Paleoanthropology The study of human origins and evolution, focuses on the tiny fraction of geologic time during which humans and diverged from a common ancestor.

Some Common Misconceptions • Human ancestors were chimpanzees – Chimpanzees and humans represent two divergent branches of the hominoid tree that evolved from a common ancestor that was neither a nor a human.

Some Common Misconceptions

• Human evolution is like a ladder with a series of steps leading directly from an ancestral hominoid to Homo sapiens.

•At times in hominid history, several different human species coexisted.

•Human phylogeny is more like a multibranched bush than a ladder, our species being the tip of the only twig that still lives. 0 Homo ? robustus ergaster 0.5 Paranthropus boisei 1.0 Homo 1.5 Australopithecus sapiens africanus Homo 2.0 Australopithecus neanderthalensis afarensis 2.5 Homo 3.0 Australopithecus erectus anamensis 3.5 Homo habilis 4.0 Kenyanthropus platyops 4.5 Ardipithecus 5.0 ramidus 5.5

6.0 Orrorin tugenensis

6.5 Sahelanthropus tchadensis 7.0 D.3.6: State that, at various stages in hominid evolution, several species may have coexisted. Hominid Evolution: the current view A modern view of human evolution maintains that it has

occurred as a series

of adaptive Megadonts radiations.

African apes

Early Bipedal

Apes Time (millions (millions ofyears) Time

Diversity Hominid Evolution: the current view The 1st radiation: is that of the early bipedal apes – including the gracile Australopithecines. Megadonts

African apes

Early Bipedal

Apes Time (millions (millions ofyears) Time

Diversity Hominid Evolution: the current view The 2nd radiation: involved the robust Australopithecines, a group of species that exploited low-grade vegetable food Megadonts sources (nuts, root tubers and seeds) African apes resulting in species Early Bipedal with very large teeth Apes

(megadont). (millions ofyears) Time

Diversity Hominid Evolution: the current view 3rd radiation: is genus Homo, developing a larger brain, diversifying, and Megadonts dispersing from Africa to other African apes Early parts of the Old Bipedal Apes

World. (millions ofyears) Time

Diversity Hominid Evolution: the current view 4th radiation: does not involve any major evolutionary Megadonts divergence, but

reflects the African apes dispersal of Early Bipedal modern humans Apes worldwide. (millions ofyears) Time

Diversity Genus Homo became extinct Modern humans Hominid about 35,000 arose 150,000 to Holocene years ago 100,000 years ago 0 Homo Homo sapiens Evolution neanderthalensis

0.5

Many human Robust Australopithecines 'prototypes' exist regionally Archaic A greatly Homo sapiens 1

simplified Pleistocene Split by some into depiction of Homo erectus and Homo erectus Paranthropus hominid Paranthropus robustus 2 boisei Split by some into evolution. Homo habilis and Homo rudolfensis Homo habilis (1470 )

Paranthropus aethiopicus Uncertainty as to whether present Million beforeyears Australopithecus

A. africanus was a direct 3 ? africanus human ancestor

A. afarensis ('Lucy') is the earliest currently

known human ancestor Pliocene Australopithecus A second sub-species afarensis (A.r. kadabba) 5.2-5.8 mya Possible hominid 4 near hominid/ape split at 6.0 mya ? Genus Homo ? ? Australopithecus Genus Australopithecus anamensis Orrorin Genus Paranthropus Ardipithecus tugenensis ramidus ramidus 6.0 mya 5 The Hominid Fossils

*We will only discuss a small selection of hominid fossils. There are others that time does not allow us to include.

There are 7 species of hominid for which we need to be familiar…

Ardipithicus ramidus

Date 4.4-5.8 mya Brain Size 300-350 cc

Height c. 1.22 m Physique Possibly bipedal forest dweller. Little else known.

