week2-2.darwin.evolution.microbio

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Anthropology

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Oct 30, 2023

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8/27/23 1 DARWIN & EVOLUTION Dr. Derek Boyd Anth 1100: Biological Anthropology Fall 2023 1 WHY DOES HISTORY MATTER? Scientific discoveries do not emerge in a vacuum! Discoveries in astronomy and geology impacted biology by changing how we see the universe Not a ladder (old ideas not necessarily wrong or stupid) The scientist a product of their own time 2 EARLY UNDERSTANDING OF THE WORLD Anthropocentric universe Static earth history How the Universe is explained: § Creator designed the universe § Creations are perfect—fixity of species - Variation = Imperfections Goal was to understand all of Creation to get closer to God 3

8/27/23 2 OLD IDEAS FROM THE GREEKS Fixed forms Type and Essence Hierarchical variation § Variation within types were unexplained Aristotle’s Great Chain of Being Aristotle (right): 385-322 BCE ‘Scala Naturae’ 4 OBSTACLES TO EVOLUTION Fixity of Species § No change = No evolution Young Earth § No time for evolution to take place 5 THE RENAISSANCE Late 1400s to its peak in the late 1700s The birth of: § Modern philosophies § Arts § Sciences Separation of science and religion 6

8/27/23 3 NICOLAUS COPERNICUS (1473-1543) Polish mathematician and astronomer First intellectual upheaval in Western world Heliocentric theory § Undermines Anthropocentric universe 7 ISAAC NEWTON (1643-1727) English physicist/mathematician Principia (1687) introduces modern era of physics Theory of Universal Gravitation Mechanistic universe § A move towards natural laws 8 CHANGED VIEW OF THE UNIVERSE Anthropocentric à Heliocentric § God’s Creation no longer the center of the universe Mechanistic = natural laws can explain and even predict phenomena in the cosmos and on Earth Facilitated the separation of religion and science § Religion is no longer the sole source of knowledge 9

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8/27/23 4 JAMES HUTTON (1726-1797) Scottish geologist, naturalist Theory of the Earth (1795) Earth transformed by slow processes § Erosion § Deposition § Uplift Establishes deep time because slow processes require time Modern rock cycle, informed by Hutton & Lyell 10 CHARLES LYELL (1797-1885) Scottish Geologist who wrote Principles of Geology (1830-33) Promoted deep time alongside Hutton Undermined supernatural catastrophes as explanation Uniformitarianism § Slow geological processes produce continuous changes to earth’s surface § No need for supernatural catastrophes 11 CHANGED VIEW OF EARTH Young Earth model à Deep Time Static earth history à Dynamic earth history Catastrophism à Uniformitarianism Quote by Hutton à 12

8/27/23 5 CAROLUS LINNAEUS (1707-1778) Swedish botanist Systema Naturae (1735) Formalized classification system § Binomial Nomenclature - e.g., Canis familiaris (Genus species) § Humans included (multiple origins) 13 GEORGES CUVIER (1769-1832) French comparative anatomist & catastrophist Fixity of Species Function is more important than form for taxonomy § similarities between species could only come from similar function 14 ÉTIENNE GEOFFROY SAINT-HILAIRE (1772-1844) French anatomist Philosophie Anatomique (1818) § Organisms can be modifications of a single type Idea that became Homology § Structures in different organisms can be modifications of a type § Parts change in shape/size but remain connected in the same pattern 15

8/27/23 6 GEORGES-LOUIS LECLERC, COMTE DE BUFFON (1707-1788) French naturalist Histoire Naturelle (1749) § Questioned Fixity of Species § Recognized Environment-Species interaction § Climate change as agent of species alteration § But no mechanism proposed 16 JEAN-BAPTISTE LAMARCK (1744-1829) French naturalist Followed Buffon and others in thinking that life is not fixed Offered first mechanism for evolution! Philosophie Zoologique (1809) § Theory: ‘Inheritance of Acquired Characteristics’ 17 THEORY OF THE INHERITANCE OF ACQUIRED CHARACTERISTICS New Generation enters the environment These alterations are passed down to offspring ‘Life’ fluids and forces concentrated in used body parts, leave unused parts Body part responds to the changes in ‘life’ fluids, reshaping itself Changes in environment Changes in Animals’ activity/behavior Increase/Decrease in Use of certain body parts 18

