The Human Story

Where We Came From

&

How We Evolved

There is no straight line in the greater than four million-year-old journey of the

family called HOMINIDAE.

From Ape to Hominid

• Proto-Hominids (Opportunistic bipeds)– Sahelanthropus tchandensis / Orrorin tugeninsis

• Transitional Opportunistic-into-Habitual Bipeds– Ardipithecus ramidus / Australopithecus anamensis

• First True Habitual Upright Bipeds– Australopithecus afarensis / A. africanus / A. garhi– Australopithecus robustus / A. boisei

Identifying the first hominids• In L.C.A., look for anatomical features shared

by humans and living great apes

• Starting from there, 1st hominids must have evolved at least one feature that we see only in modern humans

• Scientists focus on– Anatomy related to bipedalism

Large brain size, hard evidence for culture, language, etc., come much later.

Evidence of Bipedalism

• Placement of foramen magnum• Shape of spine• Shape of pelvic girdle• Bicondylar angle (knock-kneed)• Parallel toes (no divergent big toe)• Two fixed arches in foot

– Side to side / front to back

ORIGINS OF BIPEDALISM

Or

WHY WE WALK ON TWO LEGS

Download and read these articles:The Origins of Habitual Upright Bipedalism

The Origins of Obligate Bipedalism in HomininsThe Whats and Whys of Habitual Upright Bipedalism

If you asked a roomful of anthropologists why we walk on two legs - not get the same answer from any two of them.

Specialists cite everything from changing landscapes to needing to keep cool to heightening sexual attraction - generally agreeing only on one point: that everyone else's hypothesis is wrong.

Let’s take a look at some of these hypotheses.

Six Major Hypotheses

Hauling Food

A New World

Attracting Mates

Grabbing A Bite

Keeping Cool

Weapons and Tools

ALL these models may have played a role in the emergence ofhabitual upright bipedalism

From Ape to Hominid

• Proto-Hominids (Opportunistic bipeds)– Sahelanthropus techandensis / Orrorin tugeninsis

• Transitional Opportunistic-into-Habitual Bipeds– Ardipithecus ramidus / Australopithecus anamensis

• First True Habitual Bipeds– Australopithecus afarensis / A. africanus / A. garhi– Australopithecus robustus / A. boisei

Proto-Hominids

• Molecular biology strongly suggests:– Last common ancestor of chimps & humans

lived 5-8 m.y.a.

• Two recent finds warrant our attention:– Sahelanthropus tchadensis– Orrorin tugenensis

Sahelanthropus tchadensis• 6 - 7 m.y.a.• Brain size: 1/4th of ours• No post-cranial bones• Don’t know if habitual biped• Lived in variety of habitats• Likely ate mainly fruit, with

smaller amounts of other foods.

Download and read:The Earliest Possible Hominids

Orrorin tugenensis• 6 m.y.a.• Remains fragmentary• Canines / premolars

extremely ape-like BUT with thick tooth enamel (like hominids)

• Maybe bipedal• Inferior side of femoral

neck (#1 on picture) is thick (like hominids)

Ardipithecus ramidus Transitional Opportunistic-

into-Habitual Biped

• 5.8 - 4.4 m.y.a.• Possibly bipedal (but not like us)• Small bodied (64-100 lbs); small brained (300-

350 cc)• Combo of hominid-like & chimp-like traits

• Diet: unknown (relatively thin tooth enamel)• Well-watered, forested environment• Discovery Channel Website About "Ardi"

Australopithecus anamensis

• 4.2 - 3.9 m.y.a.• Fragmentary remains• Teeth and jaws similar to

fossil apes• May be earliest

incontrovertible evidence of bipedalism

• Strongly resembles Austr. afarensis

• Streamside forests

Australopithecus afarensis

• 4 - 3 mya

• East Africa

• Fully bipedal

• Mix of human-like & ape-like traits

• Forests, open woodlands

• Sexually dimorphic

Small-brained, bipedal human ancestors. The benchmark by which anatomy of all other early hominids is interpreted.

Lucy: 1st afarensis foundHer discovery revolutionized ways of thinking

about early hominids.

• Hadar, Ethiopia• About 3’8” tall; 55 lbs• Long arms / short legs• Mid-20s when died• Teeth: small &

unspecialized, indicating a mixed, omnivorous diet of mostly soft foods (fruits)

Left to right: Lucy’s bones, reconstructed Lucy, modern human

A. afarensis skull morphology

• Cranial capacity: 350 -500 cc (2/3rds - 1 water bottle• Small sagittal crest in males• Slightly projecting upper canine teeth in males• Parallel rows of cheek teeth (like apes)

Male Female (Lucy)

A. afarensis body morphologyGround or tree-dweller?• Slightly curved hand & foot bones• Relatively long and powerful arms• Bowl-shaped pelvis• Knock-kneed (knee joint angled

inward)• Heel bone heavily built (like ours)• Foot may have had high, fixed arches (Laetoli?)

