"Physical Anthropology- 101"
Physical Anthropology- 101 ****************************** M. Leonor Monreal Fullerton College ****************************** Notes & Assignments 1 Physical Anthropology Questions By K. Markley Are the following statements true or false? Write an F or T next to each question (you will NOT be graded on this exercise). 1. Science can be used to explore any question that humans have. At this time there is enough evidence for scientists to state absolutely that UFO’s do not exist. 2. The age of the earth is some 4.5 million years old. 3. Charles Darwin’s theory of natural selection has undergone so many revisions and changes since he first put it forth in 1859 that he would hardly recognize it today. 4. Fittness, in Darwinian terms, refers only to differential reproductive success. The most “fit” individuals are those who produce more offspring than others within their group. It does not necessarily have anything to do with size, strength or intelligence. 5. All life on earth is made up of the same DNA bases, adenine, guanine, thymine and cytosine. In general, it is the sequencing and number of each base in a sequence that codes for all of the different life forms on earth including bacteria, flowers, trees, dogs, and humans. 6. Females are more likely than males to be red-green colorblind. 7. The completion of the Human Genome Project has shown that aggression is a genetic trait coded for in human genes. 8. Orangutan’s are monkeys. 9. Humans are unique in both their physical and behavioral features as compared to other primates. 10. Baboons, an old world monkey, have been shown to make “friends” with each other and to form alliances, just like humans 11. All scientists agree that there are only two sexes in the species Homo sapiens. 12. Racial categories of humans are social constructs. There is no way to definitively divide humans into biological races. 13. Human’s co-existed with dinosaurs (cartoons don’t lie!) 14 Neanderthals co-existed and interbred with early modern Homo sapiens 15. The oldest “human-like ancestors” in the fossil record are some 4.5 million years and they are considered “human-like” because of their big brains. 16. Forensic anthropologists can determine the lifestyle, sex, and approximate age an individual was when they died by examining skeletal remains. 17. All Christian theologians and churches state that you cannot accept evolutionary theory and still be a good christian. 18. In Europe there is not, for the most part, a creation/evolution debate. This debate is primarily an American phenomena. 19. Evolutionary theory can explain the origin of life on earth. 20. Evolution is only a theory (and therefore not a fact). 2 M. Leonor Monreal Physical Anthropology 101 KEYTERMS Natural Selection: defined as a “process of evolutionary change based on differential reproductive success (fitness) of individuals w/in a species” Key components of natural selection: Variation: variation exists in all individuals, individual’s traits vary within populations – for instance individuals vary in their size, ability to resist disease, their color, etc. Competition: exists between individuals within a population for survival. Competition exists between individuals over access to food, the ability to avoid predators, ability to evade disease, etc. Environment or nature “selects” desirable traits: we know an individual has been “selected” if they are more successful reproductively. Differential reproductive success is the basis by which individuals “fitness” is measured. Fitness: Fittest individuals produce highest number of offspring, differential reproductive success Inheritance: Traits are inherited by offspring Environments change: therefore the traits that are positive or selected for today may not be positive or selected for in another environment. Natural selection results in: populations changing over time- as individuals within the populations change. Over enough time new species will form- speciation As regards Natural Selection, keep in mind: Selection operates at the individual level- selection of individuals based on the traits that they possess Populations evolve- not individuals. It is populations that change over time as individuals with the most advantageous traits are “selected” and produce offspring that have their traits. Natural Selection is not progressive- it doesn’t lead to more perfect organisms, it selects for traits that are “positive” in a particular environment, in relation to reproductive success, it does not have any particular direction or teleology Natural Selection is not foolproof- extinction is the norm o Variation must be present to be selected o There must be time for selection to occur- if environmental change is too sudden or too drastic it won’t work 3 M. Leonor Monreal Physical Anthropology 101 By K. Markley This is a general outline of what you need to know for the section on genetics. To make the best use of this information, read your text, attend class and take notes and then use this as an outline for key concepts and understandings. Genetics: study how traits are transmitted from one generation to the next. The study of genetics informs us as to where variation comes from and how inheritance works. The genetic code, carried by DNA, is basically a set of instructions for the production (or