Unique Features of Human Skin
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Washington University Record, April 1, 1993
Washington University School of Medicine Digital Commons@Becker Washington University Record Washington University Publications 4-1-1993 Washington University Record, April 1, 1993 Follow this and additional works at: http://digitalcommons.wustl.edu/record Recommended Citation "Washington University Record, April 1, 1993" (1993). Washington University Record. Book 615. http://digitalcommons.wustl.edu/record/615 This Article is brought to you for free and open access by the Washington University Publications at Digital Commons@Becker. It has been accepted for inclusion in Washington University Record by an authorized administrator of Digital Commons@Becker. For more information, please contact [email protected]. WASHINGTON UNIVERSITY IN ST. LOUIS iecord Vol. 17 No. 25 April 1,1993 Architecture class teaches universal design, sensitivity Architecture students recently tried experiencing the world from the perspective of people with disabilities. For a few hours, students maneuvered in wheelchairs, wore blindfolds over their eyes or plugs in their ears to try to get a sense of the needs of people with physi- cal impairments. Some students also spent an entire day in wheelchairs. One took the bus to the St. Louis Galleria, another tried to go out to dinner. For Michele Lewis, a graduate stu- dent in the course, just being at home was difficult. "I even had trouble getting into my building, and there are people living there who are in wheelchairs," she said. "The hallways are too skinny, I couldn't reach my toothbrush and the stove is too high. How are you supposed to know when your water is boiling when you can't see it?" This empathic experience is part of a course taught by Mary Ann Lazarus, vice president at Hellmuth, Obata, and Kassabaum (HOK), an international Sophomore Becky Sladky signs up to be a host for April Welcome, an expanded student recruitment program. -
Getting Under the Skin Regarding the Exact Nature of the Evolutionary Forces That Affected Human Skin Color
BOOK REVIEW Getting under the skin regarding the exact nature of the evolutionary forces that affected human skin color. These arguments make the first six chapters a com- Skin: A Natural History pelling read. Jablonski, as the author, has the advantage of the last word, and strongly promotes her own conclusions, with which some Nina Jablonski may disagree. Nevertheless getting there is an informative journey. University of California Press, 2006 One such evolutionary controversy Jablonski discusses is the ques- tion of why humans evolved dark skin pigmentation after being 281 pp., hardcover, $24.95 exposed to the negative effects of the African sun. What was the selec- ISBN 0520242814 tive pressure that led to epidermal pigmentation as protection? Skin Reviewed by Ian J Jackson cancer is unlikely to be a factor, acting too little (in the case of mela- noma) or too late in reproductive life. Jablonski has long been a proponent of the folate hypothesis. This theory posits that action of ultraviolet radiation on unpigmented skin leads to a catastrophic reduction in folate levels, leading not only to http://www.nature.com/naturemedicine problems in embryonic development but to a range of other adverse Skin looms large in human experience. It is one of the most discussed effects on reproduction. While this may be an appealing hypothesis, aspects of our appearance, and is used by others to assess our health, experimental evidence for photodegradation of folate in vivo has wealth and culture. For example, skin wrinkles and pigmentation pro- been lacking. It is therefore unfortunate that the attention Jablonski vide insight into our age and ancestry. -
Early Members of the Genus Homo -. EXPLORATIONS: an OPEN INVITATION to BIOLOGICAL ANTHROPOLOGY
EXPLORATIONS: AN OPEN INVITATION TO BIOLOGICAL ANTHROPOLOGY Editors: Beth Shook, Katie Nelson, Kelsie Aguilera and Lara Braff American Anthropological Association Arlington, VA 2019 Explorations: An Open Invitation to Biological Anthropology is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted. ISBN – 978-1-931303-63-7 www.explorations.americananthro.org 10. Early Members of the Genus Homo Bonnie Yoshida-Levine Ph.D., Grossmont College Learning Objectives • Describe how early Pleistocene climate change influenced the evolution of the genus Homo. • Identify the characteristics that define the genus Homo. • Describe the skeletal anatomy of Homo habilis and Homo erectus based on the fossil evidence. • Assess opposing points of view about how early Homo should be classified. Describe what is known about the adaptive strategies of early members of the Homo genus, including tool technologies, diet, migration patterns, and other behavioral trends.The boy was no older than 9 when he perished by the swampy shores of the lake. After death, his slender, long-limbed body sank into the mud of the lake shallows. His bones fossilized and lay undisturbed for 1.5 million years. In the 1980s, fossil hunter Kimoya Kimeu, working on the western shore of Lake Turkana, Kenya, glimpsed a dark colored piece of bone eroding in a hillside. This small skull fragment led to the discovery of what is arguably the world’s most complete early hominin fossil—a youth identified as a member of the species Homo erectus. Now known as Nariokotome Boy, after the nearby lake village, the skeleton has provided a wealth of information about the early evolution of our own genus, Homo (see Figure 10.1). -
