The Human Story Where We Came From How

The Human Story Where We Came From & How We Evolved

Identifying the first hominids • In L. C. A. , look for anatomical features shared by humans and living great apes • Starting from there, 1 st hominids must have evolved at least one feature that we see only in modern humans • Scientists focus on two major areas – Anatomy related to bipedalism – Size / shape of canine and 1 st premolar teeth 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

Placement of Foramen Magnum

Shape of Spine

Pelvic Girdle & Bicondylar Angle

Anatomical Adaptations for Habitual Upright Bipedalism A comparison of the chimp, human, and A. afarensis femurs demonstrates a rounder femoral head and longer femoral neck length in hominids.

Parallel Toes / Fixed Arches

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 Hominins The 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 Grabbing A Bite Keeping Cool Attracting Mates Weapons and Tools

Bipedalism: • Hauling Food As African landscape shifted from forests toward large patches of open woodlands & savannahs, food supplies waned, wannabe hominids descended from trees / became ground-dwellers. – Because could no longer feed where lived, were forced to carry food over long distances back to home bases - tricky task if remained quadrupeds. • While some contend early hominids gathered fruits and nuts, a few argue that they were scavengers. – Upright stance enabled ancestors to lug carcasses to safer areas for consumption, also allowing them to see other food sources or potential danger at greater distances

Bipedalism: A New World • As early hominids left forest to explore woodlands / savannas, no longer needed body structure for climbing. – Those who could walk upon two feet better able to survive • expended less energy / could travel longer distances than knucklewalkers • better able to see potential dangers lurking in the distance • Our ancestors developed an upright posture to – carry food over long distances – or find it.

Bipedalism: Attracting Mates • Sex — specifically males' desire to get more of it — a direct reason for why we walk upright. • Upright males better breadwinners – Those who could walk bipedally freed their arms to carry more food - made knuckle-walkers far less appealing to females. – Their ability to have more food for females (who remained at the home base to care for the offspring) ensured that they were able to reproduce, thus leading to future generations of adept bipeds who in turn were able to pass on their own genes.

Grabbing A Bite • Ability to walk upright was in part a serendipitous byproduct of new feeding habits. • As our ancestors descended from trees to forage on the ground for low-hanging fruits and berries, they began to feed from a squatting position. • Over time, physiological changes occurred in upper bodies, backbones, pelvic areas, causing weight and centers of balance to shift to a lower point in the body.

Bipedalism: Keeping Cool • Protected early hominids from overheating – Exposes less of body to direct sunlight on savannahs than quadrupeds of the same size (60% less heat load) • Raised bodies above the ground, enabling skin to come in better contact with cooler / faster-moving breezes – Also meant hominids needed only 3 pints of water / day, whereas quadrupeds needed 5

Bipedalism: ß Weapons & tools • Some hypothesize bipedalism brought forth our ability to use weapons / tools - others believe the reverse: advent of tool / weapon use encouraged us to become bipedal.

Six Major Hypotheses Hauling Food Grabbing A Bite A New World Keeping Cool Attracting Mates Weapons and Tools ALL these models may have played a role in the emergence of habitual upright bipedalism

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

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 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: 1/4 th 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 A species of bipedal apes • 5. 8 - 4. 4 m. y. a. • Possibly bipedal (but not like us) • Small bodied (64 -100 lbs); small brained (300350 cc) • Combo of hominid-like & chimp-like traits • Diet: unknown (relatively thin tooth enamel) • Well-watered, forested environment • Discovery Channel Website About "Ardi"

Ardi Revealed • Ardi’s skeleton includes many important bones of the skull, hands, feet, limbs, and pelvis. These fossil bones offer key insights into how 'Ardi' was built, and how she moved. Her skeleton demonstrates that she was capable of both walking upright AND clambering through trees with a grasping big toe, in a way unlike any other creature known to science. Ardi shows an unexpected mix of advanced characteristics and of primitive traits seen in much older apes that were unlike chimps or gorillas. As such, the skeleton offers a window on what the last common ancestor of humans and living apes might have been like. Interactive webpage: Ardi's Key Skeletal Features