synthesis) of proteins from amino acids. Cells: The basic unit of life in all living organisms is the cell. Humans start life as a single cell. An adult human being is comprised of some 1,000 billion cells. Cell division and replication of the somatic cells is responsible for our growth as a human being. There are two basic types of cells that we are concerned with in this class. o Somatic cells, which comprise the body tissue, muscle, bone, skin, nerves, etc. that make up our body. Each of our somatic cells contains all 23 pairs of our chromosomes. o The sex cells or gametes are the cells of reproduction (eggs and sperm). The sex cells contain only half of our chromosomes DNA resides in the nucleus of the cell, carries the genetic code and directs cellular functions. DNA is the genetic material of all life on earth. Structure of DNA is a double helix or twisted ladder. The sides of the ladder are made up of sugar and phosphate units and the rungs of ladder composed of the four nucleic acids; o cytosine-C, guanine-G, adenine-A, and thymine-T. o The four nucleic acids combine in a very specific way, A only with T and C only with G. o This is the key for the ability of DNA to direct cell division, cell replication and protein synthesis. o All life on earth is made up of these four DNA bases. Cell division and replication: during this process enzymes split the rungs of the “ladder” in half. The helix unwinds and the exposed bases of the ladder rungs attract the appropriate complementary bases. Thus an exact copy of the cell is produced. Mitosis: cell division of somatic cells, produces 2 exact daughter cells. This is an ongoing process in the body. Mitosis works for repair and growth (nails, hair, bone marrow, etc. constantly replicating). Each somatic cell (if there is no problem or error in the replication) contains all 23 pairs of an individuals chromosomes. Meiosis: cell division where sex cells are produced (gametes; sperm & eggs). During meiosis the cells undergo an extra round of division. The result is that the sex cells contain only 23 chromosomes. The number of chromosomes are halved during meiosis. Genetic diversity (variation) is enhanced thru meiosis. In the production of each gamete or sex cell there is a 50/50 chance as to which one of their pair of chromosomes they pass onto to their offspring. Meiosis is a powerful source to reshuffle the existing variation in the parental generation. Each human has some 8 million possible combinations of their chromosomes for their offspring thru meiosis. 4 M. Leonor Monreal Physical Anthropology 101 Protein Synthesis: is the process by which the genetic code puts together proteins in the cell. For this process DNA “splits” and attracts mRNA (in RNA uracil replaces thymine), mRNA completes the production of proteins in the ribosomes where the “message” is decoded. tRNA reads the “message” to produce amino acids and then proteins. Proteins, in large part, make up what we are (bone, muscle, hemoglobin, enzymes, etc.). Protein synthesis is the assembly of chains of amino acids (codons) into functional proteins. This process is directed by DNA, using RNA. Think of the DNA bases as being the letters of an alphabet and there are only 4 letters (A, T, C, and G). Each word in the DNA alphabet is only 3 letters (these “words” are called codons). There are only 20 possible words formed with the 4 letters (the 20 amino acids are the 20 words). The “words” or amino acids combine in various sequences and quantities to form the hundreds of thousands of proteins that make up a human being. Feature Analogue Meaning Base (A, T, C, G) letter Codon word amino acid gene sentence protein Genes are portions of the DNA molecule that code for specific traits (proteins, or portions of a protein). Humans have some 30,000+ genes. These genes code for hundreds of thousands of proteins. Each gene resides at a specific location on a chromosome (locus) and each individual receives two “genes” or alleles at each location, one from each parent. Locus- Genes unique location on chromosome Alleles-alternative forms of gene- there are always two alleles at each locus Genotype: alleles possessed by organism Phenotype: physical expression of alleles Homozygous: having two of same allele Heterozygous: having two different alleles Alleles come in various forms and this impacts their expression in the individual Dominant: allele expressed phenotypically Recessive: allele not expressed unless both alleles are recessive co-dominance: expression of both alleles in an organism (the ABO blood system is an example with A and B being co-dominate in their expression) incomplete dominance: occurs when a recessive allele does have some phenotypic effect, the recessive allele is not completely “masked” by the dominant allele (tay sachs is an example) Example: one trait that all “normal” humans have is earlobes, which come in two different forms, either “free hanging” or “attached.” If your earlobes are “free hanging” then the base of your earlobe is not attached to your neck, if your earlobe is “attached” then the base of your earlobe is attached to the base of your neck. The trait is coded for by one gene. Either alternative for the trait- either free hanging or attached is dictated by an allele. The allele for free hanging is recessive. Therefore an individual who has two recessive alleles (ee) is free hanging. An individual who has one of each allele (Ee) is attached and an individual who has two dominant alleles (EE) is also attached. 