Digging Up the Past: Paleoanthropology and Archaeology

Lecture Objectives Identify the importance of fossil in understanding the behavior and anatomy of ancient hominins. Identify the differences between paleoanthropology and archaeology. Compare the similarities and differences between relative and chronometric dating. Be able to identify and describes examples of relative and chronometric dating.

Paleoanthropology and Fossils

Paleoanthropology Biological anthropology focus: study of earlier hominids, including 1. 2. 3. 4. Highly _____________

What do paleoanthropologists examine? FOSSILS Remember Cuvier – he recognized that fossils were once living organisms BUT fossils were not important in the realm of science until William Smith (engineering surveyor) Fossils are: Remains of organisms Organisms which were wholly or partially transformed into rock through a long process of chemical replacement

Why Fossils? What information do they hold? Provide direct ______________ Study of fossil centered on two factors Time  Environment 

Taphonomy & Fossilization Commonly bones and teeth sources (comprise 99 % of fossil record) Taphonomy 1. 2. Hominid collapses & dies on shore After the soft-tissue remains decay, only the skeleton is left. Footprints are left in the mud Water level rises, and lake sediments settle & cover the hominid’s bones and footprints Erosion exposes deep strata in a geologic column, revealing the fossil skeleton and footprints Bones fossilize in the thick layer of sediment at the bottom of the lake, while sediments continue to the deposited as layers. Other geological processes can occur, such as volcanic eruptions. As this happens, the fossil is embedded in a geologic stratum.

Dating Methods

Dating – Why Bother? Placing sites and fossils into a time frame Dating techniques Relative Dating  Chronometric Dating (numerical dating)  What is the numerical age? Isotope Dating  rate at which various ___________ _____________________________________

Relative Dating Tells the paleoanthropology that something is older or younger than something else Does provide: 1. 2. Does not provide:

Relative Dating #1: Stratigraphy Study of __________________________ Variety of locations can be compared via chemical, physical and other properties Law of _______________ Lower stratum (layer) is older than a higher stratum Problems Earth distributions Length of time to accumulate stratum

Relative Dating #2: Biostratigraphy Employs the associations of fossils in strata to determine each _________________ Aim is ________________ Why? Demonstrates that a particular geological section in one location represents the _______________ as another geological section at some other section

Relative Dating #2: Biostratigraphy Index Fossils – _____________________ Example of Irish Elk (died out: 10,600 yBP in Europe)

Relative Dating #2: Seriation Typological sequences of artifacts Assumption: ___________________ Frequency of co-occurrence of artifacts in specific contexts _____________________ Indicator of ____________________

Relative Dating #2: Seriation Example: Contextual seriation Pottery -- style rather than function

Numerical Dating Dating technique that gives an estimate in actual numbers of years _______________________ We will cover both isotopic and non-isotopic methods: Radiocarbon Radiopotassium Argon-Argon Why is this method useful? Certain radioactive isotopes of elements are unstable, disintegrate, & form an isotopic variation of another element Radioactive materials forms an accurate geological time clock

Numerical Dating #1: Radiometric Carbon isotopes: Ratio of 14C to 12C is measured Baseline for start of clock – death of organism By calculating the ratio of 14C to 12C one can determine ______________________________ Used for material younger than 50,000 – not the best for primate and human evolution Archaeologists NOT __________________

Numerical Dating #2: Radiopotassium Non-organic material (e.g. igneous (volcanic) rock) 40K decays slowly from its unstable form to a stable gas, 40Ar  __________________________ Dates material older than _________________ Note – cannot date sedimentary rock First used at ____________________

Numerical Dating #3: Argon-Argon 40Ar – 39Ar: volcanic rock is bombarded with “fast” neutrons in a nuclear reactor Advantage: ______________________________ Example: ______________________

Numerical Dating #3: Argon-Argon