The anatomy, histology, and a lot of the physiology and function of the cerebellum can be gathered from basic texts including the ref I gave which has an adequate bibliography itself. I don't think it appropriate to the topic but you may wish to do some comparative research as to the role of the cerebellum in different phyla and species.
I'm trying to be assertive here but I'm finding it difficult as I have with some prior dealings with you. Now unless you have some information which shows that my contribution to this body of work is non-factual or irrelevant then I'm asking you nicely to either revert it back with any references you feel are necessary or to deal with me in a less dictatorial and dismissive manner here and help the conversation out rather than extinguish it. Can you help me out here?Jobberone (talk) 17:07, 6 November 2014 (UTC)
I have reintroduced a brief introduction of the cerebellum and its possible role in human evolution. I have added three references. There are many many more I could add but too many is cumbersome and not necessary IMO. If you disagree with anything including everything then please be courteous enough to discuss it here without unilaterally just reverting it as before. Thank you.Jobberone (talk) 18:38, 9 November 2014 (UTC)
  • Two of your three sources do not mention evolution whatsoever. These clinical case studies would make useful contributions to the cerebellum article, but are not relevant here.
  • Your remaining source shows that the evolution of the cerebellum has been at a lower rate in humans than what it is in gibbons, orangutans and gorillas (fig.2). It shows that we have no more (in fact slightly less) cerebellum than is expected for any other ape with our sized brain (fig.3). The paper indicates that the cerebellum was important in the divergence of apes from other primates. It presents no reason to suspect that the cerebellum was more significant (than numerous other brain areas) to the divergence of humans from other apes. (Have you considered contributing to the article on primate evolution?)
  • It is true that many decades ago neuroscientists didn't appreciate the cerebellum's non-motor functions. However, in this part of the article, I think sentences discussing the history of neuroscience are straying too far off-topic.
  • If we write "Traditionally the cerebellum has been associated with" instead of "Parts of the cerebellum are sometimes called" then it may sound to the reader as if we don't understand what we're talking about. Why is it relevant to introduce such terms to this article anyway, considering we aren't defining or using them?
Cesiumfrog (talk) 00:29, 10 November 2014 (UTC)
No two don't mention evolution but are there to satisfy basic science and to show what happens without a cerebellum. Prior to the advent of PETI yada either the absence or more commonly infarctions, injuries, etc is all we had to ascertain what the function of organs and parts of organs were and it is still the gold standard. I don't insist they be there but you were the one person who objected to my one source and lack of other sources. First you said these were fringe ideas. Well, I've shown that cerebellar function includes speech and I can provide many more references that show that it is important in cognition as well. This wasn't taught 40 years ago but the body of knowledge relating to other functions of the cerebellum has grown over the last decade plus. This article is not the place for a detailed review of the cerebellum or neocortex nor is it an exhaustive one of human evolution. For the purpose of this article and especially this subtopic of encephalization we only need to briefly discuss the fact the brain and cerebellum got bigger and how that ties in to our evoution. The detailed 'proof' of how we got to where we are via our brains is way beyond the scope of an en encyclopedia. In fact much of the how did it happen is still a matter of conjecture although we all know that the size of the brain as well as the kind and efficiency of processes are important. One final thought. Why is it so important to you to exclude this information from the encyclopedia?Jobberone (talk) 18:30, 10 November 2014 (UTC)
This paper says that human brains have a larger medulla oblongata (which is important for tool use and communication) than other primates. What criteria would you advise to decide whether I should add a paragraph (and how many sentences long) about the medulla to this article? Cesiumfrog (talk) 06:30, 11 November 2014 (UTC)
How does the medulla affect speech, cognition, attention, distraction, or emotions? The answer is it does not. How is the medulla different in primates and especially how is it different in higher primates mostly Homo vs Pan etc? It is not just the fact the cerebellum has increased in size (along with the neocortex) but the fact it increased in size and function enabling the ability of Homo to behave in ways differently than most organisms esp the ability to use tools, speech and social skills. All these would have given early hominids a great deal of advantages over its environment.Jobberone (talk) 23:35, 11 November 2014 (UTC)
Who says it does not? For example, the medulla contains major cranial nuclei which are involved in driving the larynx (speech), and early processing of sensations from the face (human social behaviours), or connect to the hypothalamus/amygdala (emotion), and also contains tracts used for manipulating objects with the hands (tool use). As for the cerebellum, while it is different in apes (compared to other primates) it isn't particularly different in humans (compared to other apes), and thus isn't highly salient to hominin evolution. (Sure, the human cerebellum may have a larger portion of connections to the association cortex, but that is hardly unexpected since the association cortex is the part where the growth of the hominin brain was concentrated.) I suggest a better way to decide how to allocate weight in this section would be to look at current textbooks on hominin evolutionary neuroanatomy, and follow their lead. Cesiumfrog (talk) 03:46, 12 November 2014 (UTC)
I say I know of no information that the brainstem has anything to do with the development of speech. If you have information otherwise then I'd love to see it. AFAIK, the brainstem is autoregulatory although certainly there are pathways thru it. The pathways for touch and proprioception pass thru the nuclei of the medulla. Any modulation and affect on motor response is unknown to me and I don't believe they exist. Furthermore they are not 'cranial' nuclei and they have nothing to do with speech or facial expressions. These are a function of the cranial nerves which arise from the neocortex and are in no way related to the medulla or any part of the primitive brain. The motor control of the hands also has nothing to do with the medulla. So now you are making assertions which are not factual. You keep referring me to textbooks although I was formally studying them 40 years ago. If you have the proper references to refute what I've written then let us all see them so we may act accordingly.Jobberone (talk) 15:06, 12 November 2014 (UTC)