5 M. Leonor Monreal Physical Anthropology 101 Alleles: Each individual has only two alleles at each locus (inheriting one allele from each parent). Even though there are only two alleles at each locus, depending on the trait there may be anywhere from only two alleles possible for a trait (ear lobes), three alleles possible (A, B, O blood system) to thousands of alleles (HLA system works to reject foreign tissue). Keep in mind at each locus we only have two alleles. Traits can be determined by one or more genes and can be impacted by the environment monogenic traits: one gene, one effect (hitchhikers thumb) polygenic traits: two or more genes for one effect, often influenced by environment (skin color) pleiotropy: single gene for multiple traits (albinism) Human traits can be both polygenic and pleiotropic. Chromosomes are strands of DNA in the nucleus of the cell which contain the genetic info for inheritance. Each species has a specific number of chromosomes. All “normal” humans have 23 pairs of chromosomes, 46 total (23 from each parent). Keep in mind that genes reside at specific locations on the chromosome. Autosomes are chromosomes 1-22 and they contain most all of the genetic info for our physical characteristics except sex determination. Sex Chromosomes: are X & Y. Females have two X chromosomes and thus have a matching pair for all of their chromosomes. The X chromosome is large and codes for some physical traits, some 300+ genes have been identified on the X chromosome. Males have an X & Y chromosome, therefore males do not have a matching pair for their sex chromosomes. The Y chromosome is small and for the most part codes for “maleness.” Since males do not have a matching pair of sex chromosomes this makes them more susceptible to traits that reside on the X chromosome. Principles of Inheritance Segregation: during meiosis chromosomes segregate (& therefore allele pairs segregate) o 50% chance for parent to pass on either chromosome (this is what is represented in the punnett squares, you are displaying the 50/50 chance for what the offspring will receive from their parents) Independent Assortment: genes on separate chromosomes are inherited independently, it is chromosomes that segregate during meiosis not individual genes Linkage: genes on same chromosome are inherited together, because it is chromosomes that segregate during meiosis Crossing Over: exception to linkage, during meiosis portions of chromosome pairs break off and cross over and are then recombined (recombination) Variation is increased through: Segregation, independent assortment, crossing over & recombination 6 Frequently Asked Questions- FAQ’S What is DNA? Deoxyribonucleic acid. It’s a molecule that controls the structure of proteins and is the primary carrier of genetic (hereditary) information. What is a Gene? There are many different ways to define a “gene.” For this course we will be using the term gene as a sequence of DNA that codes for a particular protein or regulates the expression of a protein What do Proteins have to do with Genes? Genes store the recipe for making proteins. We are basically made up of proteins and proteins do the work of the body: they generate energy, fight infection, digest food, form hair, etc. Each protein in the body is made from a gene by a translation of the genetic code (the DNA base sequences) What is a Genome? The complete set of genes carried by an individual. This analogy might help you better understand: the human genome is like a book which contains 23 chapters (chromosomes), and each chapter contains several thousand paragraphs (genes), each paragraph is made up of words (codons, amino acids), each word is written in letters (nucleic bases- adenine, thymine, cystosine, guanine) What is “junk DNA”? The majority of DNA does not code for proteins and until fairly recently it was thought that this DNA did nothing and so was labeled “junk.” Current research is showing that junk DNA does cause some impacts, it can work to minimize or increase the impact of a protein or trait. Characteristics of DNA Code Code is universal: the same triplet code (three bases that code for an amino acid) is present in all life on earth. o Humans share some 200 genes that they share with bacteria o Some 75% of our genes are shared with birds (we shared a common ancestor with birds some 310 million years ago) Code is triplet: each amino acid is specified by sequence of 3 bases Code is continuous w/out pauses: there is no separation from one amino acid (codon) to another, so if a base is deleted then entire frame is moved, drastically altering the “message” downstream for other successive codons o Change in one base is a “point mutation” o Code has “periods” to stop translation Code is redundant: there are 20 amino acids, and 4 DNA bases which makes for 64 possible triplets (w/3 stop messages), so there are 61 codons specifying 20 amino acids o Many amino acids coded for by more than one codon- (valine= UAA, UAG, UGA) o Redundancy helps if there is a change or mutation in the code it makes it less likely there will be drastic consequences 7 Things to keep in mind During meiosis parents pass