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14.6: End of Chapter Content

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    For Further Exploration


    Baptista, Vander. 2006. “Starting Physiology: Understanding Homeostasis.” Advances in Physiology Education 30: 263–264.

    Goldstein, David S., and Bruce McEwen. 2002. “Allostasis, Homeostats, and the Nature of Stress.” The International Journal on the Biology of Stress 5 (1): 55–58.

    General Clinal Variation and Genetic Exchange

    Delhey, Kaspar. 2019. “A Review of Gloger’s Rule, an Ecogeographical Rule of Colour: Definitions, Interpretations and Evidence.” Biological Reviews 94 (4): 1294–1316.

    Feng, Yuanqing, Michael A. McQuillan, and Sarah A. Tishkoff. 2021. “Evolutionary Genetics of Skin Pigmentation in African Populations.” Human Molecular Genetics 30 (R1): R88–R97.

    Hu, Hao, Nayia Petousi, Gustavo Glusman, Yao Yu, Ryan Bohlender, Tsewang Tashi, Jonathan M. Downie, et al. 2017. “Evolutionary History of Tibetans Inferred from Whole-Genome Sequencing.” PLoS Genetics 13 (4): e1006675. .

    Jablonski, Nina G. 2021. “Skin Color and Race.” Special issue, “Race Reconciled II: Interpreting and Communicating Biological Variation and Race in 2021,” American Journal of Physical Anthropology 175 (2): 437–447.

    Pritchard, Jonathan K., Joseph K. Pickrell, and Graham Coop. 2010. “The Genetics of Human Adaptation: Hard Sweeps, Soft Sweeps, and Polygenic Adaptation.” Current Biology 20 (4): R208–R215.

    Sankararaman, Sriram, Swapan Mallick, Nick Patterson, and David Reich. 2016. “The Combined Landscape of Denisovan and Neanderthal Ancestry in Present-Day Humans.” Current Biology 26 (9): 1241–1247.

    Lactase Persistence

    HHMI BioInteractive. 2021. “The Making of the Fittest: Got Lactase? The Co-evolution of Genes and Culture.” Accessed April 7, 2023.

    Malaria and Sickle Cell Anemia

    Bill and Melinda Gates Foundation. 2022. “Malaria.” Accessed April 7, 2023.

    Centers for Disease Control and Prevention. 2022. “Malaria.” Accessed April 7, 2023.

    HHMI BioInteractive. 2020. “The Making of the Fittest: Natural Selection in Humans.” 2020. Accessed April 7, 2023.

    National Institutes of Health: National Center for Advancing Translational Sciences. “Sickle Cell Anemia.” Accessed April 7, 2023.

    World Health Organization. 2022. “Malaria.” Accessed April 7, 2023.

    Rickets and Bone Health

    National Institutes of Health: National Center for Advancing Translational Sciences. “Rickets.” Accessed April 7, 2023.

    Talmadge, D. W., and R. V. Talmadge. 2007. “Calcium Homeostasis: How Bone Solubility Relates to All Aspects of Bone Physiology.” Journal of Musculoskeletal and Neuronal Interactions 7 (2): 108–112.

    Skin Color

    HHMI BioInteractive. 2020. “The Biology of Skin Color.” Accessed April 7, 2023


    American Academy of Pediatrics, Task Force on Infant Sleep Position and Sudden Infant Death Syndrome. 2000. “Changing Concepts of Sudden Infant Death Syndrome: Implications for Infant Sleeping Environment and Sleep Position.” Pediatrics 105 (3): 650–656.

    Beja-Pereira, Albano, David Caramelli, Carles Lalueza-Fox, Cristiano Vernesi, Nuno Ferrand, Antonella Casoli, Felix Goyache, et al. 2006. “The Origin of European Cattle: Evidence from Modern and Ancient DNA.” PNAS 103 (21): 8113–8118.

    Best, Andre, Daniel E. Lieberman, and Jason M. Kamilar. 2019. “Diversity and Evolution of Human Eccrine Sweat Gland Density.” Journal of Thermal Biology 84: 331–338.

    Bigham, Abigail W. 2016. “Genetics of Human Origin and Evolution: High-Altitude Adaptations.” Current Opinion in Genetics & Development 41: 8–13.

    Centers for Disease Control and Prevention. 2017. “Data & Statistics on Sickle Cell Disease.” Centers for Disease Control and Prevention website, August 9. Accessed April 7, 2023. .

    Crawford, Nicholas G., Derek E. Kelly, Matthew E. B. Hansen, Marcia H. Beltrame, Shaohua Fan, Shanna L. Bowman, Ethan Jewett, et al. 2017. “Loci Associated with Skin Pigmentation Identified in African Populations.” Science 358 (6365): 1–49.

