Chapter 2 –Human Evolution

Today’s ObjectivesHow do humans differ from apes?

Skeleton, organs, cultureWhy was Homo erectus so successful as an early hominid?What happened to Neandertals?Be able to briefly trace the cultural development of:

tools, fire, clothing, shelter, artWhat is so important about the Upper Palaeolithic?

Theories of Evolution

Origin Myths/CosmologiesGreek – PrometheusGenesis

Left: Prometheus and AthenaTop: God and Adam

Western examples

Carl Sagan’s Universe Calendar

24 days = 1 billion years1 second = 475 years

“Big Bang” January 1Milky Way May 1Solar System September 9Life on Earth September 25Humanlike Primates December 31, 10:30pm

Milky Way

Theories of Evolution

Darwin and Wallace, 1850sEvolution theory holds that existing species of plants and animals have emerged over millions of years from simple organisms.Darwin, On the origin of species, 1859Influenced by the principle of uniformitarianism

Charles Darwin

Theories of Evolution - CorollariesDarwin’s principle of natural selection

“Natural selection is the gradual process by which nature selects the forms most fit to survive and reproduce in a given environment.”

For natural selection to work on a given population, there must be variety within that population and competition for strategic resources.

The concept of natural selection argues that organisms which have a better fit within their environmental niche will reproduce more frequently than those organisms that fit less well.

Theories of Evolution - Corollaries

Random genetic drift is the loss of alleles from a population's gene pool through chance.

Mutation introduces genetic variation into a breeding population.

Gene flow occurs through interbreeding: the transmission of genetic material from one population to another. Gene flow decreases differences and inhibits speciation, the formation of new species.

Theories of Evolution - CorollariesMendel’s principle of inheritance, 1856

The science of genetics explains the origin of the variety upon which natural selection operates.

By experimenting with successive generations of pea plants, Mendel came to the conclusion that heredity is determined by discrete particles, the effects of which may disappear in one generation, and reappear in the next.

Other TheoriesCreationism accounts for biological diversity by referring to the divine act of Creation as described in Genesis.

Catastrophism is a modified version of Creationism, which accounts for the fossil record by positing divinely authored worldwide disasters that wiped out the creatures represented in the fossil record, who were then supplanted by newer, created species.

Intelligent Design states that modern physics and cosmology have uncovered evidence for intelligence in the structure of the universe and this intelligence seems to act with us in mind and that the universe as a whole shows evidence of design.

Early Primates

Prosimians (65mya)Monkeys (35mya)Apes (23mya)Hominids (5mya)

Early Primates - TraitsCommon physical primate traits:

Dense hair or fur coveringWarm-bloodedLive youngSuckleInfant dependence

Common social primate traits:Social lifePlay Observation and imitationPecking order Common Primate Traits

Primate Family Tree

Crown lemurOrangutan

Evolution of BipedalismAnatomical changes

Neck (1), chest (2), lower back (3), hips and

pelvis (4), thighs (5), knees (6), feet (7)

Theories

Tool use and bipedalism (Darwin/Washburn)

Energy efficiency and bipedalism (Isbell/Young)

Radiator theory (Falk)

Body temperature and bipedalism (Wheeler)

Habitat variability and bipedalism (Potts)

Reproduction and bipedalism (Lovejoy)

Canine reduction and bipedalism (Jolly)(Click for interactive skeleton)

Pre-hominid Evolution

Reconstruction of Australopithecine

Ardipithecus ramidus 4.4 - ? mya

A. anamensis 4.2 - 3.9

A. afarensis 4.2 - 2.5

A. bahrelghazali 3.5 - 3.0

A. africanus 3.5 - 2.5

P. aethiopicus 2.7 - 2.3

A. garhi 2.5 - ?

P. boisei 2.3 - 1.3

P. robustus 2.0 - 1.0

BipedalismToolsLanguage

Hominid Evolution

Homo habilis (2.0 – 1.6mya)

H. rudolfensis (2.4-1.6mya)

H. erectus (1.9-27kyBP)

H. heidelbergensis (800-

100kyBP)

H. neanderthalensis (300-

30kyBP)

H. sapiens (130kyBP – present)

Sca

le:

Mill

ions

of

Years

BP

Hominid EvolutionMajor Homo advances:

Brain sizeBetter bipedalismHuntingFire (H. erectus)Tools

Oldowon (H. habilis)Acheulean (H. erectus)Mousterian (H. heidelbergensis)Solutrean (H. sapiens)

Built shelters (H. heidelbergensis)Clothing (H. neandertalensis)Language (Neandertals?)

Homo habilis

Artist’s representation of a Homo habilis band as it might have existed two million years ago.

612 cc brain

2.3 - 1.6 mya

first toolmaker

prognathic face, brow ridge

probable meat-eater

possibly arboreal

discovered in 1960 by Leakeys

no speech

H. habilis v. H. erectusFinds in east Africa indicate that Homo habilis was not very different from the australopithecines in terms of body size and shape.The earliest Homo erectus remains indicate rapid biological change.

