Using skills practiced in the Literature review, the student will prepare an Outline essay, which involves developing the essential elements of a good essay in outline form. The Outline essay will involve choosing one of the Outline essay topics, or proposing a topic based on a lecture topic or reading in our unit outline, and preparing an introduction (approximately one page), an outline of evidence and how the argument would be structured (citing the sources), conclusion which discusses the implications, reservations and importance of the argument and a references cited list. The whole document should be less than four pages.
Your introduction and conclusion NEED TO BE DOUBLE SPACED. Your outline and bibliography can be SINGLE-SPACED, but put an extra space in where necessary to make it more readable. The key is readability, but the text portions (intro and conclusion) have to be double-spaced in case we need to write something on your copy.
Topics provided below are general guides; students are encouraged to refine them and make them more specific, as will be clear from the list of topics. A good outline essay will have its own sense of argument. In addition, if a student has a special interest in a topic not listed, but linked to the topics in the Unit Outline, that student is encouraged to propose the topic to the tutor or unit convenor. The only time that we will discourage a topic is if we think that it is unsuitable and will not provide an opportunity to produce a strong Outline essay.
Steps in a producing an outline essay:
1) Choose a topic and start conducting research. Use the same approach from the literature review: locate good sources from peer reviewed journals, read them, see what sources they cite or what has been written since on the same subject (use Web of Science or other academic data base).
2) Start writing immediately! Students often think that they should only write at the end, but this can often be a disaster and form of procrastination. Write something after you read anything interesting.
3) As you go, prepare your bibliography and start arranging your outline page. The outline page should, by the end, but a series of key points, numbered, with a brief note of supporting material (short quotes from authors, citations of the key texts, several facts that would go with the key point if you were to write it up as a paragraph). It must include citations.
Key points are like paragraphs in the body of an essay. So each key point is the collection of material that you think would make a good paragraph. I would expect at least 4 but probably no more than 7 or 8 key points in your outline.
4) Once youve finished with the outline and already have a pretty good bibliography, write the introduction and conclusion. For the introduction, you need to focus on the hook, the thing that draws your reader in and presents the key question, debate or problem you will be discussing. That is, you need to put the key over-arching issue up in the very first long paragraph, giving the reader some sense of why its important.
5) Proofread! When you proofread, reading OUT LOUD is the best way to do it. Cut out things that sound weird, catch yourself repeating words, and trim flabby writing (most essays read smarter when they are shorter). If you cant successfully read something out loud, its not well written; it might be overly convoluted, fragmented, or just a run-on sentence. See the writing advice sheet posted in handouts for the most common writing problems. Presentation MATTERS in this assessment as in everything in life, and the last 10% of effort can translate into a major difference in your final mark, just like the last 100m of a race can lead to a big difference in the outcome. If you get lazy at the very end or dont give yourself enough time, its like putting your resume together and then not caring how it prints out, or preparing for a job interview and then showing up late.
Writing a good introduction
The best way to start an essay is quickly, not to waffle around or present sweeping, overly-broad statements. Bad introductions tend to be padded, overly vague, and dont get to the point until the very end. If youre in the habit of writing your introduction first, you need to get in the habit of going back and fixing it at the end. Its normal to write vaguely at first, but you want to replace this before you turn it in for assessment.
A BAD introduction might start something like, Since time immemorial, humans have wondered what makes humans human. Theyve thought about it, sometimes theyve gone for a walk to think about it, and theyve even done anthropology. The dictionary defines anthropology as Thats a BAD introduction. Its too vague, wastes our time, doesnt actually get to the subject, and frustrates the reader.
A GOOD introduction dives right in, it doesnt waffle around or make vague statements. A good introduction doesnt just summarize the essay (it can, but doesnt have to summarize), but it DOES give the reader a sense of the argument or debate or central question of the essay. For example:
The advent of genetic sequencing presented new evidence about the old question in paleoanthropology: Did neandertals become extinct, or did some of human ancestors interbreed with them? The earliest research on mitochondrial DNA suggested that neandertals died out, leaving no trace in modern populations, but other forms of evidence have supported the opposite argument, that we are, at least in part, their descendants. OR
The fortuitous discovery of the Laetoli footprints provided clear evidence that 3.5 million years ago, hominins were walking upright. Although the discovery helped anthropologists to demonstrate that bipedalism was ancient, however, the footprints did not clarify why humans walked upright. The discovery of the remains of Ardipithecus, in contrast, suggests that we need to understand bipedalism, not as an adaptation, but as an exaptation.
