Human Evolution and PREHISTORY

Human Evolution Human Evolution andand PREHISTORYPREHISTORY

PART III: EVOLUTION OF THE GENUS PART III: EVOLUTION OF THE GENUS HOMO AND THE DEVELOPMENT OF EARLY HOMO AND THE DEVELOPMENT OF EARLY

HUMAN CULTUREHUMAN CULTURE

Human Evolution Human Evolution andand PREHISTORYPREHISTORY

Chapter Seven:Chapter Seven:

HOMO HABILIS HOMO HABILIS AND AND CULTURAL ORIGINSCULTURAL ORIGINS

Link to the Canadian Association for Physical Anthropology

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When, Where, And How Did Human When, Where, And How Did Human Culture Develop?Culture Develop?

When Did Reorganization And Expansion When Did Reorganization And Expansion Of The Human Brain Begin?Of The Human Brain Begin?

Why Did The Eating Of More Meat Lead Why Did The Eating Of More Meat Lead To Improved Brains?To Improved Brains?

EARLY REPRESENTATIVES OF THE GENUS EARLY REPRESENTATIVES OF THE GENUS HOMOHOMO

Olduvai Homo habilis, 1.8 my

650-690 cc cranial capacity

Modern-looking hands, feet

Little difference from Australopithecus in body size, sexual dimorphism, and tree-climbing abilities

Maturation rate closer to apes

Associated with stone tools

Olduvai Homo habilis, 1.8 my OH 24


KNM ER 1470, Lake Turkana, 1.9 my

752 cc cranial capacityCranium is more modern in appearance than in AustralopithecusAssociated with stone tools

KNM ER 1470 1470


KNM ER 1470, Lake Turkana, 1.9 my

Inside of the skull shows a pattern in the left cerebral hemisphere that is associated with the speech area and right hand control of living humans

Wear patterns on tools indicate predominance of right-handedness

Brain was reorganized along human lines

Relations between Relations between Homo habilisHomo habilis and and AustralopithecusAustralopithecus

There is no agreement on what distinguishes Australopithecus from

Homo

One approach is to use the following characteristics:

Absolute brain size greater than 600 ccUse of language and toolsPrecision grip distinct to Homo


Collard and Wood would define Homo by its adaptive zone

AustralopithecusBody mass and shape more suited to

closed environments, e.g. forestApe-like dietApe-like development patternCombined locomotion of bipedalism and

climbing


Collard and Wood would define Homo by its adaptive zone

HomoBody mass and shape more like ours,

suited to open habitatsDiet more like ourshuman-like development patternbipedalism


Marked increase in brain/body size ratio

Heat-exchange system to keep brain cool (only a rudimentary one in late gracile Australopithecines)

Smaller teeth in relation to skull size

Major brain-size increase and tooth-size reduction are important trends in the evolution of the genus Homo

Earliest fossils to exhibit these features appear by 2.4 mya (Baringo)

Relations between Relations between Homo habilisHomo habilis and and AustralopithecusAustralopithecusNone of the robust Australopithecines belong in the direct human lineage; they coexisted with Homo habilis from 2.5 to 1 mya, headed in two very different evolutionary directions

The body of Homo habilis had changed little from gracile Australopithecines; hence, they are likely suitable ancestors for Homo

Did Australopithecus afarensis or Australopithecus africanus give rise to Homo habilis?

Or was it Kenyanthropus (Chapter 6), to the exclusion of all Australopithecines (minority view)?

Relations between Relations between Homo habilisHomo habilis and and AustralopithecusAustralopithecusMost see early East African graciles as generalized enough to have given rise to both Homo habilis and robust Australopithecus

Homo habilis and robust australopithecines appear about the same time in the fossil record

At least a 3-way split was underway by 2.5 mya (see Figures 7.5 and 7.6 on next slides and in text)



LOWER PALEOLITHIC TOOLSLOWER PALEOLITHIC TOOLS

The beginning of the “Old Stone Age” is marked by the appearance of tools 2.6 million years old

Olduvai GorgeOlduvai Gorge2 million years ago Olduvai was a lake, whose shores were inhabited by robust Australopithecines, Homo habilis and later Homo erectus (chapter 8)

Assemblages of stone tools (2 mya) were found, associated with bones of now-extinct animals and with evidence of butchering

On an occupation surface, 1.8 mya, there was a “stockpile” of basalt stones, forming a circle

Oldowan Tool TraditionOldowan Tool Tradition Flakes were struck from a

stone either by using a hammerstone, or by striking the stone against a large rock (anvil), using the direct percussion method

