What about Humans?

• Somewhere about 40

million years ago,

early primates—such

as the one pictured

here, began to evolve

to fit new

environmental niches.

Early Primates

• Prosimians (65mya)

• Monkeys (35mya)

• Apes (23mya)

• Hominids (5mya)

Australopithecus Afarensis

About 3.5 million years

ago the first primates

to exhibit bi-pedalism

appeared on Earth.

What advantages are

there to bi-pedalism?

Our backs and knees

work better as knuckle

walkers.

Climatic Change and Evolution

• One particularly

intriguing idea is that

Homo species evolved

as the climate changed

from Moist and

tropical to dry and

cooler.

• Why would this be

important?

Early Primates - Traits

• Common physical primate traits:

– Dense hair or fur covering

– Warm-blooded

– Live young

– Suckle

– Infant dependence

• Common social primate traits:

– Social life

– Play

– Observation and imitation

– Pecking orderCommon Primate Traits

Primate Family Tree

Crown lemurOrangutan

Evolution of Bipedalism• Anatomical 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

Bipedalism

Tools

Language

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)S

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Hominid Evolution• Major Homo advances:

– Brain size

– Better bipedalism

– Hunting

– Fire (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. erectus

• Finds 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 erectus

1891 - Eugene Dubois discovers H. erectus in Java

Dubois calls it Pithecanthropus erectus initially, also dubbed ―Java Man‖

finds in China called Sinanthropus

dates 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 yBP• Why was H. erectus so successful?

– Less sexual dimorphism = possible pair bonds, marriage

– Less hair on body = wearing of furs, other clothing

– Wearing of furs = ability to live further north

– Quick adaptation to environment without physical changes

– Culture is main reason H. erectuswas so successful

• organization for hunting

• ability to protect against predators

• control of fire?

• possible campsites

• tools (Acheulean industry)

Distribution of H. erectus

Homo neanderthalensis

• discovered in the Neander Valley (Tal) near Dusseldorf, 1856

• massive 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 cave

Bottom: 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

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 SapiensRegional-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.

Modern Humans

• Well, we still like to

argue all these points

as we learn about

them!