The Effects of Cold Adaptation on the Growth and Development of the Neandertal Cranial Base
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Illinois State University ISU ReD: Research and eData Theses and Dissertations 5-30-2014 The Effects Of Cold Adaptation On The Growth And Development Of The Neandertal Cranial Base Sarah Caldwell Illinois State University, [email protected] Follow this and additional works at: https://ir.library.illinoisstate.edu/etd Part of the History of Art, Architecture, and Archaeology Commons, and the Paleontology Commons Recommended Citation Caldwell, Sarah, "The Effects Of Cold Adaptation On The Growth And Development Of The Neandertal Cranial Base" (2014). Theses and Dissertations. 195. https://ir.library.illinoisstate.edu/etd/195 This Thesis is brought to you for free and open access by ISU ReD: Research and eData. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of ISU ReD: Research and eData. For more information, please contact [email protected]. THE EFFECTS OF COLD ADAPTATION ON THE GROWTH AND DEVELOPMENT OF THE NEANDERTAL CRANIAL BASE Sarah J. Caldwell 92 Pages August 2014 Neandertals and modern humans possess very different craniofacial shapes. Some recent work has attributed these contrasting shapes specifically to differences in brain development, which are extrapolated to mean differences in cognitive function. However, this may not necessarily be the case. In this paper, it is suggested that a size increase in the cranial base and rapid cranial growth are due not to cognitive differences, but environmental factors, specifically Neandertal adaptation to cold. Adaptation to cold would not only explain the more rapid growth of the Neandertal cranium, but also elongation of the cranial base via elongation of the nasopharynx for maximizing air conditioning capabilities. The results indicate a closer relationship between Neandertals and cold-adapted modern humans than either of these groups with the other two considered (early modern humans and warm-adapted modern humans). While all variables in the cranium are correlated to some degree, cranial base length is most strongly correlated with measures of facial projection. This indicates that, along with some other factors, elongation of the cranial base greatly affects projection of the face; this could be caused via elongation of the nasopharynx due to cold-adaptation. Cold adaptation early in Neandertal children would have prepared them for the harsh environment that they are born and raised in, allowing for a higher chance of survival in a harsher environment. Thus, environmental factors are considered a valid argument for the differing shapes and developmental trajectories of Neandertals and modern humans. THE EFFECTS OF COLD ADAPTATION ON THE GROWTH AND DEVELOPMENT OF THE NEANDERTAL CRANIAL BASE SARAH J. CALDWELL A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Department of Sociology and Anthropology ILLINOIS STATE UNIVERSITY 2014 Copyright 2014 Sarah J. Caldwell THE EFFECTS OF COLD ADAPTATION ON THE GROWTH AND DEVELOPMENT OF THE NEANDERTAL CRANIAL BASE SARAH J. CALDWELL COMMITTEE MEMBERS: Fred H. Smith, Chair Maria O. Smith ACKNOWLEDGMENTS I would be lying if I said that writing a thesis was my favorite past time, though I also would not be giving the endeavor enough credit if I said that I wasn’t extremely grateful to have had the opportunity to do so. My biggest thanks can go to none other than Dr. Fred Smith, my advisor and chair, for taking a chance on me and for his guidance, which has been truly invaluable. I don’t think I could have asked for a better graduate mentor. Dr. Maria Smith also deserves my sincerest thanks for her never ending willingness to discuss all manner of things scientific, her assistance, and constant encouragement. Dr. Steven Juliano has been an incredible help with the statistics that I legitimately could not have performed or interpreted without his guidance. And finally, my undergraduate advisor, Dr. Don Gaff, also deserves my appreciation. I was no longer his responsibility and he still proofread everything I sent to him with minimal resistance. I also cannot conclude without thanking my friends who tolerated my obsessiveness and encouraged me without hesitation. My most heartfelt thanks go to Rob Lewis, Kayla Yario, Dan Dawson, and Jamie Thomas. I also must thank my fellow graduate students who experienced/suffered through/reveled in this experience with me: Deb Neidich, Katie Lacy, Ian Fricker, Cori Rich, Alison Hodges, Ian Fricker, Jeff Painter, Sarah Boncal, Andrew Mallo and Scott Drapalik. S. J. C. i CONTENTS Page AKNOWLEDGMENTS i CONTENTS ii TABLES iv FIGURES vi CHAPTER I. INTRODUCTION 1 II. REVIEW OF RELATED LITERATURE 3 Introduction to Neandertals 3 Integration of the Cranium 11 Structure of the Cranial