Upload
others
View
6
Download
0
Embed Size (px)
Citation preview
Cranial Morphology of Cranial Morphology of Homo erectusHomo erectusAlveolar prognathismLarger teeth than modernsSupraorbital torusLow foreheadPostorbital constrictionOccipital bunThick cranial bonesNo chinCranial capacity: 800-1100 cc (gradual increase)
The career of The career of Homo erectusHomo erectusAfrica 1.9 myaChina and Java 1.6 myaEurope after 1 myaJava, 35,000 years?Acheulean tools after 1.5 mya, fire after 1.3 mya
Meat + high-end plant foods
Mainly vegetarian diet, little processing
Brain size much larger than apes
Brain size close to apes
Stone toolsFew if any stone tools
Genus HomoGenus Australopithecus
If I Only Had a Brain . . .If I Only Had a Brain . . .
What does it take?
Staying coolStaying cool
PROBLEM:Most mammals cannot remain active in tropical daytime Brain cooling presents extra challenge
SOLUTIONS:Global cooling at time of Homo emergenceTriple benefit of bipedal postureSweat on hairless body 250 times more effectiveAltered arrangement of blood vessels cooling brain
Energy needs of Energy needs of an expanding brainan expanding brain
20% energy for 2% of body massGut vs. brain– Both expensive– Mutually exclusive
Reducing gut size– Depends on diet
Meat?
Meat and the BrainMeat and the Brain
Homo brain grows at fetal rate after birthEnergetics of nursing– Baby higher on food
chain – 10:1 efficiency drop
Maternal nutritionSignificance of meat
HighHigh--Payoff Plant FoodsPayoff Plant Foods
Roots– Abundant– Digging sticks – Nutritious if cooked
Nuts, etc.Skills, processing
(Did (Did gracile gracile AustralopithecusAustralopithecusever eat meat?�)ever eat meat?�)
Stable isotope analysis of South Africanafricanus fossils indicate C4 plants– Meat from grazing animals?
A. garhi from Ethiopia: tools and cut bones
KNM-ER 1808Homo erectus/ergaster
Leakey team, 1974East Lake Turkana, KenyaAge: 1.7 million years
Partial female skeleton displays pathological bone buildup, suggesting hypervitaminosisfrom eating carnivore liver. She must have been cared for during her long terminal illness.
Normalerectus
1808tibia
Hunters or Hunters or Scavengers?Scavengers?
Many species do bothWhat kind of scavenging?– Marginal scrounging?– Power scavenging?
Hunters or Scavengers?Hunters or Scavengers?Many species do bothWhat kind of scavenging?– Marginal scrounging?– Power scavenging?– Blumenschine’s non-
confrontational scavengingLouis Leakey– Experiments in low-tech
hunting– Traps and snares
“Mighty hunters” or opportunists?– rudolphensis and early
erectus likely opportunists– Later erectus a “mighty”
hunter?
Torralba Torralba andand AmbronaAmbrona
Late Homo erectus400,000 years ago
Males relatively less competitive
Males competitive
Males related; stay in group
Males in group unrelated; leave group at time of sexual maturity
Sex dimorphism 10-20%Sex dimorphism 100%
Genus HomoGenus Australopithecus
Humanlike body shape and fully dedicated bipedalism
Bipedalism + arboreal capability; intermediate body shape
Humerofemural index 70-75%
Humerofemural index 85-95%
Genus HomoGenus Australopithecus
Size, proportions and dimorphismSize, proportions and dimorphism
Kamoya Kimeu, Leakey team, 1984West Lake Turkana, KenyaAge: 1.6 million yearsCranial capacity: 880 cc
The Turkana boy is the most complete of any early skeleton, and it has enabled scientists to learn much about Homo erectus/ergaster. It died in early adolescence but would have reached a height of more than 6’ at maturity, with a cranial capacity of 909 cc.
KNM-WT 15000Nariokotome or “Turkana boy”
Homo erectus/ergaster
Turkana Turkana BoyBoy vsvs. Lucy. Lucy
Rib cage?Body shape?Pelvic shape?Waist (gut)?Tibia & ulna?
The Great LifeThe Great Life--History ShiftHistory ShiftLife History: Gestation, birth, weaning, developmental patterns, sexual career, life span, etc.Leakey: major shift in HomoEvidence: Dental growth rates, pelvic and skull measurementsAustralopithecus had short, chimplike childhoodHomo pattern:– Slow body growth, fast brain growth– Adolescent growth spurt
Brain growth from birth to adulthood:Ape 2xAustralopithecus 2.6xHomo erectus 3.3xHomo sapiens 3.5x
“Human grade” life history: long childhood, adolescent growth spurt, prolonged life span
“Ape grade” life history (age of weaning, sexual maturity, life span, etc.)
Humanlike dental growth pattern
Apelike dental growth pattern
Tripling of brain size from birth to adulthood
Doubling of brain size from birth to adulthood
Gestation period less than half that predicted by general primate pattern
Gestation period correlates with brain size as in other primates
Genus HomoGenus Australopithecus
Diet, Niche, & Life History
A Theory of Human Life History Evolution: Diet, Intelligence, and Longevity
Hillard Kaplan, Kim Hill, Jane Lancaster, A. Magdalena Hurtado, University of New Mexico
Evolutionary Anthropology, 9:4 (2000) pp. 156-184
• Relies heavily on hunter-gatherer studies
• Inter-species comparisons• Life history theory• Human capital theory
• Compatible with Lovejoy, Leakey• More remains to be done: Vague on
evolutionary timing, species• Much can be added in terms of culture
and language
The Theory
• Begins with ecological premises--the human adaptive niche (presumably from early Homo times if not before)
Human Niche
• “Humans are specialists in that they consume only the highest-quality plant and animal resources in their local ecology and rely on creative, skill-intensive techniques to exploit them.”