The fossil record for the transition from H. habilis to H. erectus supports the punctuated equilibrium model of evolution.H. erectus was considerably taller and had a larger brain than H. habilis.

Homo erectus1891 - Eugene Dubois discovers H. erectus in JavaDubois calls it Pithecanthropus erectus initially, also dubbed “Java Man”finds in China called Sinanthropusdates from 1.9 mya to 27,000 years B.P.994 cc brain size (compare to 612 for H. habilis)Acheulean tool industry

Photograph of Nariokotome boy, an early Homo erectus found near Lake Turkana, Kenya.

Homo erectus – 1.9mya to 27k yBPWhy was H. erectus so successful?

Less sexual dimorphism = possible pair bonds, marriageLess hair on body = wearing of furs, other clothingWearing of furs = ability to live further north

Quick adaptation to environment without physical changesCulture is main reason H. erectus was so successful

• organization for hunting• ability to protect against

predators• control of fire?• possible campsites• tools (Acheulean industry)

Distribution of H. erectus

Homo neanderthalensisdiscovered in the Neander Valley (Tal) near Dusseldorf, 1856massive brain--about 1,400cc on average

• large torso, short limbs, broad nasal passages

• later remains show decrease in robustness of the front teeth and face, suggesting use of tools replaced teeth

• retained occipital torus, some mid-facial prognathism

The skull of the classic Neandertal found in 1908 at La Chapelle-aux-Saints.

Neandertal Culture

• Homesites – In caves, also in

the open (near rivers,

framed with wood and

covered with skins)

• Burial – Is there evidence of

purposeful burial and ritual?

• Language – Could

Neandertals talk or not?

• Tools – Mousterian tradition

Top: Reconstruction of Neandertal burial from Shanidar caveBottom: Mousterian tools

What happened to Neandertals?

• H. neanderthalensis coexisted with H. sapiens

for at least 20,000 years, perhaps as long as

60,000 years

• What happened?

– Neandertals interbred with H. sapiens

– Neandertals were killed off by H. sapiens

– H. sapiens drove Neandertals into extinction by

competition

Homo sapiens

• Archaic – 100,000 to 35,000 years BP– Sometimes called

Homo sapiens and Homo sapiens neanderthalensis

• Modern – 35,000 years BP to present– Anatomically modern– Sometimes called

Homo sapiens sapiens

Cro-Magnon Man• Cro-Magnon humans

• 35,000 years B.P. in western Europe to 17,000 years B.P.

• 1,600 cc cranial capacity• Name comes from a hotel in

France• Not a different species, just old

Homo sapiens from Europe

Artist’s reconstruction of a Cro-Magnon man

Archaic H. sapiens Culture• Art

• Traces of art found in beads, carvings, and paintings

• Cave paintings in Spain and southern France showed a marked degree of skill

• Female figurines• 27,000 to 22,000 years B.P.• Called “venuses,” these figurines

depicted women with large breasts and broad hips• Perhaps it was an example of an

ideal type, or perhaps an expression of a desire for fertility

Archaic H. sapiens Culture

• Cave paintings– Mostly animals on bare walls– Subjects were animals favored for

their meat and skins– Human figures were rarely drawn

due to taboos and fears that it would somehow harm others

Cave paintings from 20,000 years ago at Vallon-Pont-d’Arc in southern France (left) and from Lascaux, in southwest France

Upper Palaeolithic – Hotbed of Culture• 40 – 10k yBP• Shelters

– 15,000 yBP Ukraine– Some made with mammoth

bones– Wood, leather working;

carpentry

• Tools– From cores to blades– Specialization– Composite tools– Bow and arrow

• Domestication of dogs • Gathering rather than hunting

became the mainstay of human economies.

Top: Straw Hut

Left: Mammoth bone hut

Bottom: Tool progression

Modern Homo Sapiens• Regional-Continuity Model (Milford Wolpoff, UMich)

• Humans evolved more or less simultaneously across the entire Old World from several ancestral populations.

• Rapid-Replacement Model (Chris Stringer, NHM London)• Humans evolved only once--in Africa from H.

heidelbergensis ancestors--and then migrated throughout the Old World, replacing their archaic predecessors. Also called the “Out of Africa” and “Killer Ape” hypothesis.

Social Organization

• Hunter-gatherer analogy– Small group, low population density,

nomadism, kinship groups

• Migration– North America was the last colonized by

hominids.– Beringia (land bridge) between Russia and

Alaska– Asian origin of Native Americans– 30,000 to 12,000 years B.P. was first

migration

Human Variation

• Modern humans vary in skin color, hair color, and eye color.

• Will talk about anthropological conceptions of race and ethnicity later in the semester (April 23).