In other words, a good introduction is dynamic and engaging by fronting the central question of the essay. It says, if you like this idea or want to know more, keep reading! You can use a (short) story to get people engaged as long as the story presents the key question or debate, but you dont have to use a story.
Writing a conclusion:
A good conclusion acts like a summary, but it isnt written like one. DO NOT sit down and write, First, I showed that Then, I discussed BORING! Instead, when you finish, ask yourself, If a person only reads two paragraphs in my essay, the introdution and the conclusion, what do I want them to take away from it? Then, write. When you finish that, ask yourself, Why the h*** should anyone care about this? Then, write.
With those notes, you should be able to craft a great conclusion. A good conclusion gives a strong sense of the central argument or thesis of the essay, and it also gives a sense of the significance of the argument, or why anyone should care. A good conclusion makes people go, Yeah, I see that now! and Wow, now that I think about it, this matters! It doesnt make people go, oh, god, Ive already read this.
Choosing good sources:
Students sometimes have trouble figuring out which pieces are reputable and can be trusted, and which cant be. The gold standard for the best research appears in peer-reviewed journals (those which only publish articles after review by other scholars) and in books published by the strongest university presses (rule of thumb: if you havent heard of the university, it may not be the strongest press). There are exceptions, but these are generally the best sources to go on. One way to know that youre NOT dealing with a strong source is that the writer is not referencing their sources; an article without a good references list and either in-text citations or footnotes is almost certainly not one of the best sources.
Try to get some variety in your sources so that you dont wind up only working with one persons opinions (unless thats your specific goal). For example, if you keep finding the same author writing about a topic, consider finding someone who disagrees, to see if the counter-arguments are strong. You may be surprised how some people will continue to drum on about something when other researchers have punched huge holes in their arguments, sometimes continuing with a controversial theory for years.
Also considering getting a variety of journals; focus on peer-review, but dont just quote from the Proceedings of the National Academy of Sciences. Sometimes journals can get in a rut as well, and really interesting, challenging stuff has to come from other journals.
In general, though, remember that these essays are practice for developing your research skills and we want you to demonstrate these skills, not simply choose the easiest, first things you find. If we see a pattern that looks lazy or overly hasty, this will not look good for the assessment.
Integrating your sources into your argument
When working with research, students tend to commit two opposite errors; either they 1) dont make much reference to their sources and dont let the reader know how the argument is supported, or 2) just life whole sections either with or without attribution. Both of these are a problem, and both are pretty obvious when we see them (although were certainly fallible as markers).
Study how other people, whose writing you like, work with their sources and use them. For example, if theres a good article in the reader, notice how the author talks about other peoples ideas, especially if its an article from a good journal (Scientific American, for example, is a bit more popular and doesnt do this well, even though its nice writing). Dont be afraid of referring to authors by their names in the text (you can usually just use last names) and also think about quoting just phrases or terms when theyre particularly good (just put the citation at the end of the sentence).
But make sure you understand something that youre quoting. Often, students will quote paragraphs from a text and then not explain them or tie them into their argument. Sometimes, the paragraph will even say something different to, tangential from, or even opposed to what the student seems to be arguing. This is one of the dangers of over-quoting; make sure that you control the ideas.
Submission and return:
Please pick up a cover form from and submit your essay to the Faculty of Arts Student Centre, W6A Level 1, Foyer of Ground Floor.
The essay is due Wednesday 27 October during Week 11 (this is changed from outline!).
Every effort will be made to return these prior to the final exam; a posting will be made when they are available on the Blackboard unit, and they will be available to be picked up from the Arts Student Centre.
Always keep a copy of your work to avoid any problems if the essay gets misplaced.
For the six assessment criteria, see the last section of the unit outline, Writing Anthropology Essays, and the assessment rubrics, which will be available online.
Why were doing this:
Research skills are an essential part of any university education. Whether youre going into commerce or government or law or engineering or management, youre going to come across questions that force you to go look for answers. We want you to learn how to do this, how to assess sources of information or arguments, and how to report your findings. Even if your job title does not say, researcher, youre likely to find that you will want to have these skills, to be able to up-skill yourself and teach yourself about new subjects.
