Biological Anthropology Review

Chapter 1: Biological Anthropology

• The 4 fields of anthropology:
  • Cultural: study of human societies, especially cross-culturally
  • Archaeology: study of material culture of past peoples
    • Artifacts, material culture, salvage archaeology
    • Prehistoric, historic, and contemporary
  • Linguistic: study of language, history, and use
  • Biological anthropology: study of human biological evolution and biocultural variation (studying evolution relating to humans); physical anthropology
    • Paleoanthropology: fossil records of ancestral humans and primate kin
    • Skeletal biology and osteology: skeletons, patterns and processes of human growth, physiology, and development
    • Paleopathology and bioarchaeology: disease in ancient human populations, bones and nutrition
    • Forensic anthropology: human remains
    • Primatology: non-human primates and their anatomy, genetics, behavior, and ecology (some similarities to humans)
• Primates: our biological relatives; group of mammals with complex behavior, varied forms of locomotion
  • Lemurs, monkeys, apes
• Culture: learned behavior transmitted from person to person
• Language: set of written/spoken symbols used by humans to refer to things, makes transfer of knowledge to future generations possible
• Hominins: humans and humanlike ancestors (extinct bipedal relatives)
  • What makes them different?
    • ~6 mya: bipedalism (walking on 2 feet)
      • Darwin’s hypothesis: shift from life in trees to ground
      • Early hominins lived in woodlands (first arose in Africa), spent time in trees holding onto branches, moved limb to limb
      • Feet have longitudinal arch and non-opposable big toe (walking and running)
    • ~5.5 mya: loss of honing canine (originally for leafy diet, change in diet)
      • Reliance on tools for processing food
    • ~2.6 mya: material culture and stone tools (more complex and diverse than primates’)
    • ~<2 mya: speech (hyoid bone)
      • types of behavior engaged in (eg, burying dead and hunting in groups is complex enough for speech))
    • ~1 mya: hunting (utilizing tools for meat)
      • traveled long distances for prey
      • Human brain is bigger and more complex, requiring more protein(?)
    • ~10,000 ya: domestication of plants and animals
• Human genome: 20,000-25,000 genes (chromosomal and mitochondrial DNA) that represent all inheritable traits
• Scientific method:
  • Empirical data: based on observation and experiment
  • Theory: set of hypotheses rigorously tested/validated, leads to generally accepted explanation for specific phenomena
  • Scientific law: irrefutable truth of natural phenomena
    • Laws of gravity, thermodynamics and motion
    • Does not address why something takes place