    Cyrkalff, Marek, Cecilia P. Sanchez, Nicole Kilian, Curille Bisseye, Jacques Simpore, Friedrich Frischknecht, and Michael Lanzer. 2011. “Hemoglobins S and C Interfere with Actin Remodeling in Plasmodium falciparum-Infected Erythrocytes.” Science 334 (6060): 1283–1286.

    Dzialanski, Zbigniew, Michael Barany, Peter Engfeldt, Anders Magnuson, Lovisa A. Olsson, and Torbjӧrn K. Nilsson. 2016. “Lactase Persistence versus Lactose Intolerance: Is There an Intermediate Phenotype?” Clinical Biochemistry 49 (2016): 248–252.

    Fernando, Sumadya D., Chaturaka Rodrigo, and Senaka Rajapakse. 2010. “The ‘Hidden’ Burden of Malaria: Cognitive Impairment Following Infection.” Malaria Journal 9 (366): 1–11.

    Gerbault, Pascale, Anke Liebert, Yuval Itan, Adam Powell, Mathias Currat, Joachim Burger, Dallas M. Swallow, and Mark G. Thomas. 2011. “Evolution of Lactase Persistence: An Example of Human Niche Construction.” Philosophical Transactions of the Royal Society B: Biological Sciences 366 (1566): 863–877.

    Gray, Olivia A., Jennifer Yoo, Débora R. Sobriera, Jordan Jousma, David Witnosky, Noboru J. Sakabe, Ying-Jie Ping, et al. 2022. “A Pleiotropic Hypoxia-Sensitive EPAS1 Enhancer Is Disrupted by Adaptive Alleles in Tibetans.” Science Advances 8 (47): 1–13.

    Hartman, T. K., S. J. Rogerson, and P. R. Fischer. 2013. “The Impact of Maternal Malaria on Newborns.” Annals of Tropical Paediatrics 30 (4): 271–282.

    Longo, Dan L., Frédéric B. Piel, Martin H. Steinberg, and David C. Rees. 2017. “Sickle Cell Disease.” The New England Journal of Medicine 376 (16): 1561–1573.

    Maddux, Scott D., Todd R. Yokley, Bohumil M. Svoma, and Robert G. Franciscus. 2016. “Absolute Humidity and the Human Nose: A Reanalysis of Climate Zones and Their Influence on Nasal Form and Function.” American Journal of Physical Anthropology 161 (2): 309–320.

    Meyer, M. C., M. S. Alexander, Z. Wang, D. L. Hoffmann, J. A. Dahl, D. Degering, W. R. Haas, and F. Schlütz. 2017. “Permanent Human Occupation of the Central Tibetan Plateau in the Early Holocene.” Science 355 (6320): 64–67.

    Moore, Lorna G., Susan Niermeyer, and Stacy Zamudio. 1998. “Human Adaptation to High Altitude: Regional and Life-Cycle Perspectives.” Yearbook of Physical Anthropology 41: 25–64.

    Noback, Marlijn L., Katerina Harvati, and Fred Spoor. 2011. “Climate-Related Variation of the Human Nasal Cavity.” American Journal of Physical Anthropology 145 (4): 599–614.

    Peacock, A. J. 1998. “ABC of Oxygen: Oxygen at High Altitude.” BMJ 317 (7165): 1063–1066.

    Pontzer, Herman, Mary H. Brown, Brian M. Wood, David A. Raichlen, Audax Z.P. Madbulla, Jacob A. Harris, Holly Dunsworth, et al. 2021. “Evolution of Water Conservation in Humans.” Current Biology 31 (8): 1804–1810.

    Quillen, Ellen E., Heather L. Norton, Esteban J. Parra, Frida Loza-Durazo, Khai C. Ang, Florin Mircea Illiescu, Laurel N. Pearson, et al. 2019. “Shades of Complexity: New Perspectives on the Evolution and Genetic Architecture of Human Skin.” Yearbookof Physical Anthropology 168 (S67): 4–26.

    Ranciaro, Alessia, Michael C. Campbell, Jibril B. Hirbo, Wen-Ya Ko, Alain Froment,

    Paolo Anagnostou, Maritha J. Kotze,

    et al. 2014. “Genetic Origins of Lactase Persistence and the Spread of Pastoralism in Africa.” American Journal of Human Genetics 94 (4): 496–510.

    Roby, Brianne Barnett, Marsha Finkelstein, Robert J. Tibesar, and James D. Sidman. 2012. “Prevalence of Positional Plagiocephaly in Teens Born after the ‘Back to Sleep’ Campaign.” Otolaryngology—Head and Neck Surgery 146 (5): 823–828.

    Sherman, Paul W., and Jennifer Billing. 1999. “Darwinian Gastronomy: Why We Use Spices.” BioScience 49 (6): 453–463.

    Tishkoff, Sarah A., Floyd A. Reed, Alessia Ranciaro, Benjamin F. Voight, Courtney C. Babbitt, Jesse S. Silverman, Kweli Powell, et al. 2007. “Convergent Adaptation of Human Lactase Persistence in Africa and Europe.” Nature Genetics 39 (1): 31–40.

