Final Exam Flashcards
Fossilization Process
calcium/phosphate in bone -> rock forming minerals (iron/silica). 1. death and soft-tissue decay. 2. Skeleton is covered by lake sediments. 3. Rock-forming minerals from water begin to replace calcium-phosphate of bone. 4. Skeleton fossilizes as lake sediments continue to be deposited as layers. 5. Erosion exposes the deep strata in which fossil is located. 6. Excavation and analysis by physical anthropologists
Mineral Composition of bone
65-75% mineral
Mineral Composition of teeth
97% mineral
Ideal Environments for Fossilization
remains covered soon after death, protection from scavengers, oxygen-free environment limits decomposition, avoid acidic groundwater/soils that dissolve bone/teeth
Morphological species concept & how it’s used to group fossil species
Assuming that species look similar because they share genes. Gene exchange->species->similarity and vice versa.
Risks of defining paleospecies
allometry-study of the change in proportion of various parts of an organism as a consequence of growth. sexual dimorphism-morphologically different fossils may be male and female examples of the same species. interspecies variation- interbreeding-capable individuals may look different due to environmental adaptations, random variations, or trauma.
Gradualism
Darwin’s theory that species are constantly and slowly changing, and that these changes eventually “add up” to a new species. ex: human evolution
Punctuated Equilibrium
Stephen Gould’s theory that species are not changing very much. They rapidly evolve into new species in short periods of time. Species suddenly exposed to very different environment. Mutations for very different phenotypes are suddenly spread by natural selection. “The Cambrian Explosion”- huge increase in diversity in a short amount of time.
Law of Superposition
Nicolaus Steno- the lower the layer of rock, the earlier in time it was deposited. Lower fossils are older.
Disturbances to superposition
Erosion. Intrusion.
Relative Dating
what is the order of the fossils? Based on the relationship with fossils or other artifacts
Stratigraphic Correlation
Order of layers determined by looking at many sites. Paraconformity- a layer representing time was eroded away or not deposited at a site
Biostratigraphy
Index fossils- known dates. First and last appearance and/or morphological change. Rock containing an index fossil must fall within that range.
Cultural Dating
material culture produced by humans also has known date ranges. Rock contains artifact= falls within date range of that artifact.
Absolute Dating
What is the approximate age of a fossil? Does not require other fossils.
Radiometrics
isotope- atoms with a different number of neutrons (carbon 12, carbon 13). Half-life- how long it takes for 1/2 of the radioisotopes in a substance to decay
radiocarbon dating
Carbon-14 Dating. organic material absorbs carbon-14 by breathing small amounts of atmospheric C02. We know original C14 to C12 ratio at death: same ratio in atmosphere and living things. Compare specimen to original ratio and see how much C14 has decayed. Useful for dating materials 50,000 yBP to 1950 AD
potassium-argon dating
Potassium bearing minerals. Igneous rock= argon gas driven off by volcanic heat. All K-40 solid -> All Ar-40 gas: Proton -> Neutron, half life of 1.3 billion years, rocks older than 200,000 years
argon-argon dating
K-39 appears in same amount in igneous rock as K-40. Also 1.3 billion year half-life. Nuclear reactor bombards K-39 with neutrons, converts it to Ar-39, Measure Ar-40 to Ar-39 ratio. Advantages: less rock needed. Don’t need to measure potassium.
Fission track dating
Uranium 238 splits and leaves tracks on rock crystal. Uranium-bearing minerals. Laser measures uranium content. Equation with how much of this Uranium has split = age. Half-life of 4.5 billion years. Date rocks up to 3 mya
dendrochronology
temperature/cold regions. Growth stops in winter, leaves a ring. One ring= one year. requires excellent preservation of tree sections. Date between 12,000 to 8,000 years ago.
paleomagnetic dating
Random reversals of the Earth’s magnetic field. Normal vs reversed North-South polarity. Metal grains align with magnetic field as they settle into sedimentary rock. Banding pattern matched fossil collection. Date sedimentary rocks younger than 5 mya.
genetic dating
molecular clock- rate of mutation in DNA for a species. # base pairs mutated per 1 million years. Number of differences between a species- years since those species diverged.
radiometric techniques-
use radioactive decay
non-radiometric techniques
do not use radioactive decay
Hominidae
Great apes, humans, and ancestors
Hominini
humans and human ancestors. Different from apes: oblige bipeds, non-honing chewing complex, significant brain size increase, complex culture, speech
Origins of bipedalism
foramen magnum: more anterior (bottom of skull) on biped, more posterior (back of skull) on quadruped. Vertebral column: S-shaped in biped, C-shaped in quadruped. Vertebrae: Larger at bottom in biped, same size in quadruped. Angle of femur: biped has values knee with more than 90 degree angle, quadruped has varus knee with a 90 degree angle to femur. Acetebelum: larger in bipeds. Bipeds have short, wide pelvis, quadrupeds have a long narrow one. Bipeds have longer legs than arms, quadrupeds have arms slightly longer than legs. Bipeds have an adducted hallux, quadrupeds have an abducted (opposable) hallux. bipeds have double arched feet, quadrupeds only have a transverse arch.
