THE HOMINIDS

Ardipithecus ramidus

5.8-4.4 Mya Distribution: Ethiopia Very similar to chimps Molar are apelike: Canines are more

hominid-like Bipedalism- maybe

Australopithecus afarensis

Australopithecus afarensis

3.9 – 2.9 Mya Climate changing. Antarctic ice cap

advance 5 Mya Distribution: Ethiopia, Kenya, Tanzania Cranial capacity: 380 – 450 cm3

Height: 1.07m Bipedal (footprints 3.6 Mya old) /climber U-shaped dental arcade but reduced

canines Arboreal / terrestrial herbivore

Lucy

Lucy is the most complete skeleton of an early hominid. Found in Hadar, Ethiopia (1974).

Australopithecus afarensis Found in many areas of East Africa. 4.0 – 3.0 mya.

Lucy was a small-brained biped. Small brain 380 – 500 cc Lucy was 3’6” tall 50 lb Dates to 3.2 mya

Australopithecus africanus

Australopithecus africanus

3 – 2.25 Mya Cooling of climate reduced rainfall Further advance of Antarctic ice Appearance of Arctic ice 2.4Mya Development of scrubland and

savannah Forest cover retreats

Australopithecus africanus

Distribution: Southern and Eastern Africa Cranial capacity: 500 cm3

(Chimp = 400cm3) Bipedal 20 – 35 kg Rounder skull Parabolic dental arcade Longevity: 40 years maximum Scavenger of bone marrow/brain cases Used simple tools

Homo habilis - the handy man

Homo habilis

2.6 -1.4 Mya E. Africa Scavenging significant part of the

diet Cranial capacity: 600 – 800 cm3

Height: 1.20 – 1.35m Simple fashioned tools – choppers

(Oldowan culture)

Homo erectus – the upright man

Homo erectus

1.8 to 0.5 Mya 0.9 Mya beginning of the Pleistocene

ice age Oscillations between cold and warm

periods Spread out of Africa (1.6Ma)

throughout the old world Scavenging to hunting Use of a home base

Homo erectus Cranial capacity: 850 – 1100 cm3

(H. sapiens = 1350 cm3) Use of fire Height 1.55 to 1.8m Extended childhood 1st molar at 4.6 years old (H. sapiens =

5.9y) Greater longevity 52 years Speech? (Brain says: yes; spine says: no) Improved tools: Hand axes

(Acheulian culture)

Homo neanderthalensis

Homo neanderthalensis

250 000 to 28 000 years ago Europe, Middle East, into Central Asia Evolved from H. erectus populations

perhaps via H. heidelbergensis, then became extinct

Adapted to the ice-age conditions of temperate zone

Large nose may have warmed cold air The enigma of its extinction is not

explained

Homo neanderthalensis

Cranial capacity: 1400 cm3 (H. sapiens = 1350 cm3)

Brow ridge, long low skull Height: 1.67m Stocky build Improved sophisticated tools

(Mousterian culture) Sometimes buried their dead Made simple jewelry

Homo sapiens

Homo sapiens

From 150 000 years ago to present Originating in Southern Africa then went

worldwide Reached Europe about 50 000 years ago Cooling of the climate during the last

glacial period from about 50 000a led to their predominance over other species (e.g. H. neanderthalensis)

Omnivore Alters environment Domestication of species, farming

Homo sapiens

Cranial capacity: 1350 cm3 (range 1000 to 2000 cm3)

20% of the body’s energy consumption for 5% of body mass

Speech Art Extensive tool kit including new materials

(bone, ivory, antler) Symbolic thought 1st molar tooth 5.9 years old Longevity 66 years

Many Species coexisted

THE CHANGING TREES OF HUMAN EVOLUTION

1960 Up the ladder The idea that one

species smoothly evolves from one into another is regarded today as an oversimplification

Unfortunately it is a very persistent view that continually resurfaces in cartoons

Public Domain Images

Up the ladder

Australopithecus

Homo erectus

Homo sapiens

1970 Branching out

The 1960s and 1970s were a fertile period for fossil hunting in Africa

The idea developed that more than one hominid species existed at the same time developed

Homo sapiens

Homo erectus

Homo habilis

Australopithecus africanus

A. robustus

A. boisei

Australopithecus afarensis “Lucy”

Added 1974

1991 Changing status

As more specimens were found a clearer idea developed of the relationships between them

Homo sapiens

Homo erectus

Homo habilis

A. africanusA. robustus

A. boisei

Australopithecus afarensis

2001 From a tree to a bush

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1 Ma

2 Ma

3 Ma

4 Ma

Homo sapiens

Homo erectus

Homo habilis

A. africanus

P. robustusParanthropus boisei

Australopithecus afarensis Australopithecus anemensis

Ardipithecus ramidus

P. aethiopicus

Homo rudolfensis

H. ergaster

H. heidelbergensis

Homo neanderthalensis

A. garhi?

??