The essay outline format makes you do the research work, and to focus on the key areas of introducing the concepts and discussing significance, without making your mark just about your writing skills. One danger with essays is that people with good writing skills often get high marks, even though their research skills do not improve. In contrast, if people have a hard time with writing, they can get marked down for their writing even though theyve done the crucial legwork and understand the sources.
Although this essay outline does not do away entirely with either problem, it makes your mark more contingent upon your research skills and doesnt force you to spend the majority of your time on the finer points of writing. Collecting material, arranging it into an outline of a single page, allows you to concentrate on the material and its organization, not the final form or polishing.
Sample outline essay topics:
1. Among evolutionary theorists, primatologists, and anthropologists, debate rages about what makes humans distinct from other species. Make the case for one criterion as the important distinction between humans and other animals, drawing on scientific sources.
2. Comparative primatology is one important source of information about human evolution. Using only data from comparative primatology, discuss what theorists can know about one of the following issues: human sexuality, reproduction, social relations, perceptual abilities, bipedalism, or large brain size.
3. The origin of bipedalism is controversial for a number of reasons, including the fact that the potential evolutionary advantages offered by moving on two feet are numerous, but no single one is clearly, decisively the most obvious candidate for being the primary selective pressure. Briefly outline the case for and against three distinct theories about the origin of bipedalism. With the word limit, you will need to be concise.
4. From an evolutionary standpoint, is culture adaptive or maladaptive? You will likely want to offer multiple reasons, and you are free to suggest reasons that it might be considered both.
5. Sometimes, evolutionary psychologists argue that every trait of human beings must offer some advantage to our species, or else natural selection would have eliminated that trait from our species. What are several reasons that traits which are not necessarily an advantage in survival or reproduction might persist in a species?
6. What does evolutionary theory suggest about human nature? Find a definition of human nature by a philosopher or other theorist and discuss several of the traits or characteristics that are seen as part of human nature. Are they consistent with what we have learned about human evolution and evolutionary theory more generally? Does the definition create any problems in light of the evidence about human evolution?
7. Evolutionary theory is often poorly understood in the general public. Choose from one to three key concepts in evolutionary theory (for example, survival of the fittest, species, evolution, genes, or natural selection) and discuss how these concepts are misunderstood in public debates. You are strongly advised to seek out editorials, Creationist websites, discussions by scientific race theorists and evolutionary psychologists, and similar repeat offenders, but you may also run across inaccurate discussions even in basic science news.
8. What is the significance of human diversity our variation in appearance, sexuality, abilities, behaviour, and other characteristics for the survival and evolution of our species? Is it likely that humans will grow more or less similar over time? Is it likely that we will change over time, or evolve into some new species?
9. Neandertals are likely to be among our closest extinct ancestors. Debate rages about whether they should be considered a separate species, or a sub-species of humans. Using scientific evidence, make the case one way or the other and discuss the significance of both the debate, and your position specifically.
HERE IS AN EXAMPLE ~~
An understanding of the evolution of bipedalism in Hominini is underpinned by two fundamental questions; the locomotor characteristics of the last common ancestor (LCA) of Pan and Homo, and the selective forces that favoured progression from occasional to obligate bipedalism. Early hypotheses were based on limited fossil material and the locomotory modes, and phylogenetic proximity, of extant African apes. They focused on the increasing use of the forelimbs for non-weight-bearing functions (e.g., tool use) as an explanation for the development of bipedalism from a knuckle-walking ancestor (Harcourt-Smith 2007). Although some (Begun et al. 2007) still argue for knuckle-walking as a precursor, recent evidence (Kivell & Schmitt 2009; Lovejoy & McCollum 2010; Tallman 2012) supports the hypothesis that knuckle-walking was not a locomotory mode within the hominin lineage. Late Miocene hominids were more likely to have displayed an orthograde posture with generalized locomotory behaviours (Harcourt-Smith 2007) including arboreal bipedalism (Thorpe et al. 2007).