Chapter 2: Evolution

• Species: group of closely related organisms having potential to interbreed/produce offspring
• Uniformitarianism: the natural processes of today are the same as those in the past (consistent, uniform, and slow)
  • Eg, water eroding, eruptions, natural disasters, creation of islands, asteroids
  • Hutton and Lyell (early 18th-late 19th centuries)
• Carolus Linnaeus: method of classifying plants and animals (binomial nomenclature)
  • Genus: can include one or more species
    • Eg, canis (genus) lupus (species)
  • Basis for taxonomy (organizing various elements)
• Catastrophism: natural disasters (eg, earthquake, volcanic eruption) are responsible for geological changes throughout Earth’s history, rather than evolutionary processes
  • Georges Cuvier (late 18th century)
  • This is false: catastrophic events are rare and did not explain the sequence of fossils Cuvier observed
• Lamarck(ism): evolution is marked by the inheritance of acquired characteristics
  • An organism can pass on features acquired during its lifetime to its offspring (ig, modifications in response to new demands/needs, like new organs)
  • Believed giraffes stretched to reach food at the tops of trees and thus their necks grew as a result, which they passed onto their offspring
  • This is false: offspring don’t inherit modifications by their parents because acquired traits don’t alter genes passed onto offspring; doesn’t explain how new traits arise in a species
• Thomas Malthus: argued for limits of human population growth rather than how species change
  • Argued that in nature, there is a tendency for animal populations to increase geometrically/indefinitely when availability of resources is relatively constant
  • Limits for populations to increase are controlled by availability of resources
  • Successfully compete for food = survive reproductive age
• Darwin’s observations (19th century):
  • Natural selection: organisms with specific features are able to adapt to their environment, survive and reproduce, increasing the frequency of the features in the population
    • Trait must be inherited, show variation between individuals, and environment must exert some pressure on it
    • Fitness: better at producing offspring
    • Population: mate in general vicinity (~25 miles)
  • Adaptive radiation: diversification of an ancestral group into new forms that are adapted to specific environmental niches (one lineage to many different species)
    • Eg, different finch variations (beaks adapted to different environments)
  • Gemmules: his units of inheritance, representative gemmules for body parts in reproductive organs
    • Blending inheritance: phenotype of an offspring is a uniform blend of parents’ phenotypes (false)
• Gregor Mendel: crossbred garden pea plants to observe certain characteristics over multiple generations
  • Mendelian inheritance: the transmission of genetic material/traits from parents to offspring
    • Law of Segregation: during gamete formation, the paired unit factors segregate randomly so each sex cell receives one or the other (equal likelihood)
      • Each parent only contributes one allele (half)
    • Law of Independent Assortment: during gamete formation, segregating pairs of unit factors assort independently of each other
  • Gene: basic unit of inheritance; a sequence of DNA on a chromosome
    • Chromosomes: made of DNA; contain hundreds or thousands of genes
  • Allele: one or more alternative forms of a gene; dominant or recessive
    • Genotype: genetic makeup of a trait made of 2 alleles (eg, GG, Gg, gg)
  • Phenotype: physical appearance of genes (eg, yellow or green)
  • Punnett square: used to predict possible genotypes and phenotypes of an offspring
• The 4 Forces of Evolution:
  • Mutation: primary cause for genetic diversity/new genes, can be advantageous or not
  • Natural selection: organisms with specific features are able to adapt to their environment, survive and reproduce, increasing the frequency of the features in the population
    • Eg, peppered moths (following Industrial Revolution, darker ones more common than peppered ones due to pollution camouflaging them)
  • Genetic drift: random change in frequency of different forms of a gene
    • Most drastic changes in small, relatively homogenous populations
    • Founder effect: when a small group (fewer than several hundred members) of a large parent population migrates to a new region and is reproductively isolated
      • Because it’s small, may not be representative of parent population’s genetic composition, thus gene pool diverges from parent
  • Gene flow: the diffusion/spread/exchange of new genetic material from one population to another
    • Decreases genetic variation between two populations as they become more similar and rare traits die out
• Areas of study that contributed to evolutionary theory:
  • Taxonomy: a system of organizing/classifying/naming past and modern life forms; reflects degree of relatedness (Linnaeus)
  • Systematics: classification of living organisms to determine their evolutionary relationships with one another
  • Evolutionary biology: process of change in organisms (Darwin)
  • Demography: population’s features; birth rate, death rate, size and density (Malthus)
  • Geology: Earth’s physical history
  • Paleontology: extinct life forms (fossils)

