Early Hominins

primate brain case

small (~350 cc)

primate brow ridge

large and robust supraorbital torus

Sagittal crest

f

Occipital crest

f

primate canines

long

primate molars

large with heavy enamel

primate maxilla

prognathic

maxilla

Prognathic

lower or upper jaw protrudes beyond facial plane

primate dental arcade

V-shaped or parallel

zygomatic

primate zygomatic

robust

Foramen Magnum

opening in human skull used as primary passageway for the CNS

hominin taxon

all bipedal species

first bipedal primates

Africa

cladistic organization

organizes life forms based on shared derived traits

phylogenic organization

organizes life forms based on common ancestors

cladistic relationship

provides evidence of evolutionary relationships

phylogenic relationship

stipulates evolutionary relationships

cladistics

does not prove a time scale

phylogenics

includes a timescale

savannah hypothesis

increasing aridity in Africa shrank the
forests and forced early ancestors to savannah

aridity

permanent lack of moisture and precipitation

savannah hypothesis evidence

marine and soil analysis supports cooling/drying trend and isotope analysis supports expansion of grasslands

turnover pulse hypothesis

periods of climate change result in high rates of faunal turnover, generalists diversify

turnover pulse hypothesis evidence

high faunal turnover during glacial expansions

forest hypothesis

forested environments were the context in which human traits arose

forest hypothesis evidence

pollen analysis

obligate bipedalism

habitually walking upright

H1 of bipedalism origins

descended from an arboreal LCA

H2 of bipedalism origins

descended from terrestrial quadrupedal LCA

current evidence for earliest hominins

originated in forests and bipedalism became. more important as forestlands shrank

Sahelanthropus tchadensis date

6-7 mya

Sahelanthropus tchadensis brain

360 cc

Sahelanthropus tchadensis canines

larger canines than Homo, smaller than other NHP

Orrorin tugenensis date

6-5.7mya

Orrorin tugenensis area

Kenya

Orrorin tugenensis teeth

thick enamel, small cheek teeth, apelike canines

Ardipithecus ramidus date

4.4 mya

Ardipithecus ramidus area

Ethiopia

Ardipithecus ramidus brain size

300-350 cc

Ardipithecus ramidus ancestral trait

opposable hallux (big toe)

Ardipithecus ramidus derived traits

pelvis

root species for A. afarensis

Ardipithecus ramidus

Sahelanthropus tchadensis area

Chad

Australopithecus

varying degrees of arborealism and bipedality

Au. anamensis date

3.8-4.2 mya

Au. anamensis area

Kenya and Ethiopia

Au. anamensis brain size

370 cc

Au. anamensis teeth

large canines

Au. anamensis cheekbones

projected

Au. afarensis date

2.9-3.9 mya

Au. afarensis area

Tanzania, Kenya, and Ethiopia

Au. afarensis brain size

420 cc

Au. afarensis teeth

reduced canines, molars, prognathic face, strong chewing muscles

Au. afarensis importance

indirect evidence of pre-Oldwan stone tools

Au. garhi date

2.5 mya

Au. garhi area

Ethiopia

Au. garhi brain size

450 cc

Au. garhi importance

primitive stone tools

Au. africanus date

3.3-2.1 mya

Au. africanus brain size

400-500 cc

Au. africanus teeth

small canines, no diastema

Au. Sediba date

1.97 mya

Au. Sediba brain size

420-450 cc

Au. Sediba teeth

small

Paranthropus

adaptations to diet of hard or tough foods

Earliest stone age (ESA) technology

knapping

Lomekwian techno-complex

pre-homo and flake technology

Oldowan techno-complex

clear understanding of fracture mechanics