Human Evolution Exam 1 Study Guide
Human Evolution Exam 1 Study Guide ANTH-UA 2
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This 12 page Study Guide was uploaded by Mallori Albright on Sunday October 9, 2016. The Study Guide belongs to ANTH-UA 2 at New York University taught by Scott Alan Williams in Fall 2016. Since its upload, it has received 192 views. For similar materials see Human Evolution in Anthropology at New York University.
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Date Created: 10/09/16
Anthropology: the study of the evolution and culture of humans and other primates. Subfields are biological, sociocultural, linguistics, and archaeology. • Primate: member of mammalian order; primates defined by series of traits (all shared) • Hominin: member of our (direct) lineage —humans and their fossil ancestors after their evolutionary split from apes • Hominid: humans and great apes • Evolution: change in the frequency of a gene or trait over generations (descent with modification) • Culture: the sum total of a group’s learned traditions • Biological anthropology: study of evolution as it relates to human species, diversity, or indirectly o Osteology: study of skeletal biology o Paleoanthropology: study of fossil record of ancestral humans and primate relatives o Bio archaeology: study of human remains in archaeological context o Forensic anthropology: study of human remains applied to a legal context o Primatology: study of living, non -‐human primates and anatomy, genetics, behavior, and ecology o Human biology: study of human growth and development, adaptation and variation, nutrition o Molecular anthropology: study of genetics in humans and non -‐human primates • Sociocultural anthropology; study of human societies in cross -‐cultural perspective o Theory § Ethnology: the comparison of e thnographies (cross-‐cultural) § Ethnography: description of customs of individual people or cultures o Study topics: colonialism, nationalism, gender and sexuality, feminism, religion, politics and law, media, etc. • Linguistic anthropology: study of language; it s origin and use • Archaeology: study of material culture of past peoples o Artifacts: the objects; from tools to art , left by earlier groups of people o Historical: written records and traditions and prehistorical archaeology Vertebrates: animals with a backbon e; Tetrapods: vertebrates with limbs; Amniotes: tetrapods with an amniotic egg (amnion). Incomplete list of shared derived traits to know for the exam: o Mammals: o Mammary glands (not all mammals have nipples) o Hair (all mammals have hair) o Heterodonty (differentiation of teeth) Primates o All primates derived traits: o Nails o Grasping hands and feet o Derived traits: st o 1 digit opposability § Pollex on hand § Hallux on foot (not humans) o Convergent orbits and postorbital bar or closure o Reduced snout and olfactory bulb o Increase in overall brain size. st 1 major division of primates: Lemurs and lorises o Strepsirrhines (wet noses) o Grooming/toilet claw (hind limb) o Tooth comb: 4 teeth at lower jaw for grooming 2 major division of primates: Tarsiers and anthropoids 1. Tarsiers o Nocturnal o Haplorrhines (dry nose) o Loss or rhinarium o Increased postorbital closure (partial closure in tarsiers) o Because they have no eye shine, they have big eyeballs 2. Anthropoids o Closed orbit (complete postorbital closure) o Further increase in brain size. o Old World monkeys and apes o Catarrhines: loss of a premolar § Dental formula: 18.104.22.168 § Cercopithecoids: tall, crested (bilophodont) molars [vs. hominoids, which have simple, rounded molars] o Apes and/including humans (hominoids): § Loss of tail § Upright body plan • Mobile shoulder • Wrist joints • Long arms • Short trunk/torso. Summary of primate biogeography • Lemurs: Madagascar • Lorises: Mainland African and SE Asia • Tarsiers: SE Asia • New World monkeys: Central & South A merica • Old World monkeys: Africa and Eurasia • Nonhuman apes: o Gibbons and orangutans: SE Asia o Gorillas, chimpanzees, bonobos: Africa Mating systems Monogamy • Pair-‐bonded groups (male, female, dependent offspring) o Lifetime monogamy: mating pairs are stable over lifetime o Sexual monogamy: mating pairs are stable over breeding season o Relatively rare in mammals (less than 59%; common in birds, more than 90%) • Primate example: o Gibbons Polygyny • Polygamy: any mating system that’s not monogamy o 1 male, multi-‐female o Most common mammalian patterns