The oldest conclusive evidence of hominin bipedalism, the Laetoli footprints, dates the appearance of an efficient human-like gait to at least 3.6 Mya (Raichlen et al. 2010). The morphological evidence from early hominin fossil remains, Sahelanthropus tchadensis (6.87.2 Mya), Orrorin tugenensis (5.76 Mya) and Ardipithecus ramidus (4.4 Mya) implies a far earlier terrestrial bipedalism (Harcourt-Smith 2010) close to the divergence time of Pan and Homo. Palaeoenvironmental data indicates a progressive drying, cooling trend from the Late Miocene with an increasingly mosaic environment of reduced forest and increased open grassland (Harcourt-Smith 2007). The environmental changes led to the savannah hypothesis: bipedalism was an efficient terrestrial locomotory mode between dispersed resources (Harcourt-Smith 2010). This hypothesis was questioned with the realisation that early hominins were associated with forest environments not open grasslands (Senut 2006b). Related to the savannah hypothesis are the thermoregulatory advantages of a bipedal, especially exposure to direct solar radiation (Wheeler 1991). Harcourt-Smith (2007) argues that the evolution of bipedalism was a two stage process. The skeletal characteristics of the early hominins suggest both bipedal and arboreal locomotion, with the first shift to habitual bipedalism in Australopithecines. While the evidence suggests a modern human-like gait (Raichlen et al. 2010) in Australopithecus afarensis, it retained arboreal adaptations. The second stage, a shift to obligate bipedalism, is associated with the genus Homo.
Outline
1. Skeletal and trace fossil evidence for bipedalism in early hominins.
Laetoli footprints (circa 3.6 Mya), earliest trace fossil evidence of hominin bipedalism, kinematically similar to modern humans (Raichlen et al. 2010). Position of foramen magnum in S. tchadensis interpreted as indicator of bipedalism (Harcourt-Smith 2010). Femoral features of O. tugenensis cluster with Australopithecines rather than apes or humans suggesting bipedality (Pickford et al. 2002; Richmond & Jungers 2008). Plesiomorphic forelimb morphology implies arboreal climbing. Ar. ramidus: pelvic, femoral and lumbar spinal morphology are indicative of upright bipedalism, but retention of arboreal climbing (Lovejoy & McCollum 2010; Lovejoy, Suwa et al. 2009).
2. Palaeoenvironments associated with early hominins and the origin of terrestrial bipedalism.
As Senut (2006b) points out, locomotory behaviours need to be considered within their palaeoenvironmental context. Orrorin has been associated with thick vegetation and forest, Ardipithecus with woodlands (Lovejoy 2009); in contrast the Laetoli footprints appear in a mosaic environment of savannah and thicker vegetation (Senut 2006a). Implications: a drying trend over time, but the critical point is that bipedalism originated in well-wooded habitats rather than savannah (Pickford 2006).
3. Hominini and the question of a knuckle-walking ancestor.
Forelimb modifications in extant African apes associated with knuckle-walking are not present in Ar. ramidus (Lovejoy & McCollum 2010). The evidence for knuckle-walking has been refuted (Tallman 2012). Kivell & Schmitt (2009) concluded that knuckle-walking in African apes is convergent and not homologous. The evidence strongly supports the argument against a knuckle-walking Pan – Homo LCA.
4. Likely locomotory repertoire of the Pan – Homo LCA and the arboreal bipedalism hypothesis.
Though controversial, hipbone morphology in the Late Miocene ape Oreopithecus bambolii (79 Mya) suggests a locomotory repertoire that included bipedalism (Rook et al. 1999). Ardipithecus, and by implication the LCA, exhibited none of the adaptations to below-branch suspension, knuckle-walking, or vertical climbing that characterise both extant African apes (Sayers et al. 2012, p. 125). Lumbar spinal mobility permits upright stance with extended hip and knee in Ardipithecus and LCA (Lovejoy & McCollum 2010). Thorpe et al. (2007) argued for orthograde clambering and hand-assisted arboreal bipedalism, extrapolated from orangutan locomotion behaviours (Crompton, Vereecke et al. 2008; Crompton, Sellers et al. 2010).
5. Locomotor efficiency and the savannah hypothesis.
Sockol et al. (2007) compared human walking vs. quadrupedal and bipedal locomotion in chimpanzees, found that human walking was 75% more energy efficient. Modelling of bipedal gait in Au. afarensis (Pontzer et al. 2009), Laetoli footprints (Raichlen et al. 2010) and the absence of a bent-hipbent-knee gait in Ardipithecus (Lovejoy & McCollum 2010), argues for gait economy in early hominins.