Base 12 Ontogeny of the Basicranium 13 Structure of the Splanchnocranium 15 Ontogeny of the Splanchnocranium 16 Interactions between the Cranial Base and the Face 17 Evidence of Cold Adaptation in the Cranium 17 III. MATERIALS 21 IV. METHODS 24 Cranial Measurements 24 Statistical Methods 26 V. RESULTS 30 ii Mean Values for Cranial Measurements 30 Pearson Correlations 35 Canonical Output for Cold Group vs. Warm Group 37 Canonical Output for Cold Group vs. Neandertals 38 Canonical Output for Warm Group vs. Neandertals 40 Canonical Output for Neandertals vs. Early Modern Humans 42 Canonical Output for Cold Modern vs. Early Modern Humans 43 Canonical Output for Warm Modern vs. Early Modern Humans 44 Canonical Output for All Modern Humans vs. Archaic Humans 45 Canonical Output for All Humans vs. Neandertals 46 Contrasts 47 VI. SUMMARY 52 VII. DISCUSSION 54 Neurocranial Dimensions 54 Splanchnocranial Developments 57 Neandertal Upper Respiratory Tract 62 Neandertal Growth 64 Splanchnocranial Growth 65 Neurocranial Growth 67 VIII. CONCLUSIONS 69 REFERENCES 73 iii TABLES Table Page 1. Samples Chosen from W.W. Howells Collection 22 2. Adult Neandertals 22 3. Adult Anatomically/ Early Modern Humans 23 4. Means, Standard Error, and Range for Cranial Base Length 30 5. Means, Standard Error, and Range for Cranial Breadth 31 6. Means, Standard Error, and Range for Cranial Height 32 7. Means, Standard Error, and Range for Facial Projection 33 8. Means, Standard Error, and Range for Facial Height 34 9. Neandertal Cranial Correlations 35 10. Early Modern Human Cranial Correlations 36 11. Cold-Adapted Modern Human Cranial Correlations 36 12. Warm-Adapted Modern Human Cranial Correlations 36 13. MANOVA Test Criteria: Cold-Adapted MH vs. Warm-Adapted MH 37 14. Canonical Coefficients for Cold-Adapted MH vs. Warm-Adapted MH 38 15. MANOVA Test Criteria: Cold-Adapted MH vs. Neandertals 39 16. Canonical Coefficients for Cold-Adapted MH vs. Neandertals 39 17. MANOVA Test Criteria: Warm-Adapted MH vs. Neandertals 40 18. Canonical Coefficients for Warm-Adapted MH vs. Neandertals 41 iv 19. MANOVA Test Criteria: Neandertals vs. Early MH 42 20. Canonical Coefficients for Neandertals vs. Early MH 42 21. MANOVA Test Criteria: Cold-Adapted MH vs. Early MH 43 22. MANOVA Test Criteria: Warm-Adapted MH vs. Early MH 44 23. Canonical Coefficients for Warm-Adapted MH vs. Early MH 44 24. MANOVA Test Criteria: Modern Humans vs. Archaic Humans 45 25. Canonical Coefficients for Modern Humans vs. Archaic Humans 46 26. MANOVA Test Criteria: Humans vs. Neandertals 46 27. Canonical Coefficients for Humans vs. Neandertals 47 28. Contrasts with Dependent Variable – log Cranial Base Length 47 29. Contrasts with Dependent Variable – log Cranial Height 48 30. Contrasts with Dependent Variable – log Cranial Breadth 49 31. Contrasts with Dependent Variable – log Facial Projection 50 32. Contrasts with Dependent Variable – log Facial Height 51 v FIGURES Figure Page 1. Cranial Base Anatomy 1 2. Neandertal and Modern Human Cranial Comparison 6 3. Cranial Base Flexure and Synchondroses Location 13 4. Cranial Measurements 25 5. LSMeans for Cranial Base Length 31 6. LSMeans for Cranial Breadth 32 7. LSMeans for Cranial Height 33 8. LSMeans for Facial Projection 34 9. LSMeans for Facial Height 35 10. Influential Variables – Cold-Adapted MH vs. Warm-Adapted MH 38 11. Influential Variables – Cold-Adapted MH vs. Neandertals 40 12. Influential Variables – Warm-Adapted MH vs. Neandertals 41 13. Influential Variables – Early MH vs. Neandertals 43 14. Influential Variables – Early MH vs. Warm-Adapted MH 45 15. Nasopharyngeal Anatomy 61 vi CHAPTER I INTRODUCTION The basicranium plays a critical, multifaceted role in cranial structure and development. It is the foundation of the skull and is composed of parts of five bones: portions of the occipital, the right and left temporal bones, the sphenoid, and the entire ethmoid (see Figure 1). Figure 1: Cranial Base Anatomy - This figure shows the structure of the cranial base, as well as other major features. The frontal appears in pink, ethmoid in purple, the sphenoid in yellow, temporals as the paired purple bones, and the occipital is grey (OpenStax, 2013). The darkened area represents the cranial base. 1 The resulting construct connects the skull with the vertebral canal and anchors the splanchnocranium to the neurocranium. It performs many functions, including providing safe passage for cranial nerves and the brain stem and maintaining conduits for the circulation system of the brain. It is affected by, and has profound effects on, various aspects of the development of the cranium. In Neandertals, this cranial base is elongated, especially in the anterior portion (Smith, 1991; Trinkaus, 2003); however, what exactly this means for the development of the Neandertal