AMPK Against NASH Non-Alcoholic Steatohepatitis (NASH) Is Activation Were Elevated in LAKO Mice the Most Severe Form of Non-Alcoholic on NASH-Inducing Diets
RESEARCH HIGHLIGHTS collected from people representing published the first report of Journal Club all major global populations. mtDNA mutations causing a The most important discovery of disease — Leber’s hereditary optic mtDNA IN THE CROSSROADS OF their work was that the highest neuropathy. As disease- causing EVOLUTION AND DISEASE degree of mtDNA variation was mutations are amenable to natural found among Africans, attesting to selection, how could one consider Mitochondrial DNA (mtDNA) their anti quity. The other finding the mtDNA to be merely a neutral sequences are currently studied was that although mtDNA from marker? It was this contradiction mainly by three disciplines: across the globe contained African that drew me into studying molecular evolution (including types, Africans had many unique mitochondrial biology and to anthropology), functional mtDNA types. discovering that even common genomics and analyses of genetic These two findings, in addition population variants of mtDNA are disorders. Strangely, these discip- to other data, prompted Cann et al. both subjected to natural selection lines can use the relatively short mtDNA (1987) to propose that the origin and alter the tendency to develop sequence of mtDNA in opposing has been of all current human populations genetic disorders. manners, by attributing to it either considered (at least the maternal lineage) is Dan Mishmar Department of Life Sciences, lack of function, as is the case an excellent likely African. Many criticized in (some) molecular evolution this study, especially because Ben- Gurion University of the Negev, marker for Be’er- Sheva, Israel. studies, or conversely, functional their African samples originated e- mail: [email protected] mainly from Afro-Americans relevance in the aetiology of tracing ancient The author declares no competing interests genetic disorders. -
Why Humans and Their Fur Parted Ways by NICHOLAS WADE (NYT)
August 19, 2003, Tuesday SCIENCE DESK Why Humans and Their Fur Parted Ways By NICHOLAS WADE (NYT) One of the most distinctive evolutionary changes as humans parted company from their fellow apes was their loss of body hair. But why and when human body hair disappeared, together with the matter of when people first started to wear clothes, are questions that have long lain beyond the reach of archaeology and paleontology. Ingenious solutions to both issues have now been proposed, independently, by two research groups analyzing changes in DNA. The result, if the dates are accurate, is something of an embarrassment. It implies we were naked for more than a million years before we started wearing clothes. Dr. Alan R. Rogers, an evolutionary geneticist at the University of Utah, has figured out when humans lost their hair by an indirect method depending on the gene that determines skin color. Dr. Mark Stoneking of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, believes he has established when humans first wore clothes. His method too is indirect: it involves dating the evolution of the human body louse, which infests only clothes. Meanwhile a third group of researchers, resurrecting a suggestion of Darwin, has come up with a novel explanation of why humans lost their body hair in the first place. Mammals need body hair to keep warm, and lose it only for special evolutionary reasons. Whales and walruses shed their hair to improve speed in their new medium, the sea. Elephants and rhinoceroses have specially thick skins and are too bulky to lose much heat on cold nights. -
Recent Human Evolution
A common ancestor at 500 ka? H. heid. in Europe and Africa LCA of Nea. and sapiens? The origin of our species (H. sapiens) TWO origins to explain: 1.The shared (species) features 2. Non-shared (regional/racial) features Origins of modern human behaviour? Complex technology “Houses Networking” Symbolic burials Art Models of modern human origins 1984 1970 1987: Mitochondrial Eve hits the headlines! Mitochondrial DNA and human evolution Nature 325, 31-36 Rebecca L. Cann, Mark Stoneking & Allan C. Wilson (1987) African female ancestor ~200ka The pendulum starts swinging! 2000 1995 1995 1984 1970 The African record H. sapiens: fossils suggest an African origin for the modern pattern ~ 150-200ka? Age ka ~260 ~150? ~160? ~195? >130 Tim White Lieberman Pinnacle Point Howiesonspoort Microliths Klasies Twin Rivers Enakpune Mumba ya Muto Shellfishing Grotta Moscerini Ochre Kapthurin Twin Rivers Klasies Qafzeh Blombos 300 ka 200 150 100 50 0 Taforalt Shell beads Skhul Enakpune Blombos ya Muto Early H. sapiens fossils Omo Kibish Herto “Modern” anatomy and behaviour have deep roots in Africa… ~60 ka: Modern Humans start to leave Africa… ? Out of Africa Mitochondrial DNA Out of Africa Y-chromosome DNA The evolution of regionality (“race”) DNA benetton Natural selection Bottlenecks + Founder Effects Sexual/cultural selection We are all the same (species), but we all look different (individuals, ♀/♂, regions, “races”). Species Individuals (Homo sapiens) large brain Natural Selection body shape high round skull Sexual Selection skin colour small face hair -