6. Thermoregulatory benefits of bipedalism in an open environment.
Bipedal vs. quadrupedal posture reduces exposure to solar radiation and increases convective cooling (Wheeler 1991). A more significant hypothesis in the open savannah associated with late Australopithecines and Homo, particularly with persistence hunting (Liebenberg 2006).
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Conclusion
Humans are unique in their specialisation to essentially one form of locomotion, as opposed to the broad mosaic of locomotory behaviours seen in other primates. In many respects our understanding of the evolution of human bipedalism is strongly influenced by comparative primatology, and potentially suffers from the use of the African apes as referential models (Sayers et al. 2012). The potential for preservation of behaviours is limited, there are no Laetoli footprints to inform us of the locomotory behaviours of the LCA and the earliest hominins, and we needs rely on the examination of fossils to interpret function from form. Despite these limitations logical conclusions can be inferred from the current evidences.
In the absence of a knuckle-walking ancestor, the most parsimonious view for the LCA of Hominini is a generalist orthograde-clambering Late Miocene ape that included arboreal bipedalism in its locomotory repertoire. Although as Harcourt-Smith (2007, p. 1490) points out it is rather limited to single out one particular locomotor mode as the likely precursor to habitual hominin bipedalism. However, it is safe to assume that this locomotion was an exaptation for terrestrial bipedalism in Orrorin, Sahelanthropus and Ardipithecus. The retained arboreal skeletal traits and environments associated with these early hominins implies the continued utilisation of trees as supplementary food sources and safety from predators (Senut 2006b). Considered from the evolutionary viewpoint of competitive exclusion, Panini maintained its forest habitat evolving into a specialist frugivore, while Hominini evolved as a more adaptable terrestrial omnivore. Ultimately, the adoption of bipedality in a wooded environment would have facilitated the hominin invasion of open environments (Pickford 2006).
Considering the highly derived nature of human bipedalism and its associated skeletal characteristics there must have been strong selection pressures that specifically required prolonged periods of upright walking (Harcourt-Smith 2007, p. 1507). Of the many proposed explanations for the selection of bipedalism (e.g. tool-carrying, male provisioning, thermoregulation) an energy efficient mode of locomotion, possibly associated with foraging, appears the most robust. Given the palaeoenvironmental trends during the Plio-Pleistocene, it may be easier to argue for an increased efficiency hypothesis for the shift to obligate bipedalism. However, as Rodman & McHenry (1980, p. 105) argued in their paper on the relative efficiency of human bipedalism, It is not necessary to posit special reasons such as tools or carrying to explain the emergence of human bipedalism, although forelimbs free from locomotor function surely bestowed additional advantages to human walking.
References
Begun, D.R., Richmond, B.G. & Strait, D.S. 2007. Comment on \”Origin of human bipedalism as an adaptation for locomotion on flexible branches\”. Science, 318(5853): 1066.
Crompton, R.H., Vereecke, E.E. & Thorpe, S.K.S. 2008. Locomotion and posture from the common hominoid ancestor to fully modern hominins, with special reference to the last common panin/hominin ancestor. Journal of Anatomy, 212(4): 501543.
Crompton, R.H., Sellers, W.I. & Thorpe, S.K.S. 2010. Arboreality, terrestriality and bipedalism. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1556): 33013314.
Harcourt-Smith, W.E.H. 2007. The Origins of Bipedal Locomotion. In Henke, W. & Tattersall, I. (eds), Handbook of Paleoanthropology. Springer-Verlag, Berlin. Chap. 5, pp. 14831518.
Harcourt-Smith, W.E.H. 2010. The first hominins and the origins of bipedalism. Evolution: Education and Outreach, 3(3): 333340.
Kivell, T.L. & Schmitt, D. 2009. Independent evolution of knuckle-walking in African apes shows that humans did not evolve from a knuckle-walking ancestor. Proceedings of the National Academy of Sciences, 106(34): 1424114246.
Liebenberg, L. 2006. Persistence hunting by modern hunter-gatherers. Current Anthropology, 47(6): 10171026.
Lovejoy, C.O. 2009. Reexamining human origins in light of Ardipithecus ramidus. Science, 326(5949): 74, 74e174e8.
Lovejoy, C.O. & McCollum, M.A. 2010. Spinopelvic pathways to bipedality: why no hominids ever relied on a bent-hipbent-knee gait. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1556): 32893299.