My fear in all of this is that we are putting WP:UNDUE weight on this. I really don't think that, until this is a generally accepted idea, we mention this cerebellum stuff. Dbrodbeck (talk) 17:04, 12 November 2014 (UTC)

I understand this better. This information has been out there for some time; decades for some of it. The relationship to speech and the cerebellum is well known. What's relatively new is the study of the evolution of the cerebellum as it relates to man's evolution. So I don't have a problem 'dialing' this down but not out. I don't see this as an issue of undue weight as we really don't have a great grasp on the neocortex's evolution as it relates to speech and man's technological evolution/ascendence either.
Perhaps a sentence about the evidence of the cerebellum's role in speech and the emerging evidence for cognition and emotions playing a possible role in man's evolution??
It is true there is not wide acceptance nor volume of data for this although I personally believe it must come more into play in the fields of modern medicine as well as paleoanthropology. There is enough evidence, data, and references for a small introductory role now, IMO.Jobberone (talk) 18:24, 12 November 2014 (UTC)
If there is not wide acceptance then really it should not be in the article. Dbrodbeck (talk) 21:33, 12 November 2014 (UTC)
Acceptance was a poor choice of words. Perhaps not as popularly well known is a better choice. But this isn't a popularity contest. This should be science. Does anyone have anything backed by science esp references to be so negative about this? I'd like someone to step up with their own scientific facts and opinions based on that rather than this be a democratic, non-democratic, or beauracratic decision.Jobberone (talk) 01:46, 13 November 2014 (UTC)
Well, then, is it well known in academic circles? Is it a standard thing one sees in textbooks? Dbrodbeck (talk) 01:49, 13 November 2014 (UTC)
Maybe I don't understand the process well enough here. I have 6 years of formal postdoctoral training much of it surrounding this topic. I did my homework and decided to put in a very introductory text. Now one comes in who doesn't even know the subject matter and challenges the minute introduction. Ok. Now one comes and thinks its too much information and undue weight as well as not being broadly accepted. And when I ask for scientific rebuttal I keep getting asked questions about what's out there about it. Don't you think you should be your homework and then ask me specific questions? Do you know the basic science here and the current literature? I don't expect anyone here to be an expert in the field but you should be knowledgeable enough to have an informed opinion. I don't think this topic has to be something that is so well known you were taught it in school. It certainly wasn't taught to me but then a very large volume of information wasn't 20-40 years ago. That is why I think it should be introductory. I realize this is going to sound condescending reading it on a flat screen. That is not how I mean it and I apologize for my awkward approach in advance. I think it fine to bring up the questions but if so then bring some debate with rebuttal rather than questions I've already thought about and put aside.Jobberone (talk) 14:20, 13 November 2014 (UTC)
Hi Jobberone. What we are trying to do here (here being wikipedia) is summarize reliable academic sources. The mainstream academic view. Your credentials, and mine, really don't matter. What matters is sourcing, and secondary sourcing. We don't get to interpret stuff here. Leave that to your academic publishing. Dbrodbeck (talk) 14:42, 13 November 2014 (UTC)
Hi Dbrodbeck. That's very fair and reasonable and is a great goal for the encyclopedia. I agree credentials are not necessary for fair contributions but when someone knowledgeable about the subject thinks we should introduce the material then I find that more palatable than someone who sees a shiny new object and thinks it belongs in the home and has no or inadequate knowledge of the subject matter. It also makes my statements about anatomy and function have a bit more weight. That is all. There is data out there that makes me think this should be introduced. You want to be cautious. That is a good thing.
But if you are going to be cautious you need to state why rather than just say because. I know a reasonable amount of the literature but I'm not knowledgeable enough to say I know everything out there. I haven't discussed this topic with an author although I might. What I'm saying to you is if you think it shouldn't be there then you need to know the literature and give me your reasons. If you want me to give you a thesis or give you a more extensive bibliography then it will have to be here and not in the body of the article. And I will have to decide if I want to give it my attention. I think if you were to try to prove to me why the increase in size of the neocortex caused us to evolve you'd have some problems with it. At some point the cerebellum needs to be a part of the discussion of human evolution. Too many neurons and too much influence on behavior especially speech.Jobberone (talk) 16:55, 13 November 2014 (UTC)

