Biological Anthropology Flashcards

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

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

Genetics

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)

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

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

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