Lovejoy, C.O., Suwa, G., Spurlock, L., Asfaw, B. & White, T.D. 2009. The pelvis and femur of Ardipithecus ramidus: the emergence of upright walking. Science, 326(5949): 71, 71e171e6.
Pickford, M. 2006. Paleoenvironments, Paleoecology, Adaptations, and the Origins of Bipedalism in Hominidae. In Ishida, H., Tuttle, R., Pickford, M., Ogihara, N. & Nakatsukasa, M. (eds), Human Origins and Environmental Backgrounds. Springer, US, pp. 175198.
Pickford, M., Senut, B., Gommery, D. & Treil, J. 2002. Bipedalism in Orrorin tugenensis revealed by its femora. Comptes Rendus Palevol, 1(4): 191203.
Pontzer, H., Raichlen, D.A. & Sockol, M.D. 2009. The metabolic cost of walking in humans, chimpanzees, and early hominins. Journal of Human Evolution, 56(1): 4354.
Raichlen, D.A., Gordon, A.D., Harcourt-Smith, W.E.H., Foster, A.D. & Haas Jr, W.R. 2010. Laetoli footprints preserve earliest direct evidence of human-like bipedal biomechanics. PLoS ONE, 5(3): e9769, 16.
Richmond, B.G. & Jungers, W.L. 2008. Orrorin tugenensis femoral morphology and the evolution of hominin bipedalism. Science, 319(5870): 16621665.
Rodman, P.S. & McHenry, H.M. 1980. Bioenergetics and the origin of hominid bipedalism. American Journal of Physical Anthropology, 52(1): 103106.
Rook, L., Bondioli, L., Khler, M., Moy-Sol, S. & Macchiarelli, R. 1999. Oreopithecus was a bipedal ape after all: evidence from the iliac cancellous architecture. Proceedings of the National Academy of Sciences of the United States of America, 96(15): 87958799.
Sayers, K., Raghanti, M.A. & Lovejoy, C.O. 2012. Human evolution and the chimpanzee referential doctrine. Annual Review of Anthropology, 41(1): 119138.
Senut, B. 2006a. Arboreal Origin of Bipedalism. In Ishida, H., Tuttle, R., Pickford, M., Ogihara, N. & Nakatsukasa, M. (eds), Human Origins and Environmental Backgrounds. Springer, US, pp. 199208.
Senut, B. 2006b. Bipdie et climat. Comptes Rendus Palevol, 5(12): 8998.
Sockol, M.D., Raichlen, D.A. & Pontzer, H. 2007. Chimpanzee locomotor energetics and the origin of human bipedalism. Proceedings of the National Academy of Sciences, 104(30): 1226512269.
Tallman, M. 2012. Morphology of the distal radius in extant hominoids and fossil hominins: implications for the evolution of bipedalism. The Anatomical Record, 295(3): 454464.
Thorpe, S.K.S., Holder, R.L. & Crompton, R.H. 2007. Origin of human bipedalism as an adaptation for locomotion on flexible branches. Science, 316(5829): 13281331.
Wheeler, P.E. 1991. The thermoregulatory advantages of hominid bipedalism in open equatorial environments: the contribution of increased convective heat loss and cutaneous evaporative cooling. Journal of Human Evolution, 21(2): 107115.
HERE IS ANOTHER EXAMPLE~~
In light of recent genetic and archaeological research, the debate concerning genetic mixing between Neanderthals and anatomically modern humans (AMHs) has moved from whether interbreeding occurred to when, where and for how long it took place. The idea of Neanderthals being direct ancestors of Homo sapiens has been considered since the hominid was first discovered, however until recently the scientific consensus has largely been that as AHMs left Africa and colonised the globe, resulting in the complete replacement (CR) of all other hominids (Stringer & Andrews, 1988). According to that theory, Neanderthals – once widespread and ecologically dominant – were rendered extinct by the presence of AHMs approximately 30,000 year ago. Despite early genetic evidence supporting a CR scenario, subsequent archaeological and genetic data is increasingly establishing a very different sequence of events (Green et al., 2010; Condemi et al., 2013). Genetic studies have established that Neanderthals contributed 1-4% to the present day genetic diversity of all people except populations originating from sub-Saharan Africa (Sankaraman, 2012). Of this gene flow, East Asians carry 40% more Neanderthal DNA than Europeans, indicating the nature of AMH/Neanderthal interaction is more complex than previously thought (Wall et al., 2013) and involved prolonged interbreeding and/or successive waves of AMHs migrating out of Africa. Archaeological evidence supporting an interbreeding hypothesis has been found across multiple sites in Europe and Asia, indicating stabilised populations of hybrid hominids (Condemi et al., 2013; Smith, Jankovic & Karavanic, 2005; Duarte et al., 1999). It is argued that in light of mounting evidence, Neanderthals were a subspecies of Homo sapiens rather than a separate species of hominid. Though contributing a relatively small amount of genetic material, it is clear Neanderthals did not go extinct in the classical sense. Rather, Neanderthals were likely genetically swamped by their AMH cousins and absorbed into the invading populations of AMHs as they colonised Europe and Asia.
