Anthropology – Lesson 4
Relative dating: only relative of ordering objects. Something is older by something else, but doesn’t tell you how old the
thing actually is.
E.g. “A” is older than b and c, but won’t tell you A is 15,000 years old
Absolute dating: (chromatic dating) Provides age and actual date. It’s not absolute, there is an error range. Fundamental
type of info you can extract.
Subdivision of geology.
Studies of ordering of deposits. Think about processes that make up surface of earth, generally lay down a layer
Stuff you find may tell you the age of the geological site
o E.g. If flood, there is a layer of flood, or eruption – there is layer of lava.
o Human activities can produce layers – lay down all kinds of garbage.
Principle of super positioning:
Younger layers are on top of older layers.
Analogy: If you throw garbage every day in the same bin, there are layers. More towards the bottom, the older it
This idea can be wrong due to alterations in layers.
o E.g. human burial. Burial cut through the layer. When buried, the dirt used to cover up the hole disrupts
the layers. Folding of earth can flip the layers.
Stratigraphic Column: Ensure you know where stuff came from in respect with those layers. Fossils in deeper soils =
Physical correlation: ways to determining equivalency b/w parts of geographic sections and findings. Relate to ppt. It
ignores spatial scale
Iridium anomaly: 65 mil years ago, asteroid hit Mexico. Led to big cloud of dust on Earth. Enriched in asteroid surface
but rare in earth surface. This event cause huge extinctions. (not really related to anthro)
The law of Faunal Succession: find same fossil in 2 places that are far away, that means those strata (layers
underground) are in the same age. Rather than using geological event/layer, it uses fossils itself to determine age.
Biostratigraphy: e.g. context of human evolution and people study pigs b/c they give you age of fossils. Indicates human
Analogy: there is different style of cars from 1900 – 1970. Monday, October-01-12
Archeologists can use artifacts to determine how old the thing is.
Willard F. Libby: father of radiocarbon revolution. University of Chicago and studied radioactivity. How long do things
remain radioactive? Provided framework of radiocarbon dating.
All things are made of atoms:
2 kinds of particles:
o Positive – protons.
o Neutral – neutrons.
They weigh around the same.
Atom has 6 protons is atom of carbon. Atoms has 7 neutron is atom of nitrogen.
Combination of 2 things determines the weight of atom.
Atoms w/ same # of protons but # of neutrons can vary meaning the weight of atom can vary.
Carbon exists in 3 isotopes. Refer ppt. 12 carbon
Carbon 12 – 98.89% in nature consist of this type of carbon.
Carbon 14 has radioactive. Organic needs carbon.
When you die, you stop taking in carbon 14, and it starts to break down.
After you die, you go out of equilibrium in terms of proportions of carbon. And less and less radioactive in your
body as time goes on
Half-life: after 1 half-life, half of amount carbon isotope changed to daughter product. Refer to ppt for half-life (