It produced tools with sharp edges, effective for cutting and scraping

Microscopic wear patterns show tool use for cutting meat, grasses, wood

Oldowan ToolsOldowan Tools

Important technological advance for early hominins

Saving of labour and time

Addition of meat to diet on a frequent basis

Since dentition of Australopithecus and Homo is poorly suited for meat eating (e.g. small canines), sharp tools for butchering were needed

Tool UseTool UseProbably a result of adaptation to an

environment changing from forests to grasslands, 3-2 mya (see Figure 6.11)

Oldowan Tools and Bone AssemblagesOldowan Tools and Bone Assemblages

H. habilis and large carnivores were active at the same locations, based on combinations of toolmarks and gnaw marks

Whole carcasses of animal skeletons are not represented

Tools were made of materials that were procured at a distance

There was repeated use of sites over periods of 5-15 years

Suggesting that our Oldowan forebears were SCAVENGERS

Tools, Meat, and BrainsTools, Meat, and Brains

After 2.5 mya meat became an important part of the hominin diet

Early hominins lacked size and strength to compete for kills and to drive off predators, so must have relied on wit and cunning

ORIGINAL STUDY

Cat in the Human CradleCat in the Human Cradle

An anatomical analysis has suggested that both Homo habilis and A. afarensisi were better than us at climbing trees and suspending

Archaeological evidence from South Africa and observation of modern-day leopard activity support “tree-caching” as an ancient form of leopard behaviour in Africa

The collection of bones at Olduvai Gorge then could be explained by both ground scavenging and the scavenging of leopard “tree kills” by Homo habilis

““Man the Hunter”Man the Hunter”In the 1960s and 1970s the “man the hunter”

model for provisioning of the social group was supported, followed later by documenting the role of “woman the gatherer”

Cooperation in food procurement and division of labour by sex are seen as prime factors in the success of early Homo in this model

Since these factors relate to male-female differences in the distant past, they are generally attributed to biologically determined sex differences rather than gender

Tools, Meat, and BrainsTools, Meat, and BrainsBehavioural reconstructions from fragments of bone and stone rely on observations of living primates, human (e.g. modern food foragers) and nonhuman

It is likely that the culture of Homo habilis played a role in food-sharing behaviours, rather than strict biological male-female differences

Hominid Brain and Meat ConsumptionHominid Brain and Meat Consumption

Increase in brain size correlates with appearance of meat in the hominin diet

The human brain consumes more than twice the energy of the brains of nonhuman primates

Meat is more energy-dense than plant food, important for the evolving brain

Daniel Wolpert...The Real Reason for Brains

“You may reason that we have brains to perceive the world or to think, and that’s completely wrong.”

Hominid Brain and Meat ConsumptionHominid Brain and Meat Consumption

The most readily accessible plant sources were leaves and legumes, difficult for primates to digest

Chimps search for animal foods on the savanna; why not our ancestors, too?

Increased meat consumption ensured an adequate intake of essential amino acids and more leisure time for exploring the environment

These factors may have stimulated brain development, as indicated by significant increase in brain size in Homo habilis

THE EARLIEST SIGNS OF CULTURE THE EARLIEST SIGNS OF CULTURE AND TOOLSAND TOOLS

1. Problem solving, e.g. the use of stone tools to butcher and prepare meat

2. Tool manufacture, emphasizing manual dexterity and fine manipulation, resulting in improved organization of the nervous system

3. Abstract idea of the tool, plus the steps and materials to make it

Language OriginsLanguage OriginsImportance of cooperation, planning and

foresight for H. habilis raises questions about communication abilities

Humans and apes share a gesture-call system, inherited from the common ancestor

Humans and apes share language potential (apes to the level of a 2-3 year-old)

These shared abilities must have been possessed by the earliest hominins as well

Language and the Language and the Homo habilis Homo habilis BrainBrain

The speech area is adjacent to that involved in precise hand control

Manufacture of Oldowan tools require manual skills beyond those of chimpanzees using stones and anvils for nut-cracking (chapter 4)

H. habilis exhibited handedness in toolmaking which is associate with lateralization of the brain

Lateralization is associated with language

Wernicke’s area and Broca’s area are two areas in the brain associated with speech. Both are believed to have been present in the Homo Habilis brain.

Homo erectusHomo erectus and the and the Emergence of Hunting and Emergence of Hunting and

GatheringGathering

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Human Evolution and PREHISTORY