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8/27/23 7 ACQUIRED CHARACTERISTICS Activity can change anatomy. Change is inherited. Unit of change and selection = INDIVIDUAL No “struggle” for existence Directional Evolution: Organisms were driven by nature to be become more complex 19 CRITICS OF LAMARCK Lack of explanation for how acquired traits could be inherited Lack of observations of ‘vital forces’ Lack of experimental support …But no alternative mechanisms available 20 PARTING VIDEO This is what can happen when you take your personal observations as fact without using the scientific method… https://www.youtube.com/shorts/9qSQ5khOqXY 21

8/27/23 8 DARWIN & EVOLUTION Dr. Derek Boyd Anth 1100: Biological Anthropology Fall 2023 22 CHARLES DARWIN (1809-1882) English intellectual Med school dropout, Divinity Degree from Cambridge Also studied botany, geology Familiar with work of Lamarck, Cuvier, and Lyell Prior to trip on The HMS Beagle, accepted Fixity of Species 23 HMS BEAGLE (1831-1836) Selected to be the ship’s ‘naturalist’ Observations eventually shaped his theory Sailed Dec. 1831 – Oct. 1836 (5+ years !) Made key stops in: South America, Galápagos Islands, New Zealand, Australia & South Africa 24

8/27/23 9 GALÁPAGOS FINCHES Observed variations in similar-looking finches Hypothesis (1845): “One might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.” Common descent? 25 THOMAS MALTHUS (1766-1834) English economist An Essay on the Principle of Population (1798) Competition: “struggle for existence” 26 THEORY IN THE WORKS By 1844, Darwin had formulated and written up Theory of Natural Selection But does not publish until 1859 Why? § More data wanted § Controversy 27

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8/27/23 10 ALFRED RUSSEL WALLACE (1823-1913) Scottish naturalist Also integrated Malthus, led him to conceive of natural selection independently of Darwin Wrote to Darwin Read to the Linnean Society of London 28 ON THE ORIGINS OF SPECIES The Essential Ingredients for Natural Selection : 1. variation 2. mortality (differential reproductive success) 3. heredity The Additional Requirement for Evolution of Species: 1. deep time Non-random difference in reproductive success among individuals from generation to generation 29 LAMARCK VS. DARWIN/WALLACE Use/Disuse Vital fluids and forces Inheritance of acquired traits Individual evolves No extinction Increasing complexity Variation Differential survival Inheritance of trait already present Population evolves Extinctions Not directional 30

8/27/23 11 NATURAL SELECTION HIGHLIGHTS Natural Selection is a mechanism of evolution Natural selection is a non -random process leading to evolution. Natural selection acts on the individual , evolution acts on the population A mechanism that can explain emergence of new species. § Fixed Species vs. Biological Continuity Darwin’s idea of life as a branching tree from his notebook 31 DARWIN’S MISSING PUZZLE PIECE How does heredity work? Observed that sexual reproduction increases variation but how? What is the source of variation? ‘Blending’ inheritance? § Would actually decrease variation No knowledge of ‘gene’ 32 KNOWLEDGE CHECK PollEv.com/dab844 33

8/27/23 12 PARTING VIDEO https://www.youtube.com/watch?v=rFxu7NEoKC8 34 GENETIC INHERITANCE Dr. Derek Boyd Anth 1100: Biological Anthropology Fall 2023 35 GREGOR MENDEL (1822-1884) Monk in today’s Czech Republic Studied botany at University of Vienna Performed experiments on pea plants to discover laws of inheritance, published 1866* § How are traits expressed in plant hybrids, i.e., offspring of very different looking parents? * Note : The sixth (final) edition of Charles Darwin's The Origin of Species was published in 1872 36

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8/27/23 13 MENDEL’S WORK Traits he studied 37 3: F1 plant self-fertilized to produce short and tall offspring (F2), with 1:3 ratio of short to tall MENDEL’S WORK Does a tall parent and a short parent produce offspring intermediate in height? 1 2 3 1: Pure tall bred with pure short 2: All tall offspring (F1) Short plant reappears 38 MENDEL’S WORK Mendel developed a model – F1 parents consistently generated offspring in these 1:3 trait ratios He noticed that crossing the short F2 plants consistently produced short offspring Crossing the tall F2 plants varied in their ratio of offspring 39

8/27/23 14 MENDEL’S PRINCIPLE OF SEGREGATION Observations from crosses led to these inferences: § Different expressions of a trait were controlled by discrete units § One unit inherited from each parent. Units united during fertilization. - Principle of Segregation : Units separate during gamete formation 40 MENDEL’S PRINCIPLE OF DOMINANCE/RECESSIVENESS Unit for shortness in F1 did not just disappear § Present but not expressed Dominant : A trait controlled by one unit that is expressed regardless of the presence of the other unit. Recessive : A trait controlled by one unit that is NOT expressed in the presence of another (dominant) unit. 41 GENES AND EXPRESSIONS Genotype : § The genetic make up of an individual. § Refers to an organism’s entire genetic makeup Phenotype : § The physical characteristics of an organism. § The detectable expressions of genotypes. § Can be influenced by environmental factors 42

