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Palaeoanthropology > H. ergaster and H. erectus > Flashcards

H. ergaster and H. erectus Flashcards

1
Q

What is important about H. erectus s.l.?

A
  1. Conforms to criteria expected in Homo
    - Obligate, modern biped
    - Big brain, relatively large cranial capacity
    - Small teeth
  2. First hominin that is more closely related to modern humans, both cladistically and in terms of adaptions
  3. First hominin to leave Africa?
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2
Q

Oldest H. erectus specimens

A

KNM-ER 2598 - Kenya, 1.9mya
KNM-ER 3733 - Kenya, 1.6-1.8mya
Dmanisi sample - Georgia, 1.8mya
Sangiran fossils - Java, 1.8mya

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3
Q

Youngest H. erectus specimens

A

Ngandong and Sambungmacan - Java, 30-40,000 years ago

Suprisingly young - H. sapiens already living in Asia

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4
Q

H. erectus vs H. habilis

A 
Longer and lower braincase
Marked sagittal keel
Bigger brain
Less prognathic
Strong supraorbital torus
Strong occipital torus
Smaller dental size
Thicker cranial bones
Pentagonal in rear view
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5
Q

H. erectus morphology and trends

A 
Classic H. erectus:
Sagittal keel
Double-arched supraorbital torus
Large, pneumatised face
Long braincase
Angled occipital bone
Occipital torus

H. erectus s.l.:
Reduction in size of posterior teeth
Increased body size and modern human-like limb proportions
Absolute brain size increase
Association with Oldowan and Acheulean stone tools
Wide geographic distribution outside Africa

Anatomical traits indiicative of modern bipedalism
Body size