o 2 main types in primates: § Female defined polygyny: males guard cluster of females (“harem”) • Primate example: gorillas § Dispersed mating (solitary) • Can be polygynandry • Primate example: orangutans Polyandry • 1 female, mutli-‐male • Primate example: o Some marmosets and tamarins o Facultative polyandry o Related to twinning? Polygynandry • Mutli-‐male/multi-‐female • Promiscuous mating (loaded term) • Primate example: o Chimps and bonobos o Macaques Primate diets: most primates are generalists; diet affects day/home range • Fruit (Frugivory) o Patchy distribution in time and space (some trees =fruit, some don’t; depends on season) o Easy to digest o High carbs, low protein • Seeds (Gramnivory) o Tougher to process • Flowers/nectar (Nectivory) o Like fruit, patchy in time and space (similar to fruit) • Leaves and stems (Folivory) o High protein, low carbs o Abundant (more than fruit) but harder to digest • Exudates—gum and sap (Gumnivory) o Requires specialized feeding adaptations (tusk -‐like incisors) • Tubers, roots, bulbs, etc. o Important for savannas o Requires work to acquir e and ingest (dig; difficult to digest) • Animal matter (Faunivory) o Includes invertebrates and vertebrates o Good source of energy but hard to catch • Other o Grass (grass seeds) § Geladas o Bark § Orangutans Body size and diet: • Larger animalsàabsolutely more food, relatively less energy, lower quality foods (leaves) • Small animalsàabsolutely less food, relatively more energy, highe r quality foods (e.g., insects) Primate biomes and environments Tropical biomes • Majority of primate species • Largely defined by latitude (ne ar equator) Tropical rainforest • Defined by latitude and rainfall • No water and summer—just rainy seasons • Always some trees fruiting all year round Tropical seasonal forests • More variable rainfall throughout year • Some trees will lose leaves • Less extensive canopy Other tropical biomes occupied by primates • Savanna o Grasslands with some trees/shrubs o Primates only found in African savannas • Woodlands, thorn woods, shrub lands o Areas between forest and savanna • Habitats based on water o Coastal o Mangrove o Swamp o Riverine • Bamboo forests Temperate biomes • Very few genera found outside tropics o Some macaques: Japanese snow monkeys and Barbary macaques o Some leaf-‐eating monkeys Why are primates social? Why live in groups? • Anti-‐predation strategies o Increased vigilance (awareness) o Cooperative defense § “mobbing” (group defense) o Alarm calls o Dilution effect (so many; predator’s confused and can’t focus on one) o “selfish herd” (healthy animals protected; leave older, or young, animals) o predator confusion • Foraging: finding and accessing food o More eyes to find food o More efficient foraging o Competition for resources § Defense of takeover of food patches/territory § Cooperation in hunting o Limited resources § More resources necessary § more competition over resources § more conspicuousness to prey § more territory for nesting sites, food, water, etc. • Social interaction o Access to mates o Assistance in child-‐rearing o More learning opportunities o Information sharing o Cooperation/coalitions o Presence of males = protection form predators o Costs: social conflicts and disea se § High risk of disease § Social conflicts § Competition for mates § Aggression § Presence of males = infanticide • Infanticide = highest cause of infant mortality in mountain gorillas Phylogeny (a hypothesis of evolutionary relationships) vs. taxonomy (the classifi cation system used) o Phylogeny = hypothesis because information is always changing o Taxonomy = best when reflects phylogeny Catastrophism (one or more disasters created features on the earth in a short time) vs. Uniformitarianism (geological processes acting today were acting in the past; the earth is ancient) o Catastrophism: relatives in different climates experienced biological changes due to new environments o Extinction as evidence for catastrophic disasters that wiped out past life forms; new creations/migrations replaced them o No framework for mechanism of change o American degeneracy (WRONG) § Animals in the Americas degenerate into lesser forms o Uniformitarianism: geological processes are uniform over time; slow, gradual changes suggest ancient age of Earth o Lyell’s Principles of Geology: major evolutionary influence Typology and essentialism (the Greeks) vs. population thinking (i.e., emphasis on variation – Darwin) • Plato