Chapter 3: Genetics and Genomes

• Prokaryotes: single-celled, no nuclear membranes/organelles, genetic material is a single strand in the cytoplasm, cell walls
  • Likely the first life on Earth (~3.5 billion ya)
• Eukaryotes: multi-celled, membrane-bound nucleus containing genetic material and specialized organelles
  • Cytoplasm: surrounds nucleus, suspends organelles
  • nDNA: chromosomal DNA in nucleus
    • Homoplasmic: identical in each cell type (except red blood cells) within an organism
  • Somatic cells: body cells; organs, tissues, etc.
    • Diploid: cell with full complement of paired chromosomes (46)
    • Mitosis: single cell copies nuclear DNA (replication), divides into 2 identical diploid daughter cells containing the same number of chromosomes as its parent
  • Gametes: sex cells; sperm in males, ova/eggs in females
    • Haploid: cell with a single set of unpaired chromosomes (23) (don’t contain all chromosomes from original parent cell)
    • Meiosis: one DNA replication and two cell (and nuclear) divisions, creating 4 haploid gametic cells (each with 23 chromosomes but no pairs)
      • Crossing-over: homologous chromosomes partially wrap around each other and exchange genetic information
      • Recombination: gene variants on maternal chromosome now on paternal and vice versa
  • Translocations: nonhomologous chromosomes exchange segments; relatively rare but can cause numerous diseases and infertility
    • Down syndrome: extra copy of chromosome 21 joins chromosome 14
  • Nondisjunctions: failure of chromosomes segregating, creating some gametes with abnormal numbers of chromosomes
    • Monosomy: a loss in number of chromosomes
    • Trisomy: a gain in number of chromosomes (Down syndrome)
  • Mitochondria: ATP/energy-producing organelles (use oxygen to turn food molecules (especially sugar and fat) into ATP)
    • mtDNA: mitochondrial DNA; 37 genes inherited from mother
      • Matriline: lineage/inheritance that can be traced from mother to offspring
      • Heteroplasmic: different/varying among different parts of a person’s body/among the same kinds of cells
  • DNA:
    • Made of nucleotides (sugar, a phosphate group, and one of four nitrogen bases)
      • 4 different nitrogen bases: A with T, G with C
      • A with U in RNA
    • Single nucleotide polymorphisms (SNPs): variations in DNA sequence due to the change of a single nitrogen base
      • Determine various attributes (eg, hair color and blood type)
    • DNA replication:
      • DNA strand unzips, and each strand acts as a template
      • DNA makes identical copies of itself
      • 2 new daughter strands of DNA form
  • Creation of proteins: made up of amino acids
    • Most human DNA is noncoding (only ~5% contains protein-coding)
    • Transcription:
      • One parental strand of DNA unzips, exposing 2 daughter strands of DNA
      • Free-floating RNA nucleotides match daughter strand
      • mRNA moves out of nucleus into cytoplasm
    • Translation:
      • mRNA enters cytoplasm, attaches to a ribosome
      • tRNA recognize and bind with complementary base pairs of mRNA
      • Amino acids form a chain (polypeptide) through peptide bonds, allows a “stop” codon for the protein to be completed
  • Methylation: attachment of a methyl group (chemical) to DNA at certain sites
  • Epigenetics: how the environment can result in heritable changes without alteration in the genome throughout the genome; represses the expression of certain genes
    • Caused by external/environmental factors (eg, extreme temperatures, disease, smoking, etc.)
    • Does not change DNA sequence, only gene expression
  • Microsatellites: sequences of repeated base pairs of DNA, usually no more than 2-6
    • Important when identifying bodies
  • Karyotype: complete set of chromosomes for an individual organism/species (typically 23 pairs, 46 chromosomes)
    • Contain all autosomes and one pair of chromosomes (determine biological sex)
      • Ie, females have 2 X chromosomes, males have 1 X and 1 Y
      • Patriline: lineage/inheritance traced from father to son via Y chromosome
    • Autosomes: nonsex chromosomes
  • Structural genes: coded to produce body structures (eg, hair, blood, other tissues), enzymes, and hormones
    • Regulatory genes: determine when structural genes are turned on and off for protein synthesis
      • Ie, if genes that determine bones didn’t turn off at a certain point, bones would continue to grow beyond normal
  • ABO blood system: each person has one A/B/O allele on one chromosome of the homologous pair, and another A/B/O on another chromosome of that pair
    • Antigens: proteins on the surfaces of cells that stimulate the immune system’s antibody production
      • Antibodies: part of primary immune system, respond to foreign substances and attach to foreign antigens
      • Determine which blood types we can receive in transfusions (eg, given blood type A, we can only receive A and O blood because our cells have anti-B antibodies)
      • Codominant phenotypes: two different alleles equally dominant (eg, AB blood type)
  • Pleiotropic: one gene has multiple biological effects
  • Polygenic: one phenotypic trait affected by 2 or more genes
  • Phenomes: the total set of phenotypic traits in an organism
    • Influenced by genes and environmental factors
  • Genes > DNA > chromosomes > genomes