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 Small-brained, bipedal human ancestors. They are the benchmark by which the anatomy of all other early hominid s is interpreted. • 4 - 3 mya • East Africa • Fully bipedal • Mix of human-like & ape-like traits • Sexually dimorphic

Lucy: 1 st afarensis found Her discovery revolutionized ways of thinking about early hominids. • • • Left to right: Lucy’s bones, reconstructed Lucy, modern human 1974 - Hadar, Ethiopia About 3’ 8” tall; 55 lbs Long arms / short legs Mid-20 s when died Teeth: small & unspecialized, indicating a mixed, omnivorous diet of mostly soft foods (fruits)

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

A. afarensis body morphology Ground 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

An afarensis 3 yr old baby girl • 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: 1/3 rd 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.

Australopithecus garhi: A stone tool using australopithecine? • Ethiopia • 2. 5 million years old • Mostly fragments of skulls, some post-cranial remains • Most intriguing: cut-marked animal bones found near garhi’s remains. Such marks are signs of stone tools being used to carve up animal carcasses. Can’t say for sure IF garhi was maker, maker-user, user (or none of these) of tools.

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

Australopithecine Foraging Behavior Foraging (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.

Major adaptive shifts in hominid evolution ca. 2 m. y. a. • Australopithecine lineage – 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 (Question: If one of the gracile australopithecine species is ancestral to Homo, how does one tell a late gracile australopith from an 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.

Earliest Members of the Genus Homo H. Habilis H. rudolfensis H. erectus* E. Africa 2 - 1. 5 mya 3 1/2 - 4’ tall East Africa 2 - 1. 8 mya 5 - 5 1/2 feet tall Brain: 510 cc (1 Brain: 775 cc (1 1/2 E. Africa 1. 8 - 1. 0 mya 5 1/2 - 6’ tall Brain: 800 -1200 cc *Sometimes called H. ergaster water bottle) water bottles)

Early Homo Behavior • Stone tools 1 st 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.

Out of Africa, Part One Homo erectus • • Found first in Africa = 1. 8 - 1. 0 m. y. a. Perhaps Rep. of Georgia = 1. 7 m. y. a. (H. georgicus? ) Island SE Asia = 1. 8 m. y. a. Continental Asia = 1. 4 m. y. a

Out of Africa, Part 2 • Homo erectus – By 1. 5 m. y. a develops a more sophisticated tool technology (Acheulian) – African forms sometimes called H. ergaster – Georgian forms sometimes called H. georgicus – Asian and southeast Asian forms always called H. erectus

H. ergaster vs. H. erectus H. georgicus H. ergaster East Africa / Georgia 1. 8 - 1. 0 mya Thinner cranial bones Less pronounced browridges H. erectus Asia 1. 8 -. 05 mya Thicker cranial bones More pronounced browridges

Homo erectus (Prometheus Unbound) • Invented new tool: handaxe – Larger tools, required more preparation than Oldowan choppers • First hominids to make tools to a predetermined shape • 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 • 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 and veggie consumption easier) Useful to lengthen the day into the night Keeps predators away Warmth

Homo erectus Why are these hominids so important? • ? ? FIRST TO LEAVE AFRICA ? ? • COMPETENT TOOLMAKERS: Acheulean – 1 st appeared 1. 5 m. y. a. – Shaping entire stone to stereotyped form – Bifacial flaking – Butcher animal carcasses / digging tools / cutting & scraping • FIRST to USE/CONTROL FIRE (ca. 1 m. y. a. ) • FIRST SYSTEMATIC HUNTING of medium -size game animals

Homo erectus Morphology • Body Size and Shape – Basically modern, but more muscled and robust – Some individuals very tall (boy from Nariokotome, Lake Turkana) = 6 feet tall when an adult üLarge brain: 700 - 1200 cc (overlaps moderns) üLong, low with receding forehead & large browridges üMidfacial pronathism / powerfully built jaw