and Aristotle’s essentialism o Early attempt at understanding and ordering the natural world § The eidos (idea or type) is the only thing that is fixed and real o Gaps in nature are real and represent discontinuities between types § Immutability of species: an unalterable fixity of essence • Typological thinking and the great chain of being o Scala naturae: the great chain of being § Life arranged in orderly, hierarchical order § Humans at the top, various groups below: • Beasts (mammals) • Birds • Fish • Reptiles • Insects • Plants • Minerals • Carl von Linne, Systema Naturae (book) o Orders primates; first time humans are with mammalian order § Humans in Hominidae; great apes in Pongidae § Binomial nomenclature; genus and species Inheritance of acquired characteristics (Lamarck) vs. natural selection (Darwin) and particulate inheritance (aka Genetics – Mendel) • Jean-‐Baptiste Lamarck o Change in individual’s lifetime through use or disuse o Acquired or lost traits are passed to next WRONGneration = § Ex: giraffes with longer necks • Evolution by natural selection: o Lamarck’s theory: variation is acquired o Darwin’s theory: variation is inherit ed o Variation is the key o Differential survival and reproduction • Gregor Mendel o Demonstrated particulate inheritance: the concept of heredity based on transmission of genes § Common garden peas—dichotomous variation; independent traits are bred true—produce strains of plants that resembled their parents’ generation after generation Homology (a trait shared from common descent) vs. Homoplasy (conve rgent or independent evolution) • Homology: similarity of traits resulting from shared ancestry, a result of descent wi th modification o Ex: humans are similar to birds o Different from each other but with similar base • Convergence (analogy, homoplasy); appearance of similar traits due to similar use, not common ancestry o Wings in insects, birds, bats o Warm-‐bloodedness (endotherm y) in birds and mammals o In contrast to homology “Ontogeny” does not “recapitulate phylogeny” – development proceeds from general to specific • Ernst Haeckel (1834-‐1919) o Ontogeny recapitulates phylogeny: independent development retraces the evolutionary history of a species (ex: fish, amphibian stages) o Ontogeny: growth and development § Ex: see embryo pass through different evolutionary stages = WRONG • Karl Ernst von Baer (1792-‐1876) o Primary germ layers; all organism made with same tissues o Von Baer’s law of development proceeds from general to specific Steroid hormones: androgens, estrogens, gonad and genital formation, secondary sexual characteristics Steroid hormones • Gonads (ovaries or testes) create androgens • Androgens can then be converted into estrogens • Estrogens and androgens are present in males and females at different concentrations • Androgen o Converted from progestin in gonads o Testosterone in primary androgen o Necessary for penis formation and spermatogenesis (sperm creation) o Influence male secondary sexual characteristics—pattern and density of body hair; comb size in roosters; antler growth in deer, etc. o Behavior effects—mating, aggression, etc. • Estrogen o Converted from androgen in gonads o If excess androgens are produced and not immediately converted to estrogen, they can affect female physiology and behavior o Influence genital tract formation (ex: uterus size) o Influence female secondary sexual characteristics (ex: breasts) o Influence sexual behavior and maternal aggression Why chromosomes don’t necessarily determine sex (and certainly not sexuality or gender). Think androgen insensitivity, adrenal hyperplasia, and XO, XXY, and other nondisjunction errors • Complete androgen insensitivity syndrome o XY but inability to respond to androgen o Manifests in undescende d testicles and “feminized” genitalia o Intersex • Congenital adrenal hyperplasia o XX with oversized, overactive adrenal glands o Can result in male sexual characteristics (external genitalia, facial hair, etc.) • 5-‐alpha-‐reductase deficiency (testes descend at age 12) • sex-‐chromosome variants: o XO (Turner’s syndrome): only 1 sex chromosome o XXY (Kleinfelter’s syndrome): trisomy of sex chromosomes o XYY Adaptive radiation and island biogeography – e.g., Galapagos tortoises and finches • Adaptive radiation: diversification from one founding species into man species occupying different niches o Galapagos Finches: § Beak differences • Cactus finch: long beak • Ground finch; short beak • Tree finch: parrot-‐shaped beak for stripping o Galapagos tortoises § Giant tortoises vary in shell shap es • Dome-‐shaped on lush islands • Saddle-‐shaped on arid islands Artificial selection as a special type of natural selection in which humans select wh ich plants or animals reproduce • Artificial selection: process by which humans select which member of a species reproduce o Farmers select for certain features in plants (seeds, stems, leaves, fruit) o Animal breeders select for woolier coats, milk or meat production, etc. • Natural selection but humans are doing it Preformationism vs. blending inheritance vs. epigenesis t (formation of a zygote – fertilized egg) • Preformationism: WRONG o Tiny version of fully formed individual in sex cells (homunculus) o Problems: 1. Infinite homunculi 2. Hybrid domestic animals o Eventually replaced by the concept of epigenesist: an organism develops from a fertilized egg • Darwin’s blending inheritance: uniform blend or parents’ phenotypes (outward appearance) are passed on to offspring o Problem: fitness effects of 1 parent would be blended out by the other parent; this diminishment continues with offs pring o Variation can’t be maintained in this way DNA replication, transcription, translation, prot ein synthesis, mitosis, meiosis • DNA replication o Occurs during cell division o Enzyme separates bonds—DNA is “unzipped” o Assembly of complementary nucleotides o 1 parent DNA strand into 2 daughter strands • Protein synthesis: assembly of proteins from amino acids, which occur at ribosomes in cytoplasm via mRNA A. Transciption (in nucleus) 1. DNA unzips 2. RNA strand forms and copies DNA 3. mRNA leaves nucleus and goes to ribosome B. Translation (in ribosome) 1. mRNA binds to ribosome 2. ribosome reads codon 1 by 1 3. tRNA brings coded for amino acid for each codon a. Protein chain formed • Mitosis: somatic cell division that results in formation of 2ls; 1 diploid cell to 2 diploid cells • Meiosis: sex cell division in testes and ovaries; results in genetically distinct gametes; 1 diploid cell to 4 haploid cells http://www2.le.ac.uk/departments/genetics/vgec/diagrams/109 -‐mitosis_meiosis.gif • Locus: location of a gene on chromosome • Allele: variant form of a gene o Homozygous: same allele at both loci of gene o Heterozygous: 2 different alleles at loci of gene • Dominant: allele always expressed when present • Recessive: masked allele when dominant allele is pres ent • Codominant: the alleles are co-‐expressed; neither is dominant o Ex: ABO blood system • Punnett square https://passel.unl.edu/Image/NolanDiane1129928529/Punnet1.JPG Forces of evolution • Gene flow: exchange of genetic material between populations (admixtu re) o Migration with reproduction o High genetic relatedness between populations o Introduce new genotypes and phenotypes to populations o High variation within, low variation between § Populations within a species (generally) • Mutation: errors during DNA replication = random alterations in DNA sequence o Mutations in non -‐coding regions are neutral o Mutations in coding regions are neutral or good/bad o Mutations in gametes are passed on o Ultimate source of novel genetic variation NO MUTATION = NO VARIATION = NO EVOLUTION • Genetic drift: random changes in gene frequencies in population due to random sampling; neutral theory o Effect inversely proportional to population size; strongest in small population o Effect often greater over longer time periods o Random: no directionality o Fixation or disappearance of alleles § Can’t affect population quickly o Ex: Bottleneck: dramatic drop in population size § Results in low genetic variation § Long, slow process of mutation accumulation to rebuild genetic diversity § Disease threat (anti-‐disease resistance) o Ex: Founder effect: new populations that become isolated from their parent populati on and carry a subset of genetic variation • Natural selection: differential survival and reproduction o Acts on phenotype, not genotype o Directional selection: selection against 1 extreme o Stabilizing selection: selection against both extremes (or average) • Genetic drift and natural selection o Drift: strongest in small populations over long time periods o Selection: can be strong in large populations over short time periods § Ex: stabilizing selection: 7 vertebrae in mammals Darwin’s theory of evolution + Mendel’s theory of inheritance = Evolutionary synthesis
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