Transcript Australopithecus afarensis “Lucy & Luigi”

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
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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 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
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 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
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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-intoHabitual Biped
• 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"
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
Smallbrained,
bipedal
human
ancestors. The
benchmark by
which
anatomy of all
other early
hominid
s is
interpreted.
• 4 - 3 mya
• East Africa
• Fully bipedal
• Mix of human-like &
ape-like traits
• Forests, open
woodlands
• Sexually dimorphic
Lucy: 1st afarensis found
Her discovery revolutionized ways of thinking
about early hominids.
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Left to right: Lucy’s bones,
reconstructed Lucy, modern human
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)
A. afarensis skull morphology
Male
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Female
(Lucy)
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)
A. afarensis body morphology
Ground or tree-dweller?
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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
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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 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.
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
- 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:
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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
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
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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)
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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 erectus
Out of Africa
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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 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
?? 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 heidelbergensis
Ancestor to Neanderthals and Us
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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 heidelbergensis
First 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?): 350400 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 neanderthalensis
European descendants of H. heidelbergensis
Female
Eye, skin & hair
color speculative
Dark haired male
Young boy
Red-headed male
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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
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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
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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
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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
Neanderthal 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?)
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?
Recent genetic data
indicates no mixing
– 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
Anatomically modern Homo sapiens:
In Our Own Image
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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
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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
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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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