A. afarensis footprints

• Laetoli, Tanzania: home to a footprint trail 3.5 m.y. old

• Probably a trackway of A. afarensis

Selam: 3 yr old baby girl Au. afarensis

• Ethiopia (Hadar) • Lived 3.3 m.y.ago• Ape-like scapula• Human-like knees• Finger bones partially curved• Heel bone well-developed• Endocast shows delayed brain growth (like us)• Chimp-like hyoid bone

Australopithecus africanus• 3.5 - 2.0 m.y.a.• Mainly S. Africa• Mixture of habitats• Fruit, salads, insects, small

easily captured prey• Brain size: 1/3rd ours• Relationship to other hominids?

Unknown

This species slightly different from A. afarensis: slightly taller, less facial prognathism, slightly larger brain. Also lived in drier habitats (especially dry scrublands and perhaps open grasslands), and thus may have exploited different resources.

Australopithecine Foraging BehaviorForaging (the systematic search for food and other provisions) was THE lifeway of all hominids from the earliest australopithecines until about 10,000 years ago (the start of agricultural modes of subsistence.

Foraging by australopithecines and early species of Homo most likely consisted of collecting roots, berries, seeds, nuts, salad greens, insects, etc. Around 2 m.y.a meat, obtained by scavenging, became part of the foraging way of life. Eventually fish and shellfish would be added.

The Robust AustralopithecinesDietary specialists?

• One of most fascinating branches of human family tree

• Reveal radically different way of being hominid

• About 2.5 m.y.a they diverged from our own lineage - existed down to about 1 m.y.a.

• Came to be defined by an adaptation to eating hard foods like nuts, seeds, and roots

Robust Austraopithecine Morphology

• 2.5 - 1 m.y.a.• South and East Africa• 3 species - united by suite of

features related to eating tough foods:– Extremely large molars / premolars– Dished face– Extremely large chewing muscles– Wide-flaring cheekbones– Pronounced pinching-in behind the

eye orbits– Prominent sagittal crest

Robust australopithecine behavior

• Omnivores, but relied on hard to chew foods (nuts, roots, seeds)

• Probably used tools (bones/horns showing polishing, maybe used for digging up roots)

• Lived in (open) woodlands and savannas • Evolutionary dead end

Digging sticks used by modern chimpanzees. While such tools have not been found with robust australopithecine fossils, it is possible they used such tools

Major adaptive shifts in hominid evolution ca. 2 m.y.a.

• Australopithecine lineage– Gracile lines become extinct– Robust lines see an intensification of adaptation to hard

object feeding

• Emergence of Homo lineage– Several new species appear on African landscape– Physically / behaviorally different from earlier &

contemporary australopithecines• Flatter faces• Brain reorganized (lateralization & language regions)• Unquestioned manufacture/use of stone tools (bone/horn/wood?)• Added meat to diet (scavenging)• Some species have brains as large as 750 cc

Earliest Homo species

• Contentiousness regarding who belongs to early Homo

• At least 3 (perhaps more) Homo species– Homo habilis = 2 - 1.5 m.y.a– Homo rudolfensis = 2 - 1.8 m.y.a– Homo erectus (aka H. ergaster) = 1.8 - 1.0 m.y.a.

Early Homo Behavior• Stone tools 1st appear ca. 2.5 mya

– Most often attributed to H. habilis ( maybe A. garhi)

– Earliest tools (Oldowan tradition)• Flakes (cutting/scraping)

• Chopper / chopping tools (“smashers / bashers”)

• Hammerstones

• Some bone/horn w/scratches (digging?)

• Meat eating takes on increasing importance after 2.5 m.y.a.

• Several types of sites: quarries, food processing locations

Making / Using Oldowan Tools

Hominids often traveled up to 10 km to acquire right kind of stone from which to make tools.

Early Homo Scavenging Behavior

Can a hominid eat meat obtained like this and not get sick? Perhaps if one gets there within a few hours of a predator’s kill.

Homo erectusOut of Africa

• Earliest in Africa = 1.8 (H. ergaster)

• Island SE Asia = 1.7 m.y.a.

• Continental Asia = 1.4 m.y.a

• Rep. of Georgia = 1.7 m.y.a. (H. georgicus?)• Spain = 800,000 y.a. (H. antecessor?)• Flores = 90,000 y.a. (H. floresiensis?)