Boy from Nariokotome Very 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 ? ? 1 st 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

Homo heidelbergensis Ancestor to Neanderthals and Us Name given to a range of specimens from about 800, 000 years ago to the appearance of Homo neanderthalensis in Europe and anatomically modern Homo sapiens in Africa

Homo heidelbergensis • 1 st appears ca. 1 mya - 800 k. y. a. - none later in time than 500 - 300 k. y. a. • Africa, Europe (but not Asia) • Brain larger than erectus: 12001500 cc • Skull more rounded, less robust but still with large brow ridges, receding foreheads & no chins

Homo heidelbergensis First BIG GAME hunters • By 500 k. y. a. using wooden spears to hunt large game • Bodybuilder physiques – Pronounced muscle markings – Thick layers of hard bone around central marrow cavities While heidelbergensis lived in Africa, other hominid species lived elsewhere: H. erectus continued successfully in eastern Asia and in Europe H. antecessor was living in Spain by 800, 000 years ago.

Homo neanderthalensis European descendants of H. heidelbergensis Female Dark haired male Young boy Red-headed male

N E A W N O D R E L R D T A L

Neanderthals: Ancestors Or Dead Ends? • Unique species that lived in Europe, southwest Asia, central Asia between 200, 000 0 30, 000 years ago (k. y. a. ) • Much controversy over their fate AND their 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

Neanderthals: Recent Views

Neanderthal Cranial Morphology

Neanderthal Cranial Morphology • Cranial cap: 1400 cc • Large midface / very big nose that projects forward • Large gap behind 3 rd molar • Large protruding occipital bone • Marked neck muscle attachments on skull • Very large incisor teeth • No chin • Double-arched brow ridge

Neanderthals & Modern Humans Compared Modern human child (left) and Neanderthal child (right) • Neanderthals differ from anatomically modern H. sapiens in a suite of cranial features: – low but elongated and broadened braincase – prominent brow ridges – Occipital bun – a depression on the surface of the occipital bone at the back of the skull – large face with rounded orbits, wide nasal aperture – mandible with a receding chin region – retromolar space in adult individuals

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

Us vs. Them

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)

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 Culture Settlements • Open sites, caves, rock-shelters • Built structures / windbreaks • Controlled use of fire: warmth

Neanderthal Social Behavior

Neandertal Cannibalism Ritualistic 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? )

Burying The Dead • Intentional human burials • Some graves contain offerings - stone tools, animal bones (flowers? ) • Reasons for burial?

The Fate of the Neanderthals: Part I By 30 k. y. a. no more Neanderthals. Why? • 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 • • Died due to diseases brought by anatomically modern H. sapiens? Genetically absorbed into anatomically modern H. sapiens populations 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 rockshelter 25, 000 to 24, 500 years ago Czech Republic, male, mixture of Neanderthal and a. m. Homo sapiens features Recent genetic data indicates no admixture

In Our Own Image • • Idaltu: Ethiopia / 160, 000 y. a. Cro-Magnon: Europe / 45, 000 y. a.

Early Anatomically Modern H. sapiens Defined Morphologically, Not Behaviorally • • Tall, almost vertical forehead Smallest teeth (relative to body size) of all the hominids) Small to minimal brow ridges No retromolar gap (we get impacted wisdom teeth) Cranial cap. : 1350 (1000 - 2000) There is a chin, a uniquely modern human trait High rounded cranium : widest point on sides of parietals

Complexity of Culture Begins about 50 k. y. a. • • Blade tools: increased technological abilities Atlatl Small bone & ivory tools Fishhooks Tailored skin clothing Bow and arrow Nets, snares Expansion into new eco-niches – Especially plant foods / marine foods • • • Ubiquitous burial of the dead Postmortem modification common Art and symbolism

Spreading Out

Art Cave paintings and “venus” figurines

Origins of Moderns • Lots of debate • Several major theories – Recent African origin – Multiregional origins – Multiple dispersal origins

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