• Allows them “to colonize all of earth’s terrestrial and coastal ecosystems.”
Dietary Niches
Food Types• Collected
– Leaves, fruits, insects• Extracted
– Nuts, termites, tubers• Hunted
– Small game, birds, etc– Large game
• [Major scavenging?]
Learning and productivity
Life History Trends• Investment in skills• Long childhood
– Slow body growth– Rapid brain growth
• Adolescent growth spurt• Extended life span
– 2x chimpanzee – Post-reproductive women– Contribution to food supply– Labor and skills– Cultural “capital”
Lower Mortality:Part of Extended Life Span
• Group size• Food package size• Food sharing• Hunting skills and tools• Knowledge of animal behavior
Food exchange
• Male to female• Three generational flow, old to young• Support of reproduction• [Pair bonding and CSR?]
Flow Chart
Brain, intelligence, language
• Selective pressure for…• Conditions for…• [Role of home base?]
Language: gestures, mimesis, invented lexicon (eventually, syntax)
Apelike call systems
Increasing basicranial flexionApelike vocal tract; flat basicranium
Increasingly abstract thought (narrative binding)
Apelike intelligence
Food sharing, economic exchange, provisioning
Hand-to-mouth food consumption
Continuous sexual receptivity and pair-bonding
Estrus, visual and olfactory sexual cues
Home baseLack of home base
Genus HomoGenus Australopithecus
Example: Example: FLKFLK--Zinj Zinj ““living floorliving floor””Olduvai Gorge, Mary LeakeyZinj skull found thereThousands of mammals bones– Open-country species– Cut marks & tooth marks
Homo tibiaOnce near a lakeOldowan toolsManuports
Theories of Site FormationTheories of Site FormationHome base?Animal activity?Water action?Routed foraging?Picnic site?Tool cache?Kill site?Scavenged carcass?Palimpsest?
Home base, anyone?Home base, anyone?
Glynn Isaac vs. Lew BinfordSite 50, 1.5 mya?Terra Amata, France 400 kya
Altering environmentExtending daily activitySocial focus
SafetyWarmthHunting & technology
Promethean FirePromethean Fire
Language: gestures, mimesis, invented lexicon (eventually, syntax)
Apelike call systems
Increasing basicranial flexionApelike vocal tract; flat basicranium
Increasingly abstract thought (narrative binding)
Apelike intelligence
Food sharing, economic exchange, provisioning
Hand-to-mouth food consumption
Continuous sexual receptivity and pair-bonding
Estrus, visual and olfactory sexual cues
Home baseLack of home base
Genus HomoGenus Australopithecus
Who talked?Who talked?Contours of skull, neckReconstructed Australopithecusvocal tract is apelike– Could not make human speech sounds– High larynx
Human larynx is low– Flexed basicranium
erectus was transitionalTurkana boy’s vertebra had small spinal foramen– Limited ability to control muscles for
speech
proto-language?(more later . . .)
Fire and speechFire and speech
Larynx descends in Homo, for speechSusceptibility to chokingMeat is a common culpritMeat is important for brain growthCooked meat easier to swallow
Viva Prometheus!
Transitional Homo: Transitional Homo: The Late The Late ErectinesErectines
The Awkward Age . . .The Awkward Age . . .At 1At 1 myamya, erectus, erectusAt 100At 100 kyakya, modern sapiens, modern sapiensThe The inin--betweenersbetweeners::–– Cranial/facial morphology resembles Cranial/facial morphology resembles
erectuserectus–– Growing cranial capacity: 1100Growing cranial capacity: 1100--1300 cc1300 ccWhat to call them?What to call them?
Proposed namesProposed names
EACH HAS ITS PROBLEMS . . .EACH HAS ITS PROBLEMS . . .““Late Late Homo erectusHomo erectus””““Archaic Archaic Homo sapiensHomo sapiens””““HomoHomo heidelbergensisheidelbergensis””–– Diverse within, and fuzzy at the edgesDiverse within, and fuzzy at the edges–– Adds another name to rememberAdds another name to remember–– But gaining favorBut gaining favor
HomoHomo heidelbergensisheidelbergensis
A A HomoHomo heidelbergensisheidelbergensis SamplerSampler
SteinheimSteinheim, Germany, Germany250250 kyakya 1200 cc1200 cc PetralonaPetralona, Greece, Greece
300300--400400 kyakya 1220 cc1220 cc
BodoBodo, Ethiopia, Ethiopia600600 kyakya
KabweKabwe (Broken Hill), (Broken Hill), ZambiaZambia
300300 kyakya 1300 cc1300 cc
AtapuercaAtapuerca, Spain, Spain300300 kyakya 1125 cc1125 cc
AragoArago, France, France400400 kyakya 1166 cc1166 cc
MauerMauer, Germany (Type Specimen), Germany (Type Specimen)400400 kyakya
BoxgroveBoxgrove, England, England500 500 kyakyaHomo Homo heidelbergensisheidelbergensis??Rugged tibia,Rugged tibia, AcheuleanAcheulean tools, tools, evidence of big game huntingevidence of big game huntingSimilar 4Similar 4--500500 kyky old Europeanold Europeanacheuleanacheulean sites :sites :–– TorralbaTorralba--AmbronaAmbrona–– TerraTerra AmataAmata–– St.St. AcheulAcheul (Knox(Knox handaxeshandaxes))
The Family Blob
Homo erectus
H. heidelbergensis
H. sapiensNeanderthals
SpeciationSpeciationSpeciation