Patterns of Human Diversity, Within and Among Continents, Inferred from Biallelic DNA Polymorphisms
Letter Patterns of Human Diversity, within and among Continents, Inferred from Biallelic DNA Polymorphisms Chiara Romualdi,1,2,7 David Balding,3,8 Ivane S. Nasidze,4 Gregory Risch,5 Myles Robichaux,5 Stephen T. Sherry,5 Mark Stoneking,4 Mark A. Batzer,5,6 and Guido Barbujani1,9 1 Department of Biology, University of Ferrara, Ferrara I-44100, Italy; 2 Department of Statistics, University of Padua, Padua I-35121, Italy; 3 Department of Applied Statistics, University of Reading, Reading RG6 6FN, United Kingdom; 4 Max Planck Institute for Evolutionary Anthropology, Leipzig, D-04103 Germany; 5 Department of Pathology, Stanley S. Scott Cancer Center, Louisiana State University Health Sciences Center, New Orleans, Louisiana 70112, USA; 6 Department of Biological Sciences, Biological Computation and Visualization Center, Louisiana State University, Baton Rouge, Louisiana 70803, USA Previous studies have reported that about 85% of human diversity at Short Tandem Repeat (STR) and Restriction Fragment Length Polymorphism (RFLP) autosomal loci is due to differences between individuals of the same population, whereas differences among continental groups account for only 10% of the overall genetic variance. These findings conflict with popular notions of distinct and relatively homogeneous human races, and may also call into question the apparent usefulness of ethnic classification in, for example, medical diagnostics. Here, we present new data on 21 Alu insertions in 32 populations. We analyze these data along with three other large, globally dispersed data sets consisting of apparently neutral biallelic nuclear markers, as well as with a -globin data set possibly subject to selection. We confirm the previous results for the autosomal data, and find a higher diversity among continents for Y-chromosome loci. -
A Rainbow of Sepia: the Evolution of Human Skin Color* by Annie Prud’Homme-Généreux TELUS World of Science – Edmonton, Canada
NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE A Rainbow of Sepia: The Evolution of Human Skin Color* by Annie Prud’homme-Généreux TELUS World of Science – Edmonton, Canada Part I – Why Are People Different Colors? Nina Jablonski, a biological anthropologist at Penn State University, spent many hours thinking about “the sepia rainbow of human skin color.” She knew that our closest primate relatives have pale skin under dark fur, but human skin comes in a variety of shades from pinkish white to dark brown. How did this variation arise? Many biological traits have been shaped by natural selection. Could human skin color be one such trait? If so, she would have to find the selective pressure that caused different populations to evolve varying levels of skin pigmentation. You will now meet Nina in a brief video clip (https://www.hhmi.org/biointeractive/biology-skin-color). She will take you on a journey that she undertook in the pursuit of this question. After you view the video, answer the follow- ing five questions. (Watch until 5:49 min, “Is there a link between the intensity of UV radiation and skin color?”) Questions 1. Describe the conditions necessary for evolution by natural selection to take place in a population. 2. With regard to the evolution of skin color in humans, which of these conditions is Nina sure about (and why?) and which one(s) is she investigating? 3. What is Nina’s likely hypothesis about the evolution of skin color in humans? 4. If her hypothesis is correct, predict the characteristics of the environment where the most heavily pigmented hu- man populations are likely to be found, and the environment where the least pigmented human populations will be found. -
The New Science of Human Evolution - Newsweek Technology -
The New Science of Human Evolution - Newsweek Technology - ... http://www.msnbc.msn.com/id/17542627/site/newsweek/print/1/dis... MSNBC.com The New Science of Human Evolution The new science of the brain and DNA is rewriting the history of human origins. B y Sh ar on Be gl ey Newsweek March 19, 2007 issue - Unlike teeth and skulls and other bones, hair is no match for the pitiless ravages of weather, geologic upheaval and time. So although skulls from millions of years ago testify to the increase in brain size as one species of human ancestor evolved into the next, and although the architecture of spine and hips shows when our ancestors first stood erect, the fossil record is silent on when they fully lost their body hair and replaced it with clothing. Which makes it fortunate that Mark Stoneking thought of lice. Head lice live in the hair on the head. But body lice, a larger variety, are misnamed: they live in clothing. Head lice, as a species, go back millions of years, while body lice are a more recent arrival. Stoneking, an evolutionary anthropologist, had a hunch that he could calculate when body lice evolved from head lice by comparing the two varieties' DNA, which accumulates changes at a regular rate. (It's like calculating how long it took a typist to produce a document if you know he makes six typos per minute.) That fork in the louse's family tree, he and colleagues at Germany's Max Planck Institute for Evolutionary Anthropology concluded, occurred no more than 114,000 years ago. -