Quadrupeds have more curved phelanges than bipeds.
Darwin’s hunting hypothesis
bipedalism was naturally selected so humans could carry tools and weapons for hunting. Problem: hunting and tools appeared much later than bipedalism
patchy forest hypothesis
savannah like environment at end of miocene caused loss of food. Bipedalism allowed humans to travel further and become more energy efficient.
thermoregulation hypothesis
stand upright= less exposure to solar regulation, wind blows heat off head. Regulation of body temperature. Problem: less useful in woodlands where humans first evolved.
male provisioning hypothesis
males provide food and resources for females. bipedal= male can carry food back to offspring while mother cares for children. Problem: assumes monogamous pairs occurred before bipedalism.
Brain evolution
larger brains evolved along with complex speech and fine motor skills
enlarged cerebellum
muscle memory, larger in humans, smooth overhand throwing while hunting. fine motor control for tool making
cerebrum
motor movements, senses, cerebral cortex folding is increased in humans: more surface area= more room for neuron connections.
profrontal cortex
intellect, complex learning, recall, working memory, personality
speech centers
broca’s area-controls muscles that produce speech. wernicke’s area- comprehends and plans speech. Broca’s and Wernicke’s areas are both found in the left hemisphere of 95% of people.
hypotheses for brain evolution
increased access to food- better food= bigger brain. familiarity of home range and knowledge of when foods are available. Social brain- living in social groups requires complexity for social interactions and alliances. Meat eating- proteins and fats = larger brains. Problems- why didn’t other species evolve under similar pressures?
Encephalization
brain/body size ratio. (EQ) Animals with an EQ larger than 1.0 have a larger brain size than predicted for their body size. Apes have an EQ larger than 1.0
FOXP2
produces a protein that regulates gene expression.
Sahelanthropus tchadensis
Time Period: central and east Africa (7-6mya) Primitive Features: small brain, massive brow ridge, sagittal crest, less prognathic than an ape Derived Features: foramen magnum more anteriorly placed, non-honing chewing complex, thicker enamel.
Orrorin tugenensis
Time Period: Tugen Hills, Africa (6.0 mya) Primitive Features: Derived Features: long femoral neck= bipedal but curved phalanges suggests time spent in trees. Non-honing canines, small teeth with thick enamel.
Ardipithecus ramidus
Time Period: Awash River Valley, Ethiopia (4.4 may) Palmigrade tree climber and terrestrsial biped. Primitive Features: feet-opposable hallux and only one arch, curved phalanges and grooves for knuckle walking, moved on hands and feet in trees. Derived Features: non-honing chewing complex, small, blunt canines, thicker enamel, anterior foramen magnum, s-shaped lumbar curve, shorter broader pelvis.
Australopithecus afarensis
Time Period: 3.6-3.0 mya, east africa. Primitive Features: small femoral head, small acetebulum, equal length arms and legs, intermediate phalange curvature, glenoid fossa in shoulder oriented upwards. Derived Features: anterior foramen magnum, s-shaped vertebral column, valgus knee, long femoral neck, wider, shorter pelvis, adducted hallux, longitudinal arch.
Australopithecus boisei
Time Period: Primitive Features: Derived Features:
Australopithecus africanus
Time Period:3.0-2.0 mya (same time as garhi, boisei, and aethiopicus. Taung Child fossil. Primitive Features: gives rise to robust but still has some gracile features. Derived Features: bipedal (anterior foramen magnum, short wide pelvis, valgus knee, adducted long hallux.
Australopithecus robustus
Time Period: 2.0-1.5 mya. High level of sexual dimorphism. Primitive Features: Derived Features: sagittal crest, massive flat face, large molars, small incisors, thick enamel
Australopithecus garhi
Time Period: 2.5 mya, East Africa. Primitive Features: prognathic face, small brain, large teeth Derived Features: more humanlike arm/leg ratio, radius/ulna and femur longer than lucy. Tool use.
Australopithecus sediba
Time Period: 1.97-1.98 mya South Africa. Primitive Features: Gracile Features, pelvis and small molars similar to homo erectus. Derived Features: diet similar to modern chimps, mostly C3 plants.
Australopithecines
Eastern and Southern Africa, 4-1 mya, bipeds, small canines, small brained/bodied, large premolars/molars,
Oldowan Tools
use one stone to knock flakes off a core. Australopithecus garhi 2.6 mya ethiopia.
Robust vs Gracile Australopithecus
Robust skull differs where chewing muscles attach. No body size difference between robust and gracile. Robust: emphasized chewing muscles, emphasized nuchal crest, more vertical face, large chewing surfaces, dietary hypothesis: based on dental micro wear. Robust had large reliance on grasses which required a lot of grinding
reconstructing diet
tooth wear. C3 plants: leave low ratio of C13 to C12; wet woodland plants, leaves, fruit, herbs. C4 plants: leave high ratio of C13 to C12 in bone; grassland plants.
Homo habilis
Time Period: 2.5-1.8 mya Primitive Features: short leg/arm ratio, Derived Features: reduced prognathism, larger forehead, more gracile skull, dietary shift and/or use of tools, brain size increase, large incisors.
