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

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

Alternative Hypothesis: TubersAlternative Hypothesis: Tubers

AbundantDigging sticks Nutritious if cookedSocial structure?

Did Did AustralopithecusAustralopithecus eat meat?�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

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

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?

Size, proportions and dimorphismSize, proportions and dimorphism

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!

Altering environmentExtending daily activitySocial focus

SafetyWarmthHunting & technology

Promethean FirePromethean Fire

Home base, anyone?Home base, anyone?

Glynn Isaac vs. Lew BinfordSite 50, 1.5 mya?Terra Amata, France 400 kya

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?

Conclusions:Conclusions:Hominid Package (“Sharing and Carrying”hypothesis) provides framework for research and debateCriticisms and alternative theoriesStill defended by some (Latimer, Lovejoy)Problematic for AustralopithecusMore probable for Homo, especially after 1 mya

NextNext……

The transition to sapiens