8/27/23 15 PUNNETT SQUARE Homozygous Dominant Heterozygous Heterozygous Homozygous Recessive GENOTYPE PHENOTYPE Note how the same phenotype can arise from different genotypes. 43 MENDEL’S PRINCIPLE OF INDEPENDENT ASSORTMENT Are different traits always inherited together? 1 2 3 F2 generation showed two new combinations not seen in parents: Tall-Green, Short-Yellow Principle of Independent Assortment : the distribution of one pair of units into gametes does not influence another pair 44 MENDELIAN INHERITANCE Complete dominance : only one unit is expressed in heterozygote Codominance : both units are expressed completely and simultaneously in heterozygote Incomplete dominance : traits of parents appear “blended” in the heterozygous offspring—a partial expression unlike a complete expression in a homozygous individual 45

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8/27/23 16 GENETIC MATERIAL Resides in cells Nuclear and mitochondrial 46 DNA Deoxyribonucleic Acid (DNA) - known by 1869 but function was not understood. 1953: Molecular structure discovered. DNA’s role in heredity is established. Double helix composed of sugar-phosphate chain. “Rungs” formed by joined base pairs. “ Nucleotide ” = sugar + phosphate + base 47 DNA STRUCTURE Specific pairing of bases: § Adenine (A) – Thymine (T) § Guanine (G) – Cytosine (C) Which means strands are complementary… Which allows for self-replication Base pair sequence = Genotype 48

8/27/23 17 DNA CAPABILITIES Make proteins. § Proteins build us and make things happen! § structural: hemoglobin, collagen § regulatory: enzymes Direct the development of the organism Hereditary due to ability to self-replicate § makes copies of itself that can be passed on to future generations. Hemoglobin protein molecule resides in red blood cell and carries oxygen. 49 DNA REPLICATION Enzymes unzip double-helix Bases are attracted to their match on each template strand 50 GENES From DNA to protein… Short strand of DNA that codes for the manufacture of a protein § Sequence of bases (A,T,G,C), called a gene Codons - triplet nucleotide sequences –– code for specific amino acids. Long sequences of amino acids form proteins 51

8/27/23 18 BASIC DNA TERMS Genome : the entire set of DNA of an organism § Contained in chromosomes § Chromosomes are paired (homologous): carry genetic information influencing the same trait From Mom From Dad Sex Chromosomes 52 BASIC DNA TERMS Locus : the location of the gene in the genome § Its “address”: which chromosome, where on the chromosome Gene “X” on Chromosome 10 53 Allele : alternate form of a gene at the same locus on paired (homologous) chromosomes From Mom From Dad BASIC DNA TERMS 54

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8/27/23 19 CHROMOSOMES Each human somatic cell has 46 chromosomes (=23 pairs) § 46 is the diploid number § 22 pairs of autosomes + 1 pair of sex chromosomes Each sex cell (egg or sperm) has 23 chromosomes § 23 is the haploid number 23 + 23 = 46 55 PARTING VIDEO https://www.youtube.com/watch?v=lU_heZEnAi4 56 GENETIC INHERITANCE Dr. Derek Boyd Anth 1100: Biological Anthropology Fall 2023 57

8/27/23 20 CELL DIVISION PROCESSES Make new somatic cells § Growth + Development § Repair § Maintenance End product is diploid § two complete sets of chromosomes Make sex cells, or gametes (egg, sperm) § Sexual reproduction End product is haploid § half the usual number of chromosomes Mitosis Meiosis 58 CELL DIVISION PROCESSES Mitosis Meiosis 59 MEIOSIS - RECOMBINATION Recombination can happen § Chromosomes literally exchange some genetic material Important source of genetic variation! 60

8/27/23 21 MEIOSIS Difference in net production between males and females Male: produce 4 sperm cells for every 1 cell Female: produce 1 egg + 3 ‘polar bodies’ for every cell § polar bodies ~ waste bins for excess DNA Important implications for reproduction strategies! 61 MENDELIAN TRAITS More than 21,000 human traits are inherited according to Mendelian principles § discrete traits § expression is relatively immune to environmental influence § controlled by alleles at one locus (i.e., by one gene) Foreign antigens provoke immune response Universal Donor: O blood type Universal Recipient: AB blood type 62 KNOWLEDGE CHECK PollEv.com/dab844 63

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