Skull shape more forward than apes

Teeth and Teeth intermediate jaws between earlier apes and later hominids. Reduced canine teeth. Smaller, narrow molars; thinner jaw. Distribution Eastern Africa Reading: Oldest Skeleton of Human Ancestor Found Reading: Meet the new human family (Ardi section…)

Australopithecines are divided into two groups

Learn about us first!

A. africanus A. boisei

Gracile, small boned ape-like forms Robust, ape-like forms (A. africanus, A. afarensis) (A. boisei, A. robustus) RADIATION #1 RADIATION #2

Australopithecus afarensis

Date 3.9-2.5 mya Brain Size 400-500 cc

Height 1.07 – 1.52 m Physique Light build. Bipedal. Some apelike features: relatively long arms, curved fingers, sexual dimorphism*

Skull shape Apelike face, low , bony , flat nose, no chin Teeth and Canines smaller than apes, jaws larger than humans. Jaw shape half way between an ape and human

* Some researchers claim such differences in height suggest two separate species, not sexual Distribution Eastern Africa dimorphism. Jaw shape half way Sexual dimorphism between V-shape of in the canine teeth ape's and U-shape (a primitive trait) of human jaw Shoulder joint that is orientated Chest (thorax) towards the head is funnel- shaped Relatively long arms compared to legs

Wrist has high mobility Finger Relatively are curved short legs

Ankle joint is Toes are long highly mobile and curved

Redrawn from a photograph by © David L. Brill 1985 Australopithecus afarensis

Small brain (410cc) Low forehead

Brow ridge

Large, dish- shaped face Wide midface

Flat nose

Big, ape-like Little of the skull is incisor behind the foramen Diastema magnum (gap) Large, thickly Canines larger enameled molars than in humans A Modern Human Skull (for comparison)

Australopithecus africanus

Date 3.0-2.3 mya Brain Size 400-500 cc

Height 1.1 – 1.4 m Physique Light build. Probably long arms, more „human‟ features, probably less sexual dimorphism than A. afarensis Skull shape Brow ridges less prominent; higher forehead and shorter face. Teeth and Teeth and jaws much jaws larger than in humans; shape of jaw fully parabolic as in humans; canine teeth further reduced Distribution Southern Africa Australopithecus africanus

Small brain (450cc) same size as gorilla's but organization is No different from an ape's

Brow ridge

Low facial angle

Lower face protrudes forward into a snout Very large molars compared with (prognathism) modern humans (not shown here) A Modern Human Skull (for comparison) Australopithecines are divided into two groups

Now learn about us (even if IB doesn‟t care about us!)

A. africanus A. boisei

Gracile, small boned ape-like forms Robust, ape-like forms (A. africanus, A. afarensis) (A. boisei, A. robustus) RADIATION #1 RADIATION #2

A. robustus

A. boisei A. aethiopicus

Australopithecus robustus (AKA Paranthropus)

Date 2.2 – 1.5 mya Brain Size 530 cc

Height 1.1 – 1.3 m Physique Heavy build. Relatively long arms. Moderate sexual dimorphism.

Skull shape Long, broad, flat face. Crest on top of skull. Moderate facial buttressing. Teeth and jaws Thick jaw, small incisors and canines. Large molars.

Distribution Southern Africa A. robustus

Very prominent sagittal crest for the attachment of powerful jaw muscles Small brain (530cc)

Heavy brow ridge

Part of the rear and top of this skull is missing Low facial angle

Massive zygomatic arch and cheek bones

Little of the skull is behind the foramen magnum Small incisors (missing in this specimen)

Massive molars with thick enamel are well worn suggesting a tough A Modern Human Skull vegetarian diet (for comparison) Genus Homo

Homo habilis Homo neanderthalensis Homo ergaster

Homo erectus Archaic Homo sapiens Homo sapiens

Homo habilis

Date 2 – 1.6 mya Brain Size 500-800 cc

Height 1.0 – 1.5 m Physique Robust but “human” skeleton

Skull shape Small face with developed nose

Teeth and Narrow molars. jaws

Distribution Eastern and Southern Africa Homo habilis

Bigger brain Rounded cranium with no sagittal crest (650-680cc)