The Biology of Skin Color Abbreviated Film Guide Educator Materials
The Biology of Skin Color Abbreviated Film Guide Educator Materials OVERVIEW In The Biology of Skin Color, Penn State University anthropologist Dr. Nina Jablonski walks us through the evidence that the different shades of human skin color are evolutionary adaptations to the varying intensity of ultraviolet (UV) radiation in different parts of the world. Our modern human ancestors in Africa likely had dark skin, which is produced by an abundance of the pigment eumelanin in skin cells. In the high-UV environment of sub-Saharan (or equatorial) Africa, darker skin offers protection from the damaging effects of UV radiation. Dr. Jablonski explains that the variation in skin color that evolved since some human populations migrated out of Africa can be explained by the trade-off between protection from UV and the need for some UV absorption for the production of vitamin D. KEY CONCEPTS A. Biological traits are not inherently good or bad. Some traits can provide an advantage to an organism in certain environments but be a disadvantage in other environments. B. Inherited traits that provide a survival and reproductive advantage in a particular environment are more likely to be passed on to the next generation and thus become more common over time. C. Different human populations living many generations in a particular part of the world may have different variations in certain traits. In spite of these differences, all humans are very closely related and share most traits. D. Evidence from different disciplines, such as anthropology, developmental biology, physiology, genetics, and cell biology, can inform what makes a human trait beneficial or harmful in a particular environment. -
Hair & Hair Growth Desmond J. Tobin 1
Hair & Hair Growth Desmond J. Tobin Hair & Hair Growth Desmond J. Tobin PhD Dir: Centre for Skin Sciences, University of Bradford 1 Structure of presentation Part I • Biologic value of hair: in context of skin & its appendages • Hair follicle: a multi-cell type ‘mini-organ’ • Hair fibre: the hair follicle’s main secreted product • Hair follicle development & growth: a rare example of life-long activity cycling • Hair follicle as regeneration toolkit: stem cells & plasticity Part II • Hair as a sensor: hair follicle is hard-wired to core neuro-endo-immuno axes • Hair follicle pigmentation: an excellent aging model 2 • Hair growth: some common disorders Biologic value of hair: in the context of the skin 3 The screen versions of these slides have full details of copyright and acknowledgements 1 Hair & Hair Growth Desmond J. Tobin Biologic value of skin & hair Skin: • Biologic barrier and the fluctuating environmental interaction • Recognizes, discriminates & integrates signals (via immune, pigmentary & neuroendocrine systems etc.) Hair follicle (HF): • Protection: trauma, radiation, insects, insulation, and cleansing skin surface • Sensory: environment perception, communication (visual, odorant etc.) • Maintenance: reservoir of many regenerative cells types • Immune: anti-microbial upper HF & sebaceous gland 4 I’ve hair, therefore I am…a mammal • Simple HFs: humans, horses, cattle, pigs, sheep, rodents etc. Single hair fiber from single canal. Retained fibers (mouse) • Compound: dogs & cats. Several growing hairs in 1 canal Often 1o or guard fibers with smaller 2o undercoat fibers • Synchronous: wave-like e.g. Most rodents when young • Mosaic: asynchronous – humans, mice etc. with age • Telogenic: most mammals – continuous growth set by seasonality & then efficient retention of telogen hair fibers • Anagenic: rare (wounding response?) ~90% of human scalp HF hair to be cut. -
Mitochondrial Eve and Y-Chromosome Adam: Who Do Your Genes Come From? 28 July 2010
Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? 28 July 2010. Joe Felsenstein Evening At The Genome Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.1/39 Evolutionary trees from molecular sequences from Amrine-Madsen, H. et al., 2003, Molecular Phylogenetics and Evolution Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.2/39 My ancestor? Charles the Great born 747 (Charlemagne) about 44 more generations 1850s Cornelia John Maud William Itzhak Jacob 1880s Helen Will Sheimdel Lev 1910s Eleanor Jake 1942 Joe Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.3/39 Crossing over (recombination) Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.4/39 Did someone at General Motors take a biology course? The GMC Hybrid logo. Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.5/39 Chromosome 1, back up one lineage −6 (none) −5 −4 −3 −2 −1 now Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.6/39 The “mitochondrial Eve” study in 1987 Rebecca Cann, Mark Stoneking, and the late Allan Wilson. In 1987 they made a molecular tree of mitochondria from humans. Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.7/39 One female ancestor? of what? When? Where? Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.8/39 The “Out Of Africa” hypothesis Europe Asia (vertical scale is not time or evolutionary change) Africa Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.9/39 “Scientists find Eve” Mitochondrial Eve and Y-chromosome Adam: Who do your genes come from? – p.10/39 Who was where when Out Of Africa happened? Africa Asia Europe now 100k H.