bio anth

• geological time scale

  -Paleozoic Era (ancient life-trilobites): 545-245 mya

  -Mesozoic Era (middle life-dinosaurs): 244-66 mya

  -Cenozoic Era (recent life): 65 mya - now
• cezanoic era

  -7 epochs (at least)

  *Paleocene

  *Eocene

  *Oligocene

  *Miocene

  *Pilocene

  *Holocene

  *Pleistocene

  -Primate evolution began 66 mya during Paleocene

  -Human evolution began 7 mya during Miocene

  -We are currently in Holocene
• when did human evolution start?

  late miocene
• when did primate evolution start?

  paleocene; 66mya
• what period are we currently in?

  holocene
• fossils


  remnants of organic materials that have wholly or partially been transformed into rock
• fossilization processes


  Oxygen free environment

  Rapidly covered (soil/rocks)

  Submerged in water

  Protected from scavengers
• dating methods


  -relative dating

  -absolute dating

  -genetic dating
• relative dating methods

  -Stratigraphy & Steno's Law of Superposition

  -Biostratigraphy

  -Flourine Dating
• stratigraphy


  -the study of rock layers and the sequence of events they reflect

  -oldest layers on bottom

  -youngest layers on top
• superposition


  -used to determine the relative age of rock strata, or layers

  -a principle that states that younger rocks lie above older rocks if the layers have not been disturbed
• fluorine dating


  -a relative (chemical) dating method that compares the accumulation of fluorine in animal and human bones from the same site

  -recently deposited bones will have had little time to absorb fluorine

  -fossils that have been in the soil longer will have absorbed greater quantities of fluorine

  -the amount of fluorine in bones at the bottom will be much greater than the bones near the top
• absolute dating techniques


  radiometric dating:

  -uses constant measurable change in an element as a clock

  half-life:

  -amount of time for one-half of an unstable (radioactive) isotope to decay into its stable counterpart

  genetic dating:

  -molecular clock: genetic mutations accumulate over time at more or less constant rate

  -date divergences of species
• biological species concept


  a group of actually or potentially interbreeding individuals that are reproductively isolated from other such groups
• speciation


  -the transition from an ancestral species to a descendant species

  -evolutionary process in which populations evolve into their own distinct species

  -requires:

  *variation in environment (food, climate, predators)

  *natural selection producing differing phenotypes

  *reproductive isolation
• disruptive selection


  -form of natural selection in which a single curve splits into two

  -occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle
• reproductive isolation


  separation of a species or population so that they no longer interbreed and evolve into two separate species
• phyletic gradualism


  -small changes accumulate over millions of years to produce new species

  -A->B->C linear
• cladogenesis


  -branching evolution

  -A->B, A->C (V shaped)
• adaptive radiation


  -species into many niches

  -example: Darwin's finches
• punctuated equilibrium


  rapid speciation events followed by long periods of stasis
• hallmarks of bipedalism

  Human-Ape (Chimpanzee) Comparison

  -Skull

  -Pelvis

  -Knee

  -Foot

  - Teeth
• skull

  Humans: smaller

  Apes: larger, longer
• foramen magnum


  Humans: on the bottom of the cranium

  Apes: toward the back of the cranium
• palate shape


  Human: U-shaped; arched

  Apes: rectangle shaped; parallel posterior tooth rows
• pelvic shape


  Human: bowl-shaped, shorter, broader

  Apes: longer, thinner, narrow
• femur & knee

  Human: femur angles in toward the midline of the body and centers the knees under the body; valgus (medial) angle

  Apes: straight femurs and knees positioned more toward the lateral sides of their bodies; straight
• valgus angle


  increased angle of femur allows legs to be under body and allow more efficient walking and running
• foot

  Human: short, straight toes and nondivergent hallux (big toe); longitudal arches

  Apes: long, curved toes and a divergent hallux that is used for grasping; flat feet - no longitudal arch
• non-divergent 1st digit


  in line (parallel) with other toes
• longitudal arch


  -extends down the length of the foot from the base of the toes to the heel

  -helps with shock absorption as we walk

  -helps to direct our body weight and energy to create a smooth push-off while stepping forward
• teeth

  Humans: do not have a C-P3 complex; small, non-projecting canine' no diastema

  Apes: C-P3 honing complex: the lower canine and P3 sharpen the upper canine every time the primate closes their mouth; long, projecting canine; diastema
• african apes at the end of the Miocene and how they survived

  Gorillas: reinvade forests and become folivores

  Chimps and Bonobos: become arboreal and terrestrial; they have a more general use of their environment

  Our ancestors: bipedalism, become terrestrial and arboreal
• why did our ancestors adapt to bipedalism? (hypotheses)

  -free hands to carry children, food, tools

  -access to arboreal food from the ground (no need to climb)

  -more energy efficient (ex: sun only hits shoulders)

  -walk between trees

  -see over high grass
• first possible primates

  Cenozoic Era (66 mya - present)

  Paleocene (66 - 56 mya)

  -Plesiadapis

  -Carpolestes simpsoni
• first true primates


  Eocene (56 - 34 mya)

  - lemur and tarsier like forms

  *Adapis (adapid): lemur like

  *Shonshonius (omomyid): tarsier like
• when was evolution of the anthropoids?

  oligocene (34-23 mya)
• when was evolution of hominoids?

  miocene (23-5.3 mya)
• climatic change & adaptation in cenozoic (eocene, olidocene, miocene)

  -Natural cycles of warming and cooling

  Eocene:

  -temperature increase= tropical forests and tree dwelling creatures

  Oligocene:

  -temperature plunged

  -forests replaced by grasslands so primate ancestors adapt to this

  Miocene:

  -drastic reduction in sea level and temperature increase

  -possibly related to the adaptation of bipedalism
• Early Hominins