on 50% of their chromosomal complement Punnett squares are used to calculate percentages for the possibility of what offspring will inherit with the union of parents chromosomes or gametes Offspring can express traits not expressed in parents (due to recessive alleles) Humans have pairs of all autosomes (22 from each parent, 44 total), females have a pair of sex chromosomes (two X’s, one from each parent), males have one X & one Y chromosome (males more likely to get conditions passed on X chromosome) Punnett Squares Work to show the possibilities for offspring. The outside of the punnett square reflects the alleles that the parents possess for a particular trait. It is a fifty-fifty possibility as to which allele each parent passes onto their offspring (through the process of meiosis). The inside of the square reflects the possibilities for their offspring. 8 Genetics Exercise: Protein Synthesis and Sickle-Cell Anemia Protein synthesis is the process by which the genetic code puts together proteins in the cell. DNA, residing in the nucleus of the cell contains the blueprint for each specific protein. The four letters or “bases” in the DNA “alphabet” (adenine-A, thymine-T, cytosine-C, and guanine-G) combine in various sequences and quantities to form “words” or codons. Codons are made up of three “letters” or bases (A, T, C, G) and they form amino acids. Each amino acid is made up of three letters. There are 20 different amino acids which combine in various sequences and quantities to formulate the hundreds of thousands of proteins that make up human beings. The genetic code is redundant in that each amino acid can be coded for in more than one way (e.g. lysine can be coded for by TTT or TTC). Hemoglobin is a protein made up of two chains of amino acids. There is a mutation that occasionally occurs in the second chain of hemoglobin. This mutation changes one of the bases (A, T, C, G) and results in the formation of an abnormal protein. Individuals that have this abnormal protein have a condition called sickle- cell anemia. Sickle-cell anemia results in the red blood cells becoming distorted and rigid (sickle shaped) and small clots are formed which deprive the cells of oxygen. Below are the first twelve amino acids that make up the second chain in the hemoglobin molecule. The mutation that causes sickle cell resides in this part of the protein. Below is the sequence of amino acids for normal hemoglobin (each amino acid is indicated by the first three letters of its name): VAL-HIS-LEU-THR-PRO-GLU-GLU-LYS-SER-ALA-VAL-THR Assume you are a researcher studying sickle-cell anemia. You have been given two unlabeled samples of DNA sequences. One is from a healthy individual, and one is from an individual with sickle-cell anemia. Using the table of amino acids (below) and the sequence of amino acids for normal hemoglobin (above), determine which strand is normal and which codes for the abnormal hemoglobin. (HINT: Remember that a codon is a series of three nucleotide bases that code for a particular amino acid). Leucine: AAT, AAC, GAG, GAC Proline: GGA, GGG, GGT, GGC Lyseine: TTT, TTC Serine: AGA, AGG, AGT, AGC Valine: CAT, CAG, CAA, CAC Histidine: GTA, GTG Alanine: CGG, CGA, CGG, CGT Glutamic Acid: CTT, CTC Threnine: TGA, TGG, TGT, TGC DNA Sequences 1. Individual A: C A T G T A A A T T G A G G A C T T C T T T T T A G A C G G C A T T G A Amino acids: _____________________________________________________________________ 2. Individual B: C A T G T A A A T T G A G G A C A T C T T T T T A G A C G G C A T T G A Amino acids: _____________________________________________________________________ 3. Who is the healthy individual? ______________ 4. Who has sickle-cell anemia? ________________ 5. How did you make this determination? 9 Natural Selection & Lamarck Scenario’s Read the following two scenario’s and determine which one describes Lamarck’s Hypothesis of Inheritance of Acquired Characteristics and which one describes Darwin’s Theory of Natural Selection. Match the key components listed below to each (either Lamarck’s hypothesis or Darwin’s theory) by putting the appropriate number next to the description. Scenario #1 Two species of birds exist on Daphne Major in the Galapagos Islands. The cactus finches, which live off of the cactus on the island and the medium ground finch which survives by eating the seeds on the island. The beaks of the finches are instrumental in their ability to get food. The size and shape of the finches beaks determines what seeds that are able to crack and eat. All of the medium ground finches are very similar in their beak size and shape. A drought hits the island and there is no rain for 550 days. Most all of the smaller seed that the medium ground finches eat are consumed and the medium ground finches start dying off. The only seeds left are quite large and hard. Some of the medium ground finches are able to change their beak size and adapt to the changing environment. These finches adapt their beaks to be able to crack the only seeds that are left in the environment, large, hard seeds. The finches that are able to adapt their beaks are able to survive the change in their food source and live to produce offspring. The offspring of the surviving finches are born with larger beaks that their parents evolved. The population of medium ground finches