Chapter 4: Genes and Evolutionary Change

• Deme: local population of organisms with similar genes, interbreed, and produce offspring
• Microevolution: small-scale evolution occurring from one generation to the next (eg, changes in allele frequency)
• Macroevolution: large-scale evolution occurring after hundreds/thousands of generations (eg, a speciation event)
• Equilibrium: a system is stable, balanced, and unchanging (no mutation)
  • Population must be large, or genetic drift will happen
  • Hardy-Weinburg law of equilibrium: relationship between frequencies of alleles and of genotypes; can determine if a population is undergoing evolutionary changes
• Patterns of natural selection:
  • Directional selection: favoring one extreme form of a trait/allele over others, causing allele frequencies to shift in one direction
  • Stabilizing selection: favoring the average version of a trait, decreasing genetic diversity for a trait in a population (against extremes)
  • Disruptive selection: individuals at both extreme ends of the range produce more offspring, which may lead to a speciation event (and those in the middle fail to survive)
• Sickle-cell anemia: deformed blood cells with a decreased ability to carry oxygen to tissues
  • Found in those with hemoglobin S allele
    • AS have much higher survival rates than those who don’t carry the S gene (red blood cells are poor hosts for malaria)
• Types of mutation:
  • Point mutations: incorrect base pairings; may or may not affect the amino acid the triplet codes
    • Synonymous point mutation: substituted nitrogen base creates a triplet coded to produce the same amino acid as the original triplet
    • Nonsynonymous point mutation: triplet coded to produce a different amino acid than original
    • Frameshift mutation: change in a gene due to insertion or deletion of one or more nitrogen bases; causes triplets to be rearranged and codons to be read incorrectly during translation
  • Transposable element: mobile pieces of DNA that can copy into entirely new areas of the chromosomes
• Exogamous: population where individuals only breed with nonmembers
  • Leads to large breeding population and genetic drift isn’t strongly occurring
• Endogamous: population where individuals only breed with members
  • Leads to small breeding groups with less possible genetic recombination

Chapter 5: Biology in the Present

• Cultural adaptations: learned behaviors to help us adapt
• Developmental adaptations:
  • Nutritional adaptation:
    • Basal metabolic requirement (BMR): minimum energy needed to keep a person alive
      • Needs additional energy for other functions (eg, exercise, growth, reproduction)
    • Total daily energy expenditure (TDEE): BMR and all other energy requirements
    • Macronutrients: carbs, fats, proteins
    • Micronutrients: vitamins and minerals
    • Malnutrition: affects (adult) height
    • Overnutrition:
      • High cholesterol (hypercholesterolemia): predisposing for coronary heart disease
      • Type 2 Diabetes: body doesn’t produce enough insulin/cells don’t use enough insulin, causing buildup of glucose in cells (weight gain)
      • High blood pressure
  • Skeletal adaptation: training bones
• Acclimatory adaptations:
  • Heat stress:
    • Vasodilation: increase in blood vessels’ diameter, able to move more blood away from body’s core to surface
    • Sweating and hairlessness: evaporation of sweat cools surface
    • Body shape: Bergmann’s (body proportions) and Allen’s (limb length) rules
      • Warm climates: taller, narrower body (maximize body’s surface area and promotes heat dissipation)
      • Cold climates: shorter, wider body (minimize surface area and promotes heat conservation)
  • Cold stress:
    • Vasoconstriction: decrease in blood vessels’ diameter, reduces blood flow and heat loss from body’s core to the skin
    • Shivering: produces heat
    • Elevated basal metabolic rate (BMR): high protein and fat, low carbs
    • Clothing and shelter
  • Skin Coloration (radiation)
    • Rickettes: soft and weakening bones due to vitamin D deficiency and lack of UV radiation exposure
    • UV radiation
      • Helps synthesize vitamin D
        • Necessary for proper skeletal development
      • Depletes folic acid
        • Necessary for DNA synthesis and spinal development
    • Melanin: darker in high levels, lighter in low levels
  • High altitude: larger lung capacity/chest cavity (more efficient use of oxygen)
• Sexual dimorphism: a difference in a physical attribute between the males and females of a species
  • Eg, most males tend to have larger body sizes than females