Homo erectus(Prometheus Unbound)

• First hominids to make tools to a predetermined shape• Cognitive mapping of raw material (recognize potential flaws)• Invented new tool: handaxe

– Larger tools, required more prep than H. habilis choppers

• First hominids to make task-specific tools– Some tools used for butchering animal carcasses; others for working

with wood; still others for use with veggies

• First hominids to hunt small to medium size game• Probably the first hominids to use, perhaps even control, fire

– Hints of use at South African site between 1.5 - 1.0 m.y.a.– Fire allows cooking foods (makes meat & veggie consumption easier;

lengthen day into the night; keeps predators away; warmth

Homo erectus Morphology

• Body Size and Shape

– Basically modern, but more muscled and robust

– Some individuals very tall (boy from Lake Turkana) = 6 feet tall when an adult

Large brain: 800 - 1200 cc (overlaps moderns at upper end)

Long, low with receding forehead & large browridges

Midfacial pronathism / powerfully built jaw

Boy from NariokotomeVery tall hominid at 1.5 mya

• About 8 years old when he died• 5’ tall (6 feet @ maturity)• Legs relatively long in proportion to body

as compared to earlier hominids• Well adapted to staying cool in hot, dry

climates• Face, molar teeth, chewing muscles smaller

than earlier hominids (softer, high-quality - perhaps cooked - foods)

• Skull-to-pelvis proportions of females: give birth to relatively immature infants– Implications: long infancy-childhood

dependency period: good for learning

Homo georgicus?? 1st Hominid to Leave Africa ??

• Dmanisi, Georgia (Caucasus Mtns)

• 1.7 - 1.8 m.y.a.• Late H. habilis or early H. erectus• Brain size: 600-750 cc• Stature: 1.5 m• Oldowan tool technology

THE RISE OF MODERN HUMANS

From

Homo erectus

To

Homo sapiens

Via

Homo heidelbergensis

The Invasion of Europe• Earliest occupation poorly understood

• Sima del Elefante, Atapuerca, Spain– 1 million years ago

– Primitive stone tools

– Animal bones with cut marks

• Gran Dolina, Atapuerca, Spain– 800,000 yrs ago

– 6 hominids: share many physical similarities with Homo erectus

• May represent link between H. erectus and H. heidelbergensis

• Often given the name Homo antecessor

All hominid remains exhibit evidence of butchering (cutmarks, dismembering, skinning defleshing)

– Oldest evidence of human cannibalism

Homo heidelbergensisAncestor to Neanderthals and Us

• 500,000 to 300,000 years ago• Africa, Europe (none in Asia)• Brain larger than erectus• Skull more rounded, less robust but

still with large brow ridges, receding foreheads & no chins

H. erectus

H. heidelbergensis

Homo heidelbergensisFirst BIG GAME hunters

• By 500 k.y.a. = wooden spears used to hunt large game (rhinos, horses, hippos, giant elk)– Cut marks lie UNDERNEATH

toothmarks

• Ground minerals to produce pigments (body painting?): 350-400 kya

NOTE: While heidelbergensis lived in Africa, other hominid species lived elsewhere: H. erectus continued successfully in eastern and southeastern Asia

La Sima de los Huesos (The Pit of Bones)A most important H. heidelbergensis site

• 400,000 y.a.• 32 individuals• Bodybuilder physiques

– Pronounced muscle markings

– Thick layers of hard bone around central marrow cavities

• Not a living site– Burial? / Washed in?

“One handaxe does not a ritual make.” - crsmith

Homo neanderthalensisEuropean descendants of H. heidelbergensis

Female

Red-headed maleYoung boy

Dark haired male

Eye, skin & hair color speculative

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T

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L

D

Neanderthals: Ancestors Or Dead Ends?

• Europe, southwest Asia, central Asia between 200,000 - 30,000 years ago

• Much controversy over – their fate

– relationship to anatomically modern humans (H. sapiens) No other aspect of human

evolution has generated as much public interest for so long a time as the story of the Neanderthals.

Neanderthals: Earlier Views

Until very recently, Neanderthals were most often depicted as brutish, dimwitted, “half man . . . half beast.”

Neanderthals: Recent Views

Neanderthal Cranial Morphology

• Cranial cap: 1400 cc

• Large midface / large nasal appeture / very big nose that projects forward

• Large gap behind 3rd molar

• Large protruding occipital bone

• Marked neck muscle attachments on skull

• Very large incisor teeth

• No chin

• Double-arched brow ridge

A Comparison: Side by Side With A Relative

• Brain case: low vs. high• Nasal opening: large vs. narrow• Collarbone: long vs. shorter• Rib cage: conical vs. cylindrical• Limb bones: thick-walled vs.

thin-walled• Hand bones: robust vs. slender• Trunk: short vs. long• Hips: flaring vs. narrow• Joint surfaces: large vs. smaller• Lower leg: shorter vs. longer• Bowed limbs vs. straight limbs

Explanation for Neanderthal Morphology

• Cold weather & harsh climate adaptations

• Strenuous hunting

Neanderthal culture

Neanderthal Culture: Stone tools

• Mousterian toolkit– Effective but simple – Changed little over 100,000 yrs.– Trimmed flint nodules