is now different, the population now has larger beaks and are able to eat larger and harder seeds. Scenario #2 Two species of birds exist on Daphne Major in the Galapagos Islands. The cactus finches, which live off of the cactus on the island and the medium ground finch which survives by eating the seeds on the island. The beaks of the finches are instrumental in their ability to get food. The size and shape of the finches beaks determines what seeds that are able to crack and eat. The medium ground finches are highly variable in their beak size and shape. A drought hits the island and there is no rain for 550 days. Many of the seeds that the medium ground finches eat are eaten up and the medium ground finches start dying off. The only seeds left are quite large and hard. The medium ground finches that have larger beaks are able to crack the larger, harder seeds. The finches with smaller beaks are not able to eat these larger, harder seeds and they die. The finches with the larger beaks are able to live and reproduce offspring. Their offspring inherit their parents larger beaks. The population of medium ground finches is now different, the population now has larger beaks and are able to eat larger and harder seeds. Components of Lamarcks hypothesis 1. Environments change 2. Individuals bodies change in response to environmental change 3. Variation is created within an individuals lifetime 4. Variation created within an individuals lifetime is inherited by their offspring Components of Darwin’s theory 1. Variation exists (in traits, among individuals within a species) 2. Competition exists 3. Environment selects desirable traits, as evidenced by fitness (differential reproductive success) 4. Traits are inherited by offspring 5. environments change 6. Populations evolve over time 10 History of Life on Earth Geological history is backdrop for life on earth, geological time scale divided into eras of biological & geological activity that stretch over long periods of time, use boundaries to mark periods of devastation or mass extinctions, eras subdivided into periods, w/in periods epochs MYA- BP Geological Era Periods Mass Extinctions Life Forms 4,600-2,500- Archean Precambrian 3 BYA geological tumult died down, unicellular (4.6 - 2.5 bya) organisms everywhere, some photosynthesis, starts changing atmosphere, adding oxygen Proterozoic Precambrian 1.4-1.9bya find eukaryotic cells, 1.2 bya multicellular life (red algae-Canada), Siberia 1 bya 3000- (3 bya) Paleozoic Precambrian Prior to 600-700mya record sparse, intense heat/pressure destroyed most remains 550 mya Cambrian 545mya mass Ancestors of all modern animal groups appear + extinction- meteor? formation of many now extinct species 505 Ordovician 440mya- mass Seas- algae, invertebrates, 1st vertebrates (jawless extinction fishes) 435 Silurian First land organisms, plants (had stems, no leaves, roots) & animals resembling scorpions 410 Devonian 370mya most fish, Age of fishes; invertebrates, fish w/bone, cartilage, invertebrates die off land mostly barren-scorpions, millipedes, invertebrates 360 Carboniferous Age of Amphibians: sea animals spending more time on land 1st 4 limbed animals- mixed adaptations for water & land-Acanthostega (fin on tail like fish, hips/legs/ toes, ribcage not strong enough to support internal organs out of water, but footprints showed brief land ventures, flat feet to move thru water w/8 toes) earth- insects, plants flourished on land, huge ferns, Coal Age (produced coal of today) 290 Permian 250mya-95% of Mass extinctions- 95% of terrestrial, sea organisms marine species reptiles gone- egg laying animals appear- extinct Cotylosaurs gave rise to dinosaurs, mammals, reptiles, birds 240 Mesozoic Triassic First mammals 205 Jurassic Dinosaurs everywhere 138 Cretaceous Flowering plants spread in diversity, triceratops flourished (cockroaches of cretaceous) 65 Cenozoic Paleocene Tertiary epoch Extinction of dinosaurs other marine life & mammals proliferate - diverse hoofed mamals, many marsupials, egg-laying monotremes 65mya- mass (ancestor to platypus), placental mammals appear, extinction event primate like animals appear 54 Eocene First primates- primitive prosimians 38 Oligocene Anthropoid evolution 25 Miocene Radiation of early apes 5 Pliocene First hominids, first members of genus Homo 1.65 Pleistocene Quaternary Evolution of genus Homo epoch .01 recent Humans develop agriculture, industry, explore space Stephen Gould perspective: With the appearance of each new type of animal we call it “The Age of Fish, The Age of Dinosaurs” and don’t discuss that many of the previous forms of life in existence continue to exist and often proliferate. For instance “the most salient feature of life has been the stability of its bacterial mode from the beginning of the fossil record until today and, with little doubt into all future time so long as the earth endures. This is truly the “age of bacteria” as it was in the beginning, is now and ever shall be.” Bacteria occupy a wider domain of environments and span a broader range of biochemistries than any other group. They are adaptable, indestructible, and astoundingly diverse. 