Bulge in the Broca's area Brow ridge of the brain for speech production Smaller, narrower face than the australopithecines

Flat nose

Projecting jaw More of the skull is behind (prognathism) the foramen magnum

Tooth row displays a Jaw is less massive than modern curve, with in the australopithecines narrow molars A Modern Human Skull (for comparison)

Homo erectus

Date 1.8 – 0.3 mya Brain Size 750 - 1250 cc

Height 1.3 – 1.5 m Physique Robust but “human” skeleton

Skull shape Flat, thick skull with sagittal “keel” and large brow ridge Teeth and Smaller teeth than H. jaws habilis

Distribution Africa, Asia, Indonesia and possibly Europe Homo erectus

Bulge in the Broca's Bigger brain Long, flattened cranium with a area of the brain for Earliest: 750cc distinctive keel along the top speech production Latest: 1250cc Bulge in Wernicke's Shelving area of the brain for forehead speech recognition Thick brow ridge

Flat face

Occipital lobe Projecting (bun-like swelling) jaw

Attachment for strong neck muscles to stop the head from sagging forward Teeth are smaller than A Modern Human Skull H. habilis, but more No chin (for comparison) massive than our own

In Europe, H. erectus gave rise to the Neanderthals

Homo neanderthalensis

Date 150,000 – 30,000 ya Brain Size 1250 – 1750 cc

Height 1.5 – 1.7 m Physique Robust but “human” skeleton, adapted for cold.

Skull shape Reduced brow ridge, midface projection, long low skull Teeth and Similar to H. sapiens, jaws larger jaw

Distribution Europe and western Asia Key 30,000 years ago Atlantic Ocean 30,000–35,000 years ago 35,000 years ago

Original discovery Approximate range of Neanderthals Europe Neander Valley

Black Sea

Mediterranean Sea

Africa Homo neanderthalensis

Large brain (1600cc) Low, long cranium Larger than a modern brain but organized differently Sloping forehead

Double-arched brow ridge Occipital lobe (bun-like swelling) Large prominant nose and mid-facial projection

Swept back, lightly built Skull widest at the base cheek bones (unlike modern which are widest near the top)

Powerful jaw but Weak chin reduced compared Teeth are smaller to H. erectus than H. erectus, but A Modern Human Skull bigger than our own (for comparison) Clavicle: long

Skeleton Shoulder joint: large

Scapula : wide Rib cage: Large and wide with more muscle

Hips: wide Elbow joint: large Hip joint: large, rotated outward Forearm: bowed and short

Hand: with strong grip Femur shaft: thick and wide fingertips walled, rounded and curved

Patella: large Tibia: thick-walled, and thick short and flattened

Toe bones: Ankle joint: large wide and strong

Photo courtesy of: Clones®

Homo neanderthalensis

The hyoid is a u-shaped bone suspended by ligaments from the styloids at the base of the skull. It lies between the and larynx where it anchors the muscles necessary for speech. This specimen is based on the 1983 discovery in Kebara Cave, Photo courtesy of: Bone Clones® Israel and is virtually identical to the hyoid bones found in modern humans. This important discovery demonstrates that Neanderthals had the capacity for speech and possibly language. Position of the hyoid bone Did Neanderthals interbreed with Homo sapiens?