1 CR model has been popular (Stringer & Andrews, 1988). Specimens showing what looks to
be hybridisation – such as Lagar vehlo child (Duarte et al., 1999) have been dismissed as parallel evolution or retention of primitive traits (Aiollo, 1993). Demise of Neanderthals attributed to some variant of a competitive exclusion scenario (Banks et al., 2008; Herrera et al., 2008). Generally researchers concede some genetic mixing cannot be ruled out and state additional genetic material is needed to draw firmer conclusions (Stringer & Andrews, 1988; Aiollo, 1993; Krings et al., 1997; Herrera, 2008). Early genetic evidence from Neanderthals backs up Complete Replacement Model but is based on only a single Neanderthal specimen (Krings et al., 1997).
2 With a draft sequencing of the Neanderthal genome comes evidence of a higher rate of
genetic similarity between Neanderthals and non-Africans compared to Africans (Green et al., 2010). Likely cause is attributed to gene flow from Neanderthals to AMHs at some point after AMHs left Africa and before the divergence of Europeans, East Asians, and Papuans, resulting in 1-4% of present day human genes having Neanderthal origin (Green et al., 2010; Eriksson & Manica, 2012).
3 A Counter explanation to genetic similarity is that an ancient underlying genetic structure
present before the split of what would become AMHs and Neanderthals that is reflected by the genetic similarities recently established (Eriksson & Manica, 2012). This theory is often mentioned as unlikely but not able to be ruled out by theorists supporting an assimilation type model, detailed below (Green et al., 2010; Sanchez-Quinto et al., 2012). However this explanation does not account for archaeological specimens implying hybridisation.
4 Neanderthal genes give weight to the existing Assimilation model of Neanderthals being
genetically swamped and absorbed into the invading AMH populations over a period of perhaps tens of thousands of years (Smith, Jankovic & Karavanic, 2005; Sankaraman et al., 2012). If Neanderthals interbred with AMHs and were (at least partially) absorbed into the AMH population then they were not a distinct species and therefore did not go extinct (Smith et al., 2005).
5 Additional archaeological evidence of early European AMHs showing Neanderthal-like traits
and late European Neanderthals with AMH-like traits is indicative of a prolonged period of interbreeding and bilateral gene flow (Smith et al., 2005; Condemi et al., 2013).
6 Recent more thorough analysis of the Neanderthal genome adds further complexity to
identifying the time period and location(s) in which interbreeding took place. Neanderthals DNA compared to genetic array of present day humans in Northern Africa moves the earliest interbreeding to before AMHs left Africa (Sanchez-Quinto et al., 2012).
7 Wall et al. (2013) make use of the high-coverage Denisova genome (Meyer, 2012) to show
present-day East Asian and European populations differ in genetic similarity to Neanderthals. East Asians carry 40% more Neanderthal genetic material implies interbreeding must have occurred (or continued) after the separation of these populations. These additional data necessitate a more complex scenario of interaction and interbreeding between Neanderthals and AMHs. Wall et al.s results also undermine the possibility of ancient African genetic substructure being the reason behind genetic similarity, as the populations leaving Africa would have homogenous levels of similarity.