2003 DEEPER ROOTS

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1 Ma

2 Ma

3 Ma

4 Ma

5 Ma

6 Ma

7 Ma

Homo sapiens

Homo erectus

Homo habilis

A. africanus

Paranthropus robustusParanthropus.

boisei

Australopithecus afarensis

Australopithecus anemensis

Ardipithecus ramidus

P. aethiopicus

Homo rudolfensis

H. ergaster

H. heidelbergensis

Homo neanderthalensis

A. garhi

Orrorin tugensis

Gorilla gorilla

Sahelanthropus tchadensis“Toumai”

Pan trogolodites

Why does it keep changing?

New Fossils Better understanding of Evolution of

other species

How many more?

An estimated number of 16 hominid species is thought to have existed

This is based on the evolutionary patterns of other primates

Our family tree is similar to other species

Periods of radiation Separated by periods of extinction

Why is our record so incomplete?

Fossils must be easily accessible Must be preserved well enough to

be identified Must be politically or legally

accessible

GENETIC VERSES CULTURAL EVOLUTION

Mousterian tools Jonzac, France

Comparison

GENETIC CULTURAL

The product of natural selection

The product of learning. the transmission of acquired behaviour characteristics

Darwinian Lamarkian

Innate not modified during the organism’s life time

Learned during the life time

Passed on through hereditary information

Passed on to kin (family), social group, population, within a generation and between generations

Slow change Fast change

The relative importance of genetic and cultural evolution for humans

Not limited to humans examples found amongst birds and non-human primates

Genetic evolution determines features such as basic anatomy e.g. maximum cranial capacity that in turn will determine “intelligence”

Hominid cultures are associated with particular tools

Homo habilis Oldowan culture

Simple choppers, scrapers and flakes

Homo erectusAcheulian culture

Hand axes, cleaver and pick added to the tool box

Homo neanderthalensis Mousterian culture

Large flakes of uniform size produced from a core; these were then trimmed to the desired tool

Homo sapiens Soultrian culture

Delicate blades formed, knives, burins (for drilling); other materials added (bone, antler, and ivory). Some tools now ceremonial

This implies genetic evolution had to precede cultural evolution

Development of cultural innovation sometimes occurs a long time after the species evolves genetically

But when it happens it spreads quickly

Observed evolution of cultures

Example

Homo sapiens evolved a large cranial capacity and modern brain structure 150,000 years ago

Signs of symbolic thought processes in sculpture, wall paintings and adornments do not appear until 35,000 years ago

A fundamental change is thought to have occurred about 60,000 to 70,000 years ago

But is this an artefact of preservation?

Trends in Human Evolution

Anatomical Feature

Ape-like form Human-like form

Position of foramen magnum

Towards back of skull

Towards the base of the skull

Foramen Magnum

Trends in Human Evolution

Anatomical Feature

Ape-like form Human-like form

Position of foramen magnum

Towards back of skull

Towards the base of the skull

Cranial capacity Small Large

Canine teeth Long and sharp Short and dull

Molars Long and narrow Short and wide

Brow ridge Protruding Flat

Face below brow Protruding Flat

Jaw Tall and thick Small and thin

Changes in brain size and diet

Larger brain= more energy required More meat in diet

More meat= more hunting More hunting= more complex tools

and more complex social structure So: Increasing brain size led to

increase of meat in diet

Cooking

Cooking food releases more nutrients to be absorbed

Came later with discovery of fire Large brain size is needed

Are humans primates?

Yes 1. Opposable thumbs= fine motor

skills 2. Shoulders with full range of

motion= greater mobility 3. Forward facing eyes=

stereoscopic vision and depth perception