chapt 4

Genetic dating

Consider time based on testing against present DNA, the Amount of mutations that are missing (we have more) determine how old person is. Assumes generation rate of 29 years.

Contamination before sampling

Depending on location (waterlogged areas) can skew carbon results, and throw off date.

World chronology

Follows human evolution, with skeletons, tools and living conditions. Most significant occurrence - food production by domesticating plants and animals.,

Chronological correlations

Ie combining results of 2 absolute dating methods together , gives largest results.

Segmentary societies

Ie farmers, small independents communities without strong organization

Context in deposition

Issues with radiocarbon arise often during excavation when archeologist doesn't no formation process. To talk about radiocarbon dating the person must be sure of the archaeological context - ie how was it buried, found.

Radiocarbon -

Most useful way of measuring dates, radiocarbon is C14,. Normal carbon is C12, and C13. Simply measure the rate o of radiocarbon decay (occurs with nitrogen) to get date. Will have less radiocarbon as days pass. ratio carbon dates it's half life to be 5568, radiocarbon is passed into all things by CO2,

Contamination during or after sampling

Must exclude modern carbon when containing sample like glue or carbon wax, green mold on samples after storage=contamination

Fission track dating

Records spontaneous fission (division) or radioactive uranium atoms, cause item to be damaged, so this measures the damage, or tracks.

Ranked societies or chiefdom

Social units had difference, because mess egalitatrian, had diff in status and importance,. Still term used for non urban areas.

Global connections : ie tephrachronology

Tell time between items and compare it to natural disasters that happened at the same time, ie seen with trees around volcano, reduce growth rate and ring size that year.

Date of context

The radiocarbon date could me measuring when it was created, not when it was used for. Ie reuse of logs, measures date centuries before it was used = bad,.

Potassium argon dating

Used to date rocks, about measuring potassium and argon decay, used to find early human sites, however has an error estimate of about 30 thousand years, and can only really measure volcanic rock

Uranium series

Used to measure uranium decay, ie calcium carbonate rocks, within the time period of 500-50 thousand years ago, measures isotopes by counting alpha emissions, have error rate of 12-25 thousand years off depending on age. Limit= has to measure items close to caves, which can skew age because it's difficult to determine order of disposition. Can also measure teeth.

3) seriations

also plays with 'like goes with like' and association. allows assembligaes of artifacts to be arranged in order - which then indicates date. seen on cemetary designs. frequency seriation : changes in popularity

absolute dating: historical chronology : terminus post quem'/cross dating/ terminus ante quem

artifacts that actually have a date/reflection of time on it (pottery with king on it).' terminus post quem' (date after which) seen with coins, date on the coin is the date it was made, not date it represents. cross dating: cosidering the export or import of artifacts to extend chronological links. considers a pot in greece from egypt, must consider the terminus ante quem: ie date before which, must have been made before

Calibrated relative methods

1) Amino acid racemization: dates human/animal bone/shell, can study things a million years old, living items have L organisms, dead have D organisms. So they measure the ratio of L to D organisms to get date, 2) archaeomagnetic dating: based on direction and intensity of earths magietic feild. Hardly used, this feild is recorded in any baked structure,

absolute dating: relative dating doesnt state how old something is in actual 'years'. therefore methods of absolute dating : 3

1) calanders 2) tree rings 3) radiocarbon ( for palelithic, they use potassium-argon dating, uranium, and genetic)

How to calculate radiocarbon dates

1) measure radiocarbon date (as per trees) and error estimates (error considering counting error, cosmic radiation..) in +/-, able to give you age related to calander. States 1950 as present.

measuring time:

1) radioactive clocks: what date do archeologists see as year 0? seem to take on the date 'before 1950' - also the first year the radiactive method came about. (present = bp) 2) paleolithic period they use 1950 or our date interchangably, since its unlikely they can date sites within thousand year range.

relative dating:

1) stratigraphy 2) typological sequences 3)seriation 4) liguistic dating 5) climate and chronology

Absolute dating methods - others that aren't to great

1) thermoluminescence dating: used for crystals that have been fired,pots, clay, or burnt soil. The fire will collect and seal the radiation, will have radiocarbon clocks reset. 2) optical dating: used on items exposed to light, will contain the trapped energy that it was exposed to from the light 3) electron spin resonance dating: used for material that decompose when heated, like tooth enamel

Absolute dating naturally:

1) tree rings - called dendrocronology- lines aren't uniform. Because becomes narrower with age and depends on climate.

5) climate and chronology: a) pleistocene chronology

1)ice age, found four major 'glacials' = periods of glacial advance. however sometimes had warm intervals called 'interglacials'. smaller warm/cold periods are called 'stadials and interstadials'. therefore dated due to glacial sequences. (for warm places like africa, tied rainfall to glacial sequences to assume dates, rainfalls are called ' pluvials and interpluvials')

Ways of measuring tree rings and limitation

1. Long sequences and radio carbon - line up older trees with new trees by matching up lines, can calibrate radiocarbon dating. Limitation-can only be done away from tropics, because tree lines are more well defined. And to calculate the actual date, must have tree line that extends to present.

State societies

After urban revolution, societies has profound differences including governments and writing

Second radiocarbon revolution

Calibration between radiocarbon history and tree rings, realize radiocarbon in air fluctuates, which skews dates, so they track it against tree rings to get a sense of how much carbon was in the air that year

2) typological sequences: for artifacts

dating due to artifacts design style and type. 2 iteas: diff time and places have recognizable styles 2) change in style and shapes of items is gradual - evolutionary (darwin)'like goes with like'. good date indicators are items that change frequently ( weapons/pot designs)

1) stratigraphy : for sites

ie study of stratification - layers. the arrangment already states a chronological sequence (bottom to top). association is important, if 2 artifacts associate with eachother, we assume they are buried at the same general time. therefor if an object can be assigned a date, all associating objects and the layer have a date. however human pit distrurbances (spoil pits) makes dating hard.

4) linguistic dating: 3 types for language

language change - new words introduced and others gone - seen shakespear vs now. 1) 'lexicostatistics': study changes in vocabularty - take 200 words from each population, consider if they have same root terms.2) 'glottochronology' : uses a formula to pronounce how many years ago the two languages diverged. states "86% difference in 1000 year change. 3) network analysis:used to search for writing structure in historical data

5) climate and chronology: b) Deep sea cores and ice cores

most coherent way of recording climate dates is deep sea cores. 'foraminifera' : organisms that fill shells in deep sea cores, lay on the flood trough slow process of sedimentation. the variation in chemical structure of the shells date sea temperature, which date time. long time ago = stratification is hard to see.

5) climate and chronology: pollen dating

pollen ( never decomposes) is studied in swamps and bogs to state vegetation and climate. pollen zone: mass area that can tie to pollen sequences, one pollen sample date found = all of pollen zone.

relative dating

the idea something is older or younger relative to something else

absolute dating: 1) calanders and chronology ( 3 things to consider in chonology)

three main points when working with early civilization calanders through chronology (seen in egypt) : 1) needs careful reconstruction and any list of kings/leaders has to be reasonably complete. 2) the list of names has to be linked to our own calander 3)the artifacts found have to relate/associate with ruler of the time to be sure

the maya calander

very exact. uses two systems; the calender round: everyday life, 'sacred round' is 260 days, inside ciricle number 1-13, outside 20 days, solar year is 18 months (each of 20 days +5 days). and the long count: historical dates, date of zero is 3114 bc, seen the world ends in 2012.

absolute dating

ways to know the age in years bfore the presnet of diff events of parts of a sequence. helps us see how quickly change occurs.