11 Physical Anthropology-Hardy Weinberg Sample Problem L. Monreal 1. Evolution (definition): 2. Hardy-Weinberg Equilibrium Formula This formula is a tool researchers can use to document evolution occurring within a population. Researchers go into a population, select a trait for study and determine the genotype frequencies for that trait within the population. These “observed genotype frequencies” are then plugged into the Hardy- Weinberg formula (p2 + 2pq + q2=1) and the formula gives the “expected genotype frequencies” for this population under a hypothetical condition of no change. These “expected genotype frequencies” are hypothetical because populations are always being impacted to some degree by the processes of evolution. Comparison between the “observed” and “expected” genotype frequencies documents the change the population is undergoing and allows us to speculate as to what is going on in the population. 3. The Hardy Weinberg Equilibrium formula gives the expected genotype frequencies in a population in a hypothetical condition of no change. Why are these “expected” genotype frequencies of no change said to be hypothetical? 4. Steps to use the Hardy-Weinberg Equilibrium formula Determine the OBSERVED GENOTYPES for all individuals (3 options: homozygous dominant, heterozygous, homozygous recessive) Calculate the OBSERVED GENOTYPE FREQUENCIES for all individuals (divide the total for each genotype into the total number of individuals in the population for the three genotype frequencies) Calculate the total number of dominant alleles and the total number of recessive alleles for the population and then calculate the ALLELE FREQUENCIES for both the dominant and recessive alleles (dividing the total number of each type of allele into the total number of alleles for the population) Plug the allele frequencies into the Hardy-Weinberg formula. Use “p” to represent the dominant allele frequency and “q” to represent the recessive allele frequency. Hardy Weinberg Equilibrium formula: p² + 2(p)(q) + q² = 1 Your figures must add up to 1, to represent all possibilities. The resulting numbers will give you the EXPECTED GENOYPE FREQUENCIES p² = AA (homozygous dominant) 2 (p)(q) = Aa (heterozygous) q² = aa (homozygous recessive) Plug the EXPECTED GENOTYPE FREQUENCIES into your table and compare the expected genotype frequencies with the observed genotype frequencies. Remember the expected genotype frequencies are what you would expect to find if the population was not undergoing any change 5. What can the Hardy Weinberg Equilibrium model tells us? 6. For EACH process of evolution what information do we need to be able to speculate as to how allele frequencies can change over time (in relation to each process)? Mutation Gene Flow Gene Drift Natural Selection Sexual Selection 12 Sample problem: The Nacirema have a population of 98 individuals. They live in a secluded valley that is accessible only to travelers on foot. Visitors must hike for three days through rugged terrain to reach the Nacirema (they are rarely visited by anyone.) The Nacirema subsist by foraging for foods that grow naturally in the environment, hunting for small animals and diving for clams & shrimp (these are high status foods). Roving physical anthropologist Rosa Rodriguez and her research assistants are the first visitors the Nacirema have had in 3 years. Rosa examines the entire population to determine their genotypes for ear wax. As you recall ear wax comes in two forms, wet, brown, sticky and dry, gray and brittle, the dry ear wax is inherited as a recessive. Ear wax was chosen as a trait for study because the Nacirema really do not like the wet, sticky variety and they want to know what is going on with their population. The Nacirema find the wet, sticky earwax gross and it is hard to keep their kids ears clean. Rosa finds 27 individuals with dry ear wax and 36 individuals who are heterozygous for the trait and 35 individuals who are homozygous dominant. geno- number of observed expected total number total number type individuals genotype genotype of dominant of recessive frequencies frequencies alleles alleles EE Ee ee Total number of alleles= p = frequency of dominant alleles p= q = frequency of recessive alleles q= Expected genotype frequencies: p² + 2(p)(q) + q² = 1 Is change occurring in this population? What can we speculate as to what is happening in this population (you must list and address all of the five processes that can affect a change in allele frequencies over time)? 13 Hardy Weinberg Allele Frequencies should remain static unless there are processes that work to cause them to fluctuate. The Theory of Evolution has shown that the only processes that can work to change allele frequencies are: mutation, gene flow, gene drift, natural selection and sexual selection (an aspect of natural selection). So, if there are fluctuations in allele frequencies we must look to these processes to ascertain what is causing the fluctuations in allele frequencies. The Hardy Weinberg gives us a formula to see if change is going on in a population and to speculate which processes are interacting to change allele frequencies. The goal of using the Hardy Weinberg is to gain insight into how the processes of evolution work to change populations over time. Keep in mind we are only looking at one trait at a time. Mutation: “random change in the genetic code” it’s spontaneous & occurs at a regular rate o introduces variation to be selected for or against, rare for any given