Hominid Evolution

Early Primates

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

Early Primate 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 order Common Primate Traits

Primate Family Tree

Crown lemurOrangutan

1. Australopithecus afarensis Cranium

2. Australopithecus africanus Cranium

3. Homo habilis Cranium

4. Homo erectus Cranium

5. Neandertal Cranium

Hominid Evolution

Gorilla Pan Homo

5 – 7 mya

What features distinguish humans from the other apes?

Gorilla Pan Homo

Some major characteristics of hominid evolution

•Jaw shape

•Bipedal posture

•Reduced size difference between the sexes

•Brain size

•Family structure

Range

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In the course of primate evolution,there has been a trend toward longer periods of juvenile dependency

AdultJuvenileInfancyGestation

Two main groups of hominids

Homo (2.5 mya)Australopithecines (4 mya) (Australopithecus, Paranthropus)

Australopithecus

Gracile

small boned ape-like forms(A. africanus, A. afarensis)

Robust

ape-like forms(A. boisei, A. robustus)

A. boiseiA. africanus

Australopithecines are divided into two groups

A. robustus

Skull specialized for heavy chewing

large cheek teeth

large jaw

robust zygomatic arches

prominent saggital crest

Skull morphology suggests a more generalized approach to food

A. africanus

smaller molars

absence of bony crests for heavy chewing

•Discovered in 1924 by Raymond Dart in S. Africa

•Probably walked fully erect

•Humanlike hands and teeth

•The brain was only about 1/3 the size of modern human’s brain

Australopithecus africanus 3 – 2.3 mya

Taung Child

Were human ancestors hunted by birds?Research provides a break in the case of a famous hominid’s death

Australopithecus afarensis 4 - 2.7 mya

Afar region of Ethiopia (Donald Johansen, 1974)

“Lucy” complete skeleton of adult female

Diet: Soft fruit, nuts, seeds, tubers and bird eggs.Size: M: 152cm / 45kg F: 107cm / 28 kg.

Upright posture predates an enlarged brain in human evolution

3.5 my old Hominin footprints in the volcanic ash in Laetoli, Tanzania

Lucy skeleton

paleoanthropologists have found hominid species that predate A. afarensis

1994A. anamensis was

discoveredby Maeve Leakey in KenyaLived just over 4.2 – 3.9

mya

Found:Upper/lower jawsCranial fragmentsUpper and lower parts of leg bone

1995, Ardipithecus (possibly predates A. afarensis)

2001, Kenyanthropus platyops (3.5 – 3.2 mya)

Australopithecus anamensis

Australopithecus garhi

Discovered 1996

Berhane Asfaw & Tim White

Ethiopia Afar Basin

Garhi means “surprise”

Prehominid 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

Why Bipedalism?

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)

– Body temperature and bipedalism (Wheeler)

– Habitat variability and bipedalism (Potts)

– Reproduction and bipedalism (Lovejoy)

– Canine reduction and bipedalism (Jolly)

Muscle Functions

Gluteus maximus – Straightens & supports the hip joint & involved in walking

Gluteus medius – Rotate & balance the trunk over the single supporting limb & foot

Quadruceps femoris – extend & straighten the knee joint

Femur not angled in quadrupeds

Ardipithecus ramidus

Discovered by Tim White 1995

Oldest known hominid (about 4.4 million years ago)

Fragments of skull remains and skeleton found in theAfar Depression in Ethiopia

ramid = root (Afar), ardipithecus = ground, floor (Afar)

Possibly bipedal

Heavily forested, flood plain environment

Which of the australopithecines were evolutionary dead ends and which were close to or on the lineage that eventually sprouted the Homo branch?

evolutionary dead end?

Australopithecus aethiopicus

2.5 mya

-Found in 1985 by Richard Leaky &

Alan Walker

-Lake Turkana in Northern Tanzania

-Commonly called the black skull

Australopithecus boisei

Discovered 1959

Mary Leakey

East Africa at the Olduvai Gorge in Tanzania

Also found in Ethiopia and Kenya

Lived 2.6 - 1.2 mya

Called Zinjanthropus boisei, but later changed to Australopithecus boisei.

Often referred to as Paranthropus boisei

Australopithecus robustus

Discovered 1938

- Robert Broom

- Often referred to as Paranthropus robustus

- Lived 2-1 mya

And now…

the Hominids

The earliest fossils that anthropologists place in Homo are classified as Homo habilis

•Discovered by the Mary & Louis Leaky in 1964

•Existed from 2.5 – 1.6 mya in E. Africa

•Teeth were smaller and the brain was significantly larger

•5 feet tall & 100 lbs average

•Less prognathic jaws and larger brains than australopithecines

•Sharp stone tools have been found with these fossils (Oldowan tools)

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

                                                             

Oldowan tools

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.

Anatomical characters unique in Homo

• An increase in cranial vault height and thickness • Reduced lower facial prognathism • Reduction in the size of premolars and molars

and the length of the molar row • Increase in brain size

Homo erectus was the first hominid to migrate out of Africa

•Lived from 1.8 mya– 500,000 ya

•Discovered by Eugene Dubois in 1891

•Fossils from Asia are known as “Beijing man” and “Java Man”

•Compared to H. habilis, H. erectus was taller, had a larger brain, and were less sexually dimorphic

Nature, 2002

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 industryPhotograph 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. 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 erectus

Most fossils found in the Lake Turkana

region of northern Kenya

trends linking erectus with sapiens includes

• An increase in brain size (erectus approximately 900 cc., sapiens approximately 1350 cc.)

• A reduction in postcanine dentition, and a correlated

decrease in jaw size • Vertical shortening of the face • Shortening of arm-bones (especially the forearm) to come

to a very humanlike limb proportions

• The development of a more barrel-shaped chest. • The formation of an external nose. • Reached modern human size in terms of height.

Homo Erectus

1st to control use of fire which lead to:• Better health• Better hunting• Warmth in colder climates

In Europe Homo erectus gave rise to the Neanderthals

Neanderthals (200,000 - 30,000 ya) settled throughout Europe, Middle East, and parts of N. Africa

When and where did anatomically modern humans originate?

Figure 34.41 Two hypotheses for the origin of anatomically modern humans

(emerge btwn. 160,000-154,000 ya,)

Multiregional vs Out of Africa

• How exactly hominids spread into the rest of the world from Africa, is still unknown. The two possible theories for this occurrence are discussed in more detail in The Multiregional Hypothesis and the "Out of Africa" Hypothesis.

• Multiregionalism defends the side that represents no single origin for modern humanity, whereas the "Out of Africa" hypothesis states that humans originated in Africa and then slowly developed their modern forms in every area of the Old World some 200,000 years ago.

How are Neanderthals related to us

If Neanderthals and Cro Magnons encountered one another in Europe (30,000 ya), and they interbred, Neanderthal MtDNA Sequences would have entered the modern human gene pool.

There is no genetic evidence of interbreeding. Genetic studies have shown that we are genetically distinct from Neanderthals

How are Neanderthals related to us

Anatomical evidence corroborates the genetic results that Neanderthals did not contribute to the ancestry of modern Europeans

MtDNA sequence variation supports single-origin theory of modern human evolution

Fossil evidence indicates modern human morphology emerged in Africa long before the Neanderthals vanished from Eurasia

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

• 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

Neanderthals vs

Cro Magnons

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

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?)

Thomas Sutikna (the Indonesian Centre for Archaeology) and Homo floresiensis