Paleoanthropology: ReconstructingEarly Hominid Behavior and Ecology

The earliest evidence of hominids dates to the end of the Miocene and includes dental and cranial pieces.

Learned behavior Non-body adaptations to the

environment. Identified among our closest ape

relatives.

A pattern of evolution in which the rates of evolution in one functional system vary from those in other systems.

LocomotionModern Homo

sapiensBipedal: shortened pelvis; body size larger;

legs longer; fingers and toes not as long

Early hominid Bipedal: shortened pelvis; differences from later hominids, smaller body size and long arms relative to legs; long fingers and toes; probably capable of considerable climbing

Miocene, generalized hominoid

Quadrupedal: long pelvis; some capable of considerable arm swinging, suspensory

locomotion

BrainModern Homo

sapiensGreatly increased brain size—highly

encephalized

Early hominid Larger than Miocene forms, moderately encephalized; prior to 6 m.y.a., no more

encephalized than chimpanzees Miocene,

generalized hominoid

Small compared to hominids, but large compared to other primates;

a fair degree of encephalization

DentitionModern Homo

sapiensSmall incisors; canines further reduced; molar tooth enamel caps thick

Early hominid Moderately large incisors; canines somewhat reduced; molar tooth enamel caps very thick

Miocene, generalized hominoid

Large front teeth (including canines); molar teeth variable, depending on species; some have thin enamel caps, others thick enamel caps

Toolmaking BehaviorModern Homo

sapiensStone tools found after 2.5 m.y.a.; increasing trend of cultural dependency apparent in later

hominids Early hominid In earliest stages unknown; no stone tool use

prior to 2.5 m.y.a.; more oriented toward tool manufacture and use than chimpanzees

Miocene, generalized hominoid

Unknown—no stone tools; probably had capabilities similar to chimpanzees

Paleoanthropology is the study of early humans.

This field uses many aspects of other disciplines Physical Sciences Biological

Sciences Social Sciences

Geology Physical anthropology Archaeology

Geomorphology Ecology Ethnoarchaeology

Geophysics Primatology Cultural anthropology

Chemistry Psychology

Taphonomy

Artifacts Objects or materials made or modified for use by

hominids. Taphonomy

The study of how bones and other materials came to be buried in the earth and preserved as fossils.

Context The environmental setting where an archaeological

trace is found.

Zinjanthropus cranium, discovered by Mary Leakey at Olduvai Gorge in 1959.

Paleoanthropologists use two types of dating methods to tell us the age of sites and fossils: Relative dating Chronometric (absolute) dating

Stratigrapy Fluorine analysis Biostratigraphy Paleomagnetism

The age of an object can be determined by measuring the rate of disintegration: Potassium/argon (k/Ar) Carbon-14 Thermoluminiscence

This site, more than 1 million years old, was located when a hominid ulna (arm bone) was found eroding out of the side of the gorge.

Grouped into categories:1. “Butchering” localities2. Quarry localities3. Multipurpose localities

A dense scatter of stone and some fossilized animal bone from a site at Olduvai, dated at approximately 1.6 mya.

Arrows indicate implement edge.

Environmental Determinsim Stable Carbon Isotopes

Factor Speculated InfluenceCarrying Upright posture freed the arms to carry

various objects.

Hunting Systematic hunting is now thought not to have been practiced until after the origin of bipedal hominids.

Seed and nut gathering

Feeding on seeds and nuts occurred while standing upright.

Factor Speculated InfluenceFeeding from bushes Upright posture provided access to seeds,

berries, etc., in lower branches; analogous to adaptation seen in some specialized antelope.

Thermoregulation(cooling)

Vertical posture exposes less of the body to direct sun; increased distance from ground facilitates cooling by increased exposure to breezes.

Factor Speculated InfluenceVisual surveillance

Standing up provided better view of surrounding countryside (view of potential predators as well as other group members).

Long-distance walking

Covering long distances was more efficient for a biped.

Male Provisioning

Males carried back resources to dependent females and young.

Factor Speculated InfluenceCarrying Upright posture freed the arms to carry various

objects.

Hunting Systematic hunting is now thought not to have been practiced until after the origin of bipedal hominids.

Seed and nut gathering

Feeding on seeds and nuts occurred while standing upright.

Efficient bipedalism as the primary form of locomotion is seen only in hominids.

Advantages of bipedalism: Freed the hands Wider view Cover long distances efficiently

Bipedalism as the only form of hominid terrestrial locomotion.