Conclusion
Rather than a simple scenario of one or two incidents of interbreeding, the current genetic and archaeological research implies a more complex and prolonged period of genetic mixing between Neanderthals and AMHs. Recent interpretations suit a period of interbreeding spanning tens of thousands of years as AMHs migrated out of northern Africa, spreading throughout Asia and Europe. It seems the more that is learned about the fascinating period in which AMHs and Neanderthals co-existed, the more nuanced the picture becomes. If Neanderthals and AMHs interbred then no true speciation occurred between the populations as they diverged; genetic difference only reached a level of subspecies. If this conclusion is firmly established, the taxonomy must be adjusted accordingly. Accounting for genetic similarities as being due to an ancient African genetic substructure in a common ancestor appears unlikely, particularly due to a discrepancy in the genetic similarities of East Asian and European populations when compared to Neanderthals. Additional data is needed to rule out a substructure explanation. Further research into this area of study will benefit from interdisciplinary cooperation due to the multifaceted nature of the area. Primarily genetic and archaeological research will continue to contribute to understanding along with other approaches including anthropological, chronological and spatial population dynamics (Langley, Clarkson & Ulm, 2008; Eriksson & Manica, 2012). Combined, an interdisciplinary approach will create a more robust and well-rounded picture of these ancient hominids. As the theoretical landscape is influenced by the fast changing mosaic of research data as it accumulates, the complex saga that was the relationship between AMHs and Neanderthals is revealed. A relationship that seems to have included instances of interbreeding resulting in hybridisation, cultural exchange, multiple waves of AMHs migrating out of Africa and ongoing gene flow after the split of Asian and European populations. This field of research speaks in a fundamental way to who we are and how we have come to be.
References
Aiello, L. C. 1993. The Fossil Evidence for Modern Human Origins in Africa: A Revised View. American Anthropologist, 95 (1), 73-96
Banks, W. E., dErrico, F., Townsend Peterson, A., Kageyama, M., Sima, A. & Sanchez-Goni, M. 2008. Neanderthal Extinction by Competitive Exclusion. PLoS one, 3 (12), e3972
Condemi, S., Mounier A., Giunti, P., Lari, M., Caramelli, D. & Longo, L. 2013. Possible Interbreeding in Late Italian Neanderthals? New Data from the Mezzena Jaw (Monti Lessini, Verona, Italy). PLoS one, 8, e59781
Duarte, C., Mauricio, J., Pettitt, P. B., Sauto, P., Trinkaus, E., van der Plicht, H. & Zilhao, J. 1999. The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia. PNAS, 96, 7604-7609
Eriksson, A. & Manica, A. 2012. Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins. PNAS, 109 (35), 13956-13960
Green, R. E., Krause, J., Briggs, A. W., et al. & Pbo, S. 2010. A Draft Sequence of the Neandertal Genome. Science 328, 710-722
Herrera, K. J., Somarelli, J. A., Lowery, R. K. & Herrera, R. J. 2008. To what extent did Neanderthals and modern humans interact? Biological Review, 84, 245-257
Krings, M., Stone, A., Schmitz, R. W., Krainitzki, H., Stoneking, M. & Paabo, S. 1997. Neandertal DNA Sequences and the Origin of Modern Humans. Cell, 90, 19-30
Langley, M. C., Clarkson, C. & Ulm, S. 2008. Behavioural Complexity in Eurasian Neanderthal Populations: a Chronological Examination of the Archaeological Evidence. Cambridge Archaeological Journal 18 (03) 289-307
Meyer, M., Kircher, M., Gansauge, M., et al. & Pbo, S. 2012. A High-Coverage Genome Sequence from an Archaic Denisovan Individual. Science, 338, 222-226
Sanchez-Quinto, F., Botigue, L. R., Civit, S., Arenas, C., Avila-Arcos, M. C., Bustamanta, C. D., Comas, D. & Lalueza-Fox, C. 2012. North African Populations Carry the Signature of Admixture with Neandertals. PLoS one, 7 (10), e47765
Sankaraman, S., Patterson, N., Li, H., Paabo, S. & Reich, D. 2012. The Date of Interbreeding between Neandertals and Modern Humans. PLoS One, 8(10), e1002947
Smith, F. H., Jankovic, I. & Karavanic, I. 2005. The assimilation model, modern human origins in Europe, and the extinction of Neandertals. Quaternary International, 137, 7-19
Stringer, C. B. & Andrews, P. 1988. Genetic and Fossil Evidence for the Origin of Modern Humans. Science, 239 (4845), 1263-1268
Wall, J. D., Yang, M. A., Jay, F., Kim, S. K., Durand, E. Y., Stevison, L. S., Gignoux, C., Woerner, A., Hammer, M. F. & Slatkin, M. 2013. Higher Levels of Neanderthal Ancestry in East Asians than in Europeans. Genetics, 194, 199-209
