Part 2 Evolution The Challenge of Understanding Human Origins

Part Outline  Chapter 4 Field Methods in Archaeology and Paleoanthropology  Chapter 5 Macroevolution and the Early Primates  Chapter 6 The First Bipeds

Chapter 4 Field Methods in Archaeology and Paleoanthropology

Chapter Outline  How Are the Physical and Cultural Remains of Past Humans Investigated?  Are Human Physical and Cultural Remains Always Found Together?  How Are Archaeological or Fossil Remains Dated?

Artifacts Express facts of human culture:  What people do with the things they have made.  How they dispose of them.  How they lose them.

The Nature of Fossils  A trace or impression of an organism of past geologic time preserved in the earth’s crust.  Involves the hard parts of an organism: bones, teeth, shells, horns, and the woody tissues of plants.

How Organisms Are Preserved  Frozen in ice like the famous mammoths found in Siberia.  Enclosed in a fossil resin such as amber.  Preserved in lake bottoms and sea basins where accumulated chemicals create an antiseptic environment.  Mummified in tar pits, peat, oil, or asphalt bogs.

Locating Sites: Clues  Irregularities of the ground surface.  Unusual soil discoloration.  Unexpected variations in vegetation type and coloring.  Ethnohistorical data - maps, documents, and folklore.

Finding Clues  The plan of an ancient posthole pattern and depression at Snaketown, Arizona—permits reconstruction of the hypothetical house.

Methods for Dating Remains  Relative dating - determines the age of objects relative to one another.  Chronometric dating - determines the absolute age of an object.

Prehistoric Pottery Decoration  Coastal people twisted fibers used to make cordage to the left (Z-twist), while those living inland did the opposite (S-twist).

Methods of Chronometric Dating  Radiocarbon analysis - measures carbon 14 that remains in organic objects.  Potassium-argon analysis - measures radioactive potassium that has decayed to argon in volcanic material.

Methods of Chronometric Dating  Dendrochronology - based upon tree rings.  Amino acid racemization - based on changes from left to right-handed amino acids in organic materials.