Reading:

Neandertal Genome Yields Evidence of Interbreeding with Humans

Homo sapiens

Date 160,000 ya – today Brain Size 1200 – 1700 cc

Height 1.65 – 1.85 m Physique Modern skeleton adapted for warmth

Skull shape Small or no brow ridge, shorter and higher skull

Teeth and Small teeth, shorter jaw jaws than Naederthals, chin developed

Distribution Global Homo sapiens

Large brain Convex cranial vault (1400cc)

High, vertical Skull widest forehead high up No brow ridge, just a slight swelling of the

Vertical Low, rounded face occipital area

No muzzle (no prognathism) Sizable mastoid process

Reduced tooth size Sizable jaw with with thinner enamel projecting chin A Modern Human Skull (for comparison) Hominid Skulls Lab

What trends are seen in hominid evolution? 1. Increased adaption to bipedalism 2. Hair reduction 3. Reduced sexual dimorphism 4. Decreasing relative size of face, jaw, teeth, esp. canines; increasing relative size of brain case, forehead 5. Increase in brain size 6. Migration out of Africa

Trend #1: Increased adaption to bipedalism

– Bipedalism arose 4 million years ago in the first Aaustralopiths. A large brain evolved later. – What is the evidence for this? – Evidence from fossil trackways – Evidence from hominid fossils Ancient footprints Why Bipedalism?

A Change of Environment • About 20 million years ago, the Indian plate collided with Asia and thrust up the Himalayan range.

A Change of Environment

• The climate became drier and the forests of what is now Africa and Asia contracted. – The result was an increased area of savanna habitat, with fewer trees.

Why bipedality?

Increased visibility: see predators and prey Why bipedality?

Carrying food: Towards safety

Carrying offspring While tracking game herds

Hold tools /weapons Why bipedality? Thermoregulation The upright posture exposed less surface to the tropical sun.

Efficient Locomotion It is more economical than knuckle walking used by the other great apes. In a more fragmented woodland the hominids would have to travel further per day for resources. Adaptations for Bipedalism

Position of Foramen Magnum: Located more centrally under the skull, so that Spine Shape: Lower back the skull is balanced on the is reduced to produce an spine 'S' shape that has the effect of keeping the head and torso above the centre Femur: Longer and angled of gravity inwards from the hips so that the knees nearly touch. This “carrying angle” assists in Pelvis Shape: Short and positioning the upper body broad, for attachment of large, over the centre of gravity. powerful muscles for walking. Pelvis has become more 'bowl- shaped' to provide support for the organs of the torso.

Knee Joint: Bottom of the femur (knee joint) has a Shape of Foot: The anatomy of buttress of bone (called the the foot has changed to become lateral condyle). This stops a platform. Toes are short, with the sideways deflection of big toe forward thrusting. Inner thigh muscles during side of the foot is elevated into an walking. arch to provide shock absorption. Problems Hernias: The intestines may bulge out through our weakened abdominal wall. This is the result Caused by of our gut no longer being hung from the spine by a broad ligament as it is in quadrupeds; Bipedalism the problem is compounded by obesity. Slipped disc: Lower back Birth canal (in women): Changes in troubles, usually the result of pelvic shape in response to degenerative changes with bipedalism, together with babies born age, are compounded by the with larger skulls, cause childbirth load being carried by only two problems. limbs

Varicose Veins: An upright posture hampers venous return, allowing blood to collect in the leg veins. Blood must overcome about 1.2 m of gravitational pressure to return to the heart. Flat Feet: Feet may suffer strain because the body rests on just two limbs. The arches of the feet collapse resulting in flat footedness, distorted bones, hammer toes, and bunions. Trend #2: Hair Reduction

Hair Louse Retention of head hair: Hair on the head (and to a Soft Tick lesser extent the shoulders) reflects and radiates solar radiation (heat) before it reaches the skin.

Flea Thermoregulation: Shorter, finer hairs (not hair loss) in early hominids allowed Parasite control: greater heat loss by increasing Reduced body hair improves radiation from the skin surface. control of ectoparasites such as Well developed sweat glands fleas, ticks, and lice. allow us to lose heat at an -2 Particularly important when early astounding 700 watts m of hominids began to use a regular skin (a capacity not 'home base', as hatching approached by any other parasite eggs could reinfect mammal). them. Trend #3: Reduced sexual dimorphism

– On average, male gorillas and weigh about twice as much as females of their species. – In chimpanzees and bonobos, the size difference is much less, with males about 1.35 times heavier than females, on average.

