Ant Human Evolution Test #3 Set 2

Front 1

Earliest members of Homo
and
the traits that are used to include them in this genus and distinguish them from australopiths (4)

Back 1

1) Homo habilis
2) Homo rudolfensis
3) Homo ergaster

Traits:
1) inferred dexterity = skill in performing tasks → tools
2) smaller face and jaws
3) smaller teeth
4) encephalization

Front 2

Homo ergaster appears when and where

Back 2

1.8 mya - 600 kya
lower Pleistocene
Africa

Front 3

Cranial morphology of Homo ergaster
pleisomorphic 2
apomorphic 4
unique 2

Back 3

Pleisomorphic:
• postorbital constriction
• no forehead

Apomorphic:
• shorter, less prognathic face
• taller skull
• larger cranial capacity 500 - 1000 cc (still small)
• smaller jaws and posterior teeth

Unique:
• occipital torus
• large supraorbital torus
→ related to diet? for better adaption to tearing and biting?

Front 4

Postcranial morphology of Homo ergaster
4

Back 4

• long legs
• narrow hips and shoulders
• shorter arms
• barrel-shaped chest

→ fully committed to terrestrial life, first species with ability to run long-distances

Front 5

Factors behind increased height and cranial capacity in Homo ergaster fossils

Back 5

Change in climate impacted food supply → increased access to animal protein
→ led to physical and cerebral growth

Front 6

Homo ergaster and speech

Back 6

• Probably no spoken language
• size of vertebral canal in thoracic region is indicative of innervation of muscles and diaphragm
• H. ergaster's is smaller → less precise control over these muscles
→ lesser ability to control breathing associated with speech

Front 7

Homo ergaster and maturation

Back 7

rate of tooth enamel growth is indicative of rate of development
→ ergaster developed slower than australopiths, but faster than humans

Front 8

Homo ergaster and sexual dimorphism

Back 8

• reduced from ancestors, but more than humans
• males 20-30% larger than females

Front 9

Homo ergaster and circumstantial evidence for meat eating
3

Back 9

• hand axes good for butchering
• faunal remains with cutmarks
• H. ergaster teeth more suited for biting/tearing than for chewing

Front 10

Homo ergaster and direct evidence for meat eating
2

Back 10

• Hypervitaminosis A: Vitamin A poisoning from eating the liver of a large animal
• Terminal hosts for tapeworms: humans are terming hosts for 2 species of tapeworms, which diverged 1.7 - 0.8 mya, before animals were domesticated
→ therefore, our ancestors ate meat before this divergence

Front 11

First hominin to leave Africa and evidence of this

Back 11

Homo ergaster
• primitive forms of ergaster found at the Caucasus Mountains
• appear more like H. habilis and the australopiths
→ implies that ergaster left Africa early on

Front 12

Pleistocene environmental changes and impact on hominin evolution

Back 12

• There is a cooling trend, with variability in the middle
• glacial periods → expansive deserts → restricted migration limited east <-> west
• interglacial periods → returning forests → increased migration out of Africa into Asia north <-> south
• middle Pleistocene ergaster evolution towards modern humans
• new environments = variability of genes/gene flow (no longer isolated) = adaptations = evolution

Front 13

Homo ergaster vs. Homo erectus

Back 13

Ergaster → Africa
Erectus → Asia

• no difference in cranial capacity
• erectus less behaviorally flexible

Front 14

Homo erectus and tool use

Back 14

• associated with mode 1 tools
• mode 2 appears while there was an apparent meteor strike in Bose Basin, destroying the bamboo forest
• got rid of bamboo which they could have been making tools out of
• absence of bamboo created a need for new tools
• created open grasslands, in which hand axes may have been better suited
→ appearance of mode 2 tools
• mode 2 disappears when forest grew back