locus and can’t change allele frequencies more than 1% gene flow “random exchange of alleles between populations” introduces variation into populations but doesn’t change allele frequencies more than 1% o can be stopped: with geographic isolation or reproductive isolating mechanisms (or partially by cultural barriers in humans) gene drift “random fluctuation of alleles from one generation to the next” (punnett squares) o always occurring, can lead to big changes in allele frequencies in populations under 100 (sampling error, gamate sampling) o in large populations, sampling error is eliminated and there cannot be large changes in allele frequencies natural selection “selection based on differential reproductive success” can lead to big change allele frequencies o selection only occurs for traits that impact reproductive fitness, environment (niche) is a determining factor, how does the trait interact with fitness and with the niche of the organism? Can we speculate that the trait under study is impacting the ability of the individual to survive, to out-compete others in their population? sexual selection “selection of mates based on phenotypic traits” selection is always taking place based on phenotypic differences o sexual selection involves female choice (females generally invest much more into offspring than males, so they make their choice based on the health, genetic “superiority” of the male) and male competition (males access to females is regulated by other males, they compete with other males to get access to females) o how does the trait under study impact the organism phenotypically? To what degree would mate choice be impacted by this trait? To what degree would male competition be impacted by the trait? 14 Physical Anthropology – Hardy Weinberg Homework L. Monreal Hardy Weinberg Problems: These problems will be graded in class and are due on the date listed in your class schedule. You may handwrite the table for each problem (neatly, legibly) but you must type your answers For each of the following problems set up and fill in a Hardy Weinberg table and then answer the following questions for each problem: state whether change is occurring list each of the processes of evolution and then speculate (with EACH process) as to whether or not it could be working to change the allele frequencies in the population. State whether or not each process could be changing the allele frequencies either to a small or large degree and why you would speculate that the process of evolution can change the allele frequency. Sample problems- to be done in class Population under study: The Dorje are a community of 98 individuals living in a secluded commune in Nepal. They live in a harsh environment where cold, wind, rain, and snow are frequent and severe especially in the winter months. The Dorje survive by foraging for food and hunting for small game animals and so they spend a great deal of time outdoors. The trait under study is hairy nostrils (very hairy!). Hairy nostrils are a dominant condition. Genotype distribution: HH= 35, Hh= 36, hh= 27 Population under study: 923 coyotes. Trait under Study: color variation within this population called “mottled coloring.” This population of coyotes have learned to adapt to suburban conditions, often taking food left out for domestic pets. The coyotes traditionally have had a grayish brown coat color but lately quite a number of these coyotes have been observed with a mottled coat of various colors. This mottled coloring often makes it difficult to tell that the animal is a coyote. Mottled coloring has been determined to be a dominant trait. Genotype Distribution: MM= 200, Mm= 93, mm=630 Homework Problems 1. Population under study: 98 humans. Trait under study: sneezing fits in bright sunlight. The population is located on a small oasis on the edge of a large desert. The population faces frequent threats from roving bands of guerilla’s who will kidnap and/or kill the inhabitants if they find them. The people move frequently to keep themselves safe. They frequently trade goods with other populations of nomads like themselves. Sneezing fits in bright sunlight is a recessive trait. Genotype Distribution: SS= 35, Ss= 36, ss= 27 2. Population under study: 80 individuals who have agreed to take part in a multi-generational study to give insights into social group relations. These individuals are isolated in a self-contained environment for the duration of the study, which is expected to take 100 years. The population is responsible for growing their own food and periodically they have had significant problems with some crops. Brussel sprouts are one of the few vegetables that they have been able to grow consistently. Trait under study: ability to taste PTC. The individuals who have this trait find brussel sprouts to be very bitter tasting. The ability to taste is a dominant trait. Genotype distribution: TT= 20, Tt= 52, tt= 8 3. Population under study: 1158 humans. Trait under study: the large toe. This population resides in an isolated area of the Andes Mountains and survive by foraging for food, hunting small animals and maintaining small gardens. For several generations there have been a number of individuals born with an especially large, strong big toe. The individuals born with the extra large big toe are very adept at climbing steep walls to retrieve condor eggs for food (these eggs are highly valued for both food & status), however they have not been very good hunters or foragers. Having an extra large big toe is a dominant trait. Genotype distribution: TT= 255, Tt= 276, tt= 627 15 Physical Anthropology- Primate Report K. Markley The answers to the following questions must be typed. The due date for this assignment is in your class schedule. You may study with other students as you work to answer these questions. However, you must put the answers into your own words. The first two questions come from the Park text and class lecture, the rest of the questions come from articles in the Annual Editions text. 1. Define Socioecology and give one example of how it is used to analyze and predict primate behavior. 