    World Health Organization. 2021. “World Malaria Report 2021.” World Health Organization website, December 4, 2022. Accessed April 7, 2023.

    Zhang, Xinjun, Kelsey E. Witt, Mayra M. Bañuelos, Amy Ko, Kai Yuan, Shuhua Xu, Rasmus Nielsen, and Emilia Huerta-Sanchez. 2021. “The History and Evolution of Denisovan-EPAS1 Haplotype in Tibetans.” PNAS Biological Sciences 118 (22): 1–9.

    Image Description

    Figure 14.3: When exposed to cold temperatures, basal metabolic rate increases, shivering begins and vasoconstriction helps maintain heat near the core of the body where the vital organs are located. When exposed to warm temperatures above 35 degrees celsius, vasodilation occurs and excess body heat is lost through sweating.

    Figure 14.4: Vasoconstriction is the constriction of peripheral capillaries in the skin. The decreased surface area of the capillaries through vasoconstriction results in less heat reaching the surface of the skin where it would be dissipated into the atmosphere. The opposite happens with vasodilation, where the peripheral capillaries in the skin are closer to the surface of the skin so that heat can be dissipated into the atmosphere, thereby cooling the body.

    Figure 14.10: Melanocytes are melanin-producing cells located in the bottom layer of the skin’s epidermis. Located in the central part of the epidermis, melanosomes are packets of color made by melanocytes. In light skin, melanosomes are small, with little pigmentation. In larger skin, they are larger and darkly pigmented. The differences in pigmentation are also due to differences in the distribution of melanosomes within the keratinocytes.

    Figure 14.12: Evolution of Skin Color Variation:

    1. Hair and Skin: Once hominins lost most of their body hair they likely had dark pigmented skin. In environments with high UV radiation, dark skin protected early humans against skin damage.
    2. Folate and UV Rays: UV rays penetrate the skin and can break down folate in the bloodstream. Folate is necessary for sperm production and for fetal development.
    3. Leaving Africa: Once some humans left Africa, they encountered environments with different levels of UV radiation. New selective pressures began to shape human skin color among these groups.
    4. Vitamin D: In low UV environments, people with dark skin could not synthesize enough vitamin D resulting in rickets and other health problems. People with dark skin had a lower chance of survival in most of these environments.
    5. Selective Pressures: Vitamin D, folate and changing UV environments were the selective pressures that resulted in the development of a variety of skin colors in different populations throughout the world.

    Figure 14.19: Life cycle of the malaria parasite: The mosquito injects the parasites when it bites the human. The parasites grow and multiply first in the liver cells and then in the red cells of the blood. In the blood, successive broods of parasites grow inside the red cells and destroy them, releasing daughter parasites (“merozoites”) that continue the cycle by invading other red cells. The blood stage parasites are those that cause the symptoms of malaria. When certain forms of blood stage parasites (gametocytes, which occur in male and female forms) are ingested during blood feeding by a female mosquito, they mate in the gut of the mosquito and begin a cycle of growth and multiplication in the mosquito. After 10-18 days, a form of the parasite called a sporozoite migrates to the mosquito’s salivary glands. When the Anopheles mosquito takes a blood meal on another human, anticoagulant saliva is injected together with the sporozoites, which migrate to the liver, thereby beginning a new cycle. (Adapted from Malaria: Biology: Lifecycle by the CDC).

    Figure 14.21: Map of the eastern hemisphere shows locations of different red blood cell abnormalities:

    • Thalassemia: most of Africa, Mediterranean, and SE Asia,
    • HbS: most of sub-Saharan Africa and smaller regions of the Mediterranean, Middle East, and India,
    • HbC: western Africa,
    • Ovalocytosis: parts of southeast Asia,
    • HbE: parts of south Asia, and
    • Pk deficiency: much of Europe.

    Figure 14.22: The effects of human horticultural activities on the balancing selection of populations in relation to sickle cell disease genotype variants: Humans arrive and clear the land to grow crops. Slash and burn horticulture leads to pools of stagnant water. Mosquitos flourish in the pools of water. Malaria increases as a result. Individuals with the sickle cell allele HbS are better at fighting malaria, leading to its increased frequency in the population. Balancing selection occurs in populations with both malaria and high incidences of sickle cell disease (from the HbSS genotype).

    Figure 14.23: A map of the eastern hemisphere with shading illustrating the population frequencies of adults with lactase persistence. Shades range from very light in populations with little lactase persistence (0-10%) to very dark (90-100%). Low frequencies were more common in southern Africa and southeastern mainland Asia. Frequencies were higher in western Africa, the Arabian Peninsula, and most of Europe. The highest frequencies were in northern Europe.

    This page titled 14.6: End of Chapter Content is shared under a CC BY-NC 4.0 license and was authored, remixed, and/or curated by Leslie E. Fitzpatrick (Society for Anthropology in Community Colleges) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.