Presentation on theme: "Paleoanthropology: Reconstructing Early Hominid Behavior and Ecology"— Presentation transcript:
1 Paleoanthropology: Reconstructing Early Hominid Behavior and Ecology Chapter 9Paleoanthropology: Reconstructing Early Hominid Behavior and Ecology
2 Chapter Outline Definition of Hominid The Strategy of PaleoanthropologyPaleoanthropology in Action—Olduvai GorgeDating MethodsExcavations at OlduvaiExperimental ArchaeologyReconstruction of Early Hominid Environments and Behavior
3 Definition of HominidCharacteristics significant in defining hominids:Large brain sizeTool making behaviorBipedal locomotion
4 Patterns of Evolution Mosaic evolution Biocultural evolution Evolutionary pattern in which physiological and behavioral systems evolve at different rates.Biocultural evolutionBiology makes culture possible and developing culture further influences biological evolution.
5 Biocultural Evolution: The Human Capacity for Culture The earliest hominids of 7-5 m.y.a. did not regularly manufacture stone tools.Stone tools appear in the archaeological record about 2.5 m.y.a.The dynamics between neuronal reorganization, tool use, changing social organization, and communication form the core of biocultural evolution.
6 PaleoanthropologyPaleoanthropologists use the skills of several disciplines to reconstruct the anatomy, behavior, and ecology of our ancestors:Geologists work with anthropologists to locate potential early hominid sites.Archeologists excavate the site and search for hominid traces.
7 Dating MethodsPaleoanthropologists use two types of dating methods to tell us the age of sites and fossils:Relative dating determines only whether an object is older or younger than other objects.Chronometric (absolute) dating provides an estimate of age in years based on radioactive decay.
8 Relative Dating Techniques Stratigrapy - based on the law of superposition, that a lower stratum (layer) is older than a higher stratum.Fluorine analysis applies to buried bones and groundwater seepage. Bones incorporate fluorine during fossilization.Biostratigraphy - related to changes in the dentition of animals.Paleomagnetism - based on the shifting of the geomagnetic pole.
9 Chronometric Dating Techniques The age of an object can be determined by measuring the rate of disintegration:Potassium/argon (k/Ar) dating involves the decay of potassium into argon gas. K/Ar has a half-life of 1.25 billion years.Carbon-14 is a radiometric method commonly used by archeologists. Carbon 14 has a half-life of 5730 years.
11 Paleoanthropology in Action-Olduvai Gorge Yielded the greatest quantity of high-quality data on early hominid behavior.The earliest hominid site dates to about 1.85 m.y.a., and is accompanied by the Oldowan tool industry.The most famous hominid fossil from Olduvai is the Zinjanthropus skull, discovered by Mary Leakey in 1959.
12 Excavations at Olduvai Three broadly defined site types present at Olduvai.“Butchering” localities - one or a few large mammals associated with archaeological traces.Quarry localities - areas where hominids obtained stone and initially fashioned stone tools.Multipurpose localities (“campsites”) - where hominids carried out daily activities.
13 Stone Tool (Lithic) Technology The most commonly preserved aspect of hominid cultural behavior.Initially, archaeologists thought the Oldowan industry consisted of deliberately fashioned cores and flakes.Richard Potts believes that only the flakes were being deliberately produced, and the “core tools” were merely byproducts of flake manufacture.
17 The Bipedal Adaptation Efficient bipedalism among primates is found only among hominids.All the major structural changes required for bipedalism are seen in early hominids from East and South Africa.Some researchers believe these early humans also spent considerable time in the trees.
18 Possible Factors Influencing the Evolution of Bipedalism Speculated InfluenceCarrying objectsUpright posture freed the arms to carry various objects (including offspring)HuntingCarrying weapons made hunting more efficient; long-distance walking may have been more energetically efficient
19 Possible Factors Influencing the Evolution of Bipedalism Speculated InfluenceSeed and nut gatheringFeeding on seeds and nuts occurred while standing uprightCoolingVertical posture exposes less of the body to direct sun; increased exposure to breezesVisual surveillanceStanding up provided better view of potential predators as well as other group members
20 Possible Factors Influencing the Evolution of Bipedalism Speculated InfluenceLong-distance walkingCovering long distances was more efficient for a biped than for a quadruped; mechanical reconstructions show that bipedal walking is less energetically costly than quadrupedalismMale provisioningMales carried back resources to dependent females and young