Polyphyletic evolution theories of human races[edit]

Editors may like to review the above article, created 20 December 2014‎ and now at AfD. Johnuniq (talk) 10:06, 2 January 2015 (UTC)

Verification on migration numbers[edit]

I noticed a recent change. Can we get some verification of these numbers that were changed? I looked at the document, doi:10.1002/bies.950181204, authored by Bernard Wood, that is cited, but it doesn't seem to directly support either set of numbers, neither the ones before nor after the change.

Mwatts15 (talk) 20:16, 22 February 2015 (UTC)

I've reverted that edit. Numerical changes by IP addresses without a reasonable explanation should be reverted as a matter of course. In this case the altered numbers probably appear somewhere, but the article would at least have to be updated to show the correct source. Looie496 (talk) 21:44, 22 February 2015 (UTC)

Missing Link gag in cartoons[edit]

  • One storyline of Li'l Abner shows a picture of Li'l Abner identified as "the missing Link" between Ape and man
  • One episode of The Simpsons shows after Homer Simpson going a rampage and then being tranqualized-in which doctors are unsure as to tell of Homer Simpson is a Ape-man or a man-ape! — Preceding unsigned comment added by (talk) 13:53, 3 July 2015 (UTC)

One word: theory[edit]

Evolution is a largely proven theory, yes, but I find this article to be treating it as complete and undisputed fact. Wikipedia is supposed to be unbiased, right? Why do articles on religion still treat them like 'widely disproven theory' and yet articles on atheism and evolution treat an even less proven theory like fact? This needs some review and perhaps some real editing. (talk) 04:49, 10 July 2015 (UTC)

Two words: Scientific theory. Or in slightly more words; "a well-substantiated explanation of some aspect of the natural world that is acquired through the scientific method and repeatedly tested and confirmed through observation and experimentation.". WegianWarrior (talk) 04:58, 10 July 2015 (UTC)
"Evolution" is both a fact and a theory. The fact of evolution is the fact that all complex animals, including humans, evolved from a common ancestor living hundreds of millions of years ago. The theory of evolution is the theory that natural (Darwinian) selection was the primary force driving that process. The fact of evolution is considered by the great majority of scientists to be definitively proven. Looie496 (talk) 11:50, 10 July 2015 (UTC)