2. Define Sociobiology (all the components) and give one example of how it is used to analyze and predict primate behavior. 3. Machiavellian Monkeys: A) What is “tactical deception”? B) What role does the author’s research into primate deception play in our understanding of the evolution of the human brain? C) What are the three key things that the authors see as being connected to society? 4. What are friends for?: A) What are the assumptions as regards female and male behaviors in regards to mating in the “dominance hypothesis”? B) What is the question the author explores in this paper? C) What are the three ways in which the author’s findings (from nonhuman primates) challenge the popular scenarios for the evolution of female/male relationships? 5. Dim Forest, Bright Chimps: A) what are the differences in hunting, tool use, and food sharing between the Tai chimps and the Gombe chimps (be specific)? 6. Mothers’ & Others: A) what is “cooperative breeding,” and what does a species need to become “cooperative breeders,” B) Are humans “cooperative breeders”? C) What is the critical variable for infants to develop into “healthy” empathetic adults? 7. What’s Love Got to Do With It?: A) List three traits or adaptations that early humans shared with Bonobo’s, B) What is a key difference that the author notes now exists between bonobo’s and humans. 8. The Myth of the Coy Female: A) What is the author’s main point in the article? B) List three aspects of the author’s reasoning and data that is used to back up her opinion 16 Primate Studies: there are two major “theoretical” orientations used to explain and analyze primate behavior. Socioecology looks at the relationship between the environment and behavior. It is understood that animals interact with their environment and it impacts their behavior. The “environment” includes quantity and quality of food, predators, seasonal variation, etc. Intra- species differences (differences within species) can be explained in relationship to the environment. Sociobiology states that natural selection selects not only for physical traits but also for behavioral traits. Different behavioral traits are selected for in males and females because they have different strategies for reproductive fitness. See your text (Park text) for an outline of the key components of sociobiology and the different reproductive strategies for females and males. Primates: You need to know the 5 major groupings of non-human primates below and the key differences between them. You will also need to know key features of all of the great apes. 1. Prosimii: primitive primates, marginalized today, wet nose, often nocturnal, claw on one digit, scent glands (lemurs, lorises, tarsiers), more specialized than other primates 2. New World Monkeys: arboreal, prehensile tails, no estrus, little/no sexual dimorphism, dental formula: 2-1-3-3 (incisors, canine, pre-molars, molars), Mexico, central/south America 3. Old World Monkeys: more diverse environments, tropics to snow, more behavioral diversity, sexually dimorphic, females show estrus, arboreal & terrestrial, no prehensile tail, dental formula: 2-1-2-3 (same dental formula as both apes and humans). 4. Lesser Apes: gibbons, siamongs, Smaller body & brain size, Southeastern Asia, fruit eaters, brachiators, “monogamous”, territorial 5. Great Apes- the four groups below comprise the great apes Orangutans: Southeast Asia, Indonesia, arboreal, sexually dimorphic, males 200lbs, females 100lbs, solitary, primarily frugivores Gorillas: West Africa (forest areas), Central Africa (mountain area), sexually dimorphic, males 400lbs, females 200lbs, terrestrial, knuckle walkers, groups: one-male (silverback) multiple females,& offspring, vegetarians, shy Chimpanzee’s: equatorial Africa, mild sexual dimorphism, quadropedal knuckle walkers, varied diet (fruit, leaves, nuts, hunt for small mammals), partially arboreal, bonded males core of community, females show estrus, (fluid communities 50+) Bonobo’s: south Zaire only, physically leaner than chimps, more arboreal, varied diet, bonded females core of group, females continuous estrus Differences between monkeys & hominoids (apes & humans are classified as hominoids) Hominoids: physical differences compared to monkeys. Hominoids do not have a tail, generally have a larger body size, a larger relative & absolute brain size, a longer period of dependency & learning, a larger & stronger collar bone, a flexible shoulder joint and different limb lengths (monkeys limbs are all of the same general length). 17