• Sexual dimorphism in size is even more reduced in humans, with males averaging about 1.2 times the weight of females.

Trend #4: Decreasing relative size of face, jaw, teeth, esp. canines; increasing relative size of brain case, forehead – Large brains require more energy, more calories. Change in diet from mostly vegetarian to more omnivorous diets corresponds to the increase in brain size. – Eating meat increases supply of protein, fat and energy, making larger brain growth possible. – Hunting and killing prey on savannas is more difficult than gathering plant foods, so natural selection might have favored larger brains with greater intelligence.

Trend #5: Increase in brain size Reading: Food for Thought

Reading: What Makes Us Human Reading: What makes us different? D.3.8

Trend #6: Migration Out of Africa

The first modern humans appear in Europe 40 000 - Humans travel to 35 000 years ago the Americas between 30 000- 15 000 years ago Cro-Magnon 30 000 ya Earliest dating in East Asia is 67 000 years ago in southern China Skuhl 101 000 - 81 000 ya Qafzeh 120 000 - 92 000 ya

Probable area of Omo origin for modern Polynesia populated 195 000 ya humans some Malakunanja II progressively 4500 - 200 000 years ago 50 000 ya 700 years ago Lake Mungo Border Cave 31 000 ya 115 000 - 62 000 ya Klasies River Mouth 120 000 - 84 000 ya Australia was first occupied at least 50 000 years ago Statement D.3.5

The Origin of Modern Humans There are two theories accounting for the origin of anatomically modern humans:

Multi-regional Hypothesis Replacement Hypothesis (Out of Africa / Eve Hypotheses)

Present Modern Homo sapiens

Archaic Homo sapiens Extinction 0.5 mya Gene flow

Homo erectus

1.0 mya African origin African origin Multiregional Hypothesis

• Modern humans evolved in many parts of the world from regional descendants of H. erectus .

• In this view, the great genetic similarity of all modern people is the product of occasional interbreeding between neighboring populations that has provided corridors for gene flow throughout the geographic range of humans. Replacement Hypothesis

• All Homo sapiens throughout the world evolved from a second major migration out of Africa that occurred about 100,000 years ago.

• Modern humans replaced all the regional populations of H. erectus out of Africa about 1.5 million years earlier. The genetic data have mostly supported the replacement hypothesis.

Reading: Tangled Roots

Video: Journey of Man

Curtis

Gretel Uncertainties in Human Evolution • To become a fossil an organism needs to have hard parts, die and be buried in an anaerobic environment very quickly, and then be preserved through geological time, without being destroyed by tectonics or metamorphism, or removed by erosion. • These are pretty rare circumstances, so fossils are very rare. • It is hard to find complete fossils of hominid ancestors or find all the „missing links.‟ D.3.7

GENETIC VERSES CULTURAL EVOLUTION

Mousterian tools Jonzac, France GENETIC VERSES CULTURAL EVOLUTION

GENETIC CULTURAL • The product of natural • The product of learning. the selection transmission of acquired behavior characteristics • Innate, not modified • Learned during the life time during the organisms • Passed on to family, social life time group, population, within a • Passed on through generation and between hereditary information generations. • Fast change • Slow change Paleolithic Tools

Timeline of Stone Tool Technologies

Oldowan Mousterian Acheulian Upper Paleolithic First Appeared: First Appeared: First Appeared: First Appeared: 2.5 M yrs ago 150 000 yrs ago 1.5 M yrs ago 40 000 yrs ago “Driven by technological advances, humans are changing faster than ever. Coming soon: our next stage, Homo evolutus” The relative importance of genetic and cultural evolution for humans

• Cultural evolution is not limited to humans; examples found amongst birds and non-human

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

• This sets the possible scope of cultural evolution Observed evolution of cultures

• 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 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 Video: the Minds Big Bang

• Statements D.3.9 and D.3.10

Are we still evolving?

• Reading: what will become of homo sapiens