• Strike-off lots of flakes – predetermined form -

retouched)– Tool specialization

• Skin & meat preparation• Hunting• Woodworking• Hafting

– Some wooden tools (including thrusting spears) tipped with stone points

Levallois Flint Knapping

• Careful retouching of flakes taken off cores

• Specific uses of flakes– Animal butchering

– Woodworking

– Bone & antler carving

– Working of animal hides

Neanderthal Culture: Subsistence

• Extremely successful hunters– Jabbing spears (not thrown) w/ hafted stone points– No long-distance hunting (locally available game)

• Cave bear, Deer, Woolly rhinoceros, mammoth, wild cattle, reindeer, horse, wild ass, ibex, saiga

– Neanderthal skeletons often show fractures• Fairly efficient gatherers

– Berries, greens, roots - limited time frame (few weeks)

Neanderthal CultureSettlements

• Open sites, caves, rock-shelters• Built structures / windbreaks

• Controlled use of fire: warmth

Neanderthal Social Behavior

Neanderthal CannibalismRitualistic or Nutritional Purposes

• Possible evidence– France & Croatia

– Fragmentary bones show stone-tool cut marks similar to those found on butchered game animals

– Some long bones smashed to get marrow

Burying the Dead• Intentional • Some grave offerings: stone tools, animal bones

(flowers?)

Neanderthals’s Fate: Part I

By 30,000: Neanderthals gone• Sudden climatic change

– Large game dying out and Neanderthals hunting methods not suitable?

• Out competed by anatomically modern H. sapiens?– Better energy extraction methods

– Shorter gestation periods

• Diseases brought by a.m. H. sapiens?

• Genetically absorbed into .am. H. sapiens without significant genetic contributions to modern populations?

The Fate of the Neanderthals: Part II

• Interbred with anatomically modern H. sapiens to produce modern Europeans?– Four-year-old child buried in a Portuguese

rock-shelter 25,000 to 24,500 years ago– Czech Republic, male, mixture of

Neanderthal and a.m. H. sapiens features

Recent genetic data indicates no mixing

Anatomically modern Homo sapiens:In Our Own Image

• Descendants of African H. heidelbergensis

• First appear about 200,000

• Defined morphologically, not behaviorally

• Tall, almost vertical forehead

• Small to minimal brow ridges

• No retromolar gap (thus impacted wisdom teeth)

• Cranial cap.: 1350 (1000 - 2000)

• Pointed chin (uniquely modern trait)

• High rounded cranium : widest point on sides of parietals

A Time of Crisis: 140,000 years ago

• Mega-drought– Much of African environment becomes desert -

desert-like– Dramatic reduction of hominid pops. (600 - 1200

breeding individuals) – Hominids forced into refuge areas (principally:

south African coastline)– Began to exploit new resources (shellfish, penguins,

also hunting/gathering on coastal plains) reflects a new versatility

Refuge Sites

• Pinnacle Point, So. Africa (140 - 70 kya)– Earliest tools made from beach cobbles; later tools made

from stone quarried 20+ km away, then heat treated– Some of earliest evidence H. sapiens living off sea (cooked

shellfish) = 70,000 years ago

• Klasies River Caves, So. Africa (130 - 60 kya)– 130-119 kya: systematic use of marine resources: ate

shellfish, seals, penguins, hunted antelope, gathered plant foods (roasted in hearths built for the purpose)

– Fire-blackened fragments of human skulls / other bones showing cut marks = Cannibalism

Complexity of Culture

• Blade tools: increased technological abilities• Spearthrower (lightweight spears)• Small bone & ivory tools• Fishhooks• Tailored skin clothing• Expansion into new eco-niches• Ubiquitous burial of the dead• Postmortem modification common• Art and symbolism

– Cave paintings– Portable art (beads/ carved bone - stone - wood)

Symbolism & Art

Geometric figures: 95 kya

Shell beads: 70 kya

Cave paintings: 30 kya

Earliest musical instruments: 35 kya

“Venus” figurines: 35 kya

Leaving Home

• 95 kya: SW Asia– Burial of mother/child

• Europe: 46 kya• SE Asia: 60 kya• Asia: 40 kya• Australia: 60 kya• Americas: 15-20 kya

Why do modern humans have different skin colors? It may all

come down to VITAMINS

Only Skin Deep• Skin color variations are adaptive traits that

correlate closely to geography and the sun’s ultraviolet radiation, not race.

• Skin pigmentation developed as body’s way of balancing its need for vitamin D and folic acid.

– Vitamin D (calcium absorption for healthy bones)– Folic acid (healthy fetuses)

• Populations closer to the equator have darker skin to prevent: – folate deficiency – too much Vitamin D production

We are more alike my friends than unalike. - Maya Angelou

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