Homo Erectus
Time Period: 1.8 mya- 300,000. Longest lived hominid and first to leave Africa. Primitive Features: Derived Features: reduction in face/jaw size. Increased brain size. increased supraorbital torus. decrease in tooth size. potential for first human gait. Short arms/long legs.
archaic homo sapiens
Mixture of earlier H. Erectus and later Anatomically Modern Human (AMH) traits. Time Period: Primitive Features: Derived Features: less robust cranium, prognathism reduced. eventually divides into neanderthals and AMH
neanderthals
Time Period: 130,000- 30,000 yBP low forehead, low arching brow ridge, projecting mid face, large front teeth, lack of chin, large cranial capacity, occipital bun. Extremely robust post-cranium.
What set homo apart?
increased brain size, brain sits higher in cranium, round/high forehead, reduced prognathism, clear tool use. Smaller teeth, complete loss of diastema, thicker enamel.
Achuelean stone tool industry
1.8 mya, much more complex than oldowan. bifaced: flaked on both sides. sharper cutting surface.
controlled use of fire
460,000-230,000 BP why fire? expansion into colder areas, releases more nutrients/easier to chew. burned items: animal bones, stone tools, plants, charcoals, ash, ostrich egg shells, hackberry seeds,
mousterian stone tool industry
300,000-30,000 invented by archaics. Chip edges off core. Replaced by acheulian techniques.
cold adaptations in Neanderthals
wide nasal aperture: warms and moistens cold air. large infraorbital foramina- greater blood flow to face to prevent freezing.
Out of Africa Model
Africa-200,000 yBP. Asia-90,000 yBP. Europe- 32,000 yBP. AMH evolved from archaic homo sapiens in Africa. Move to Asia and Europe to replace the archaic homo sapiens living there. limited admixture with Asian and European archaics.
Multi-Regional Continuity Model
Archaics in Africa, Europe, and Asia all evolved into AMH in those areas. Emphasizes gene flow (admixture) African, European, and Asian cultures.
Assimilation Model
“partial replacement” AMH evolve from archaics in Africa, then migrated to Asia and Europe. Extensive admixture between AMH from Africa and European/Asian archaics
New Stone Tool Industries
Material Diversification. Heat Treatment-transformed poor quality silcrete into easily shaped material. Microlithic’s.
Cultural objects
shell beads-found in north africa, more than 25 miles from the mediterranean where they were made. some covered in red ochre. They were traded.
Behavioral Modernnity
symbolic thinking- cave paintings (aurignacian period-France), figurines, complex stone tool industry-aurignacian. (blades & micro blades), new material (bone antler). Migration. Coordination and planning- trade migration, hunting large animals. Abstract thinking- make and use symbols.
Plant domestication
control of the reproductive/and or growth cycles. increased seed size. weather changes an increased population size may have caused this.
animal domestication
not aggressive, selected for juvenile traits. increase size (meat). increased wool production. Dogs domesticated, then livestock.
effects of agriculture on the environment
environmental degradation- soil erosion, overgrazing, destruction of native vegetation, reduction in biodiversity needed to maintain the ecosystem.
effects of agriculture on the human skeleton
pathology. bone mass and strength decreases. Osteoarthritis decreases- physical activity and mechanical stress- joints degenerate. Infectious disease increases- population density increases cause disease, staph infections, tuberculosis, syphilis, dental enamel hypoplasia, iron deficiency anemia,
why switch to farming if it is so bad?
key components of evolution- survival of the reproductive years, production of offspring. Agricultural Revolution- settled lifestyle, more frequent births. Greater productivity and labor specializations.
Difference between bioarchaeology and forensic anthropology
bioarchaeology- study of historical and ancient human skeletal remains. Insights into nutrition, health, and activity. Forensic Anthropology: the scientific application of physical anthropology in a memo-legal context. Identify individual’s remains/ circumstances of their death.
MNI
minimum number of individuals. important in mass grave recovery.
PMI
Post mortem interval- time since death. Builds on process of taphonomy (burial, decay, preservation) Depends on: environment, climate, carnivore activity, human activity, other disturbances.
Biological profile
sex estimation: males are 20% more robust than females, most extreme differences in pelvis and skull. Age estimation: based on root formation, crown formation, and tooth eruption. Epiphyseal fusion: based on age which the epiphysis (ends) of long bone fuse to shaft. Cranial suture closure: Sutures of the skull fuse together from ages 20-60. Geographic ancestry: lot of variation in expression due to clines and admixture. Stature. Facial Reconstruction: pegs set to represent muscle thickness at 21 landmark areas. Based on average values.
Blunt Force Trauma
depression legions.
Sharp Force Trauma
contact with sharp instruments causes straight edge legions.
ballistic trauma
entry: round smooth shape. Exit: larger than entry, bevelled surface
Antemortem
Before death. smooth edges. callus.
Perimortem
Sharp edges. No callus.
Postmortem
after death
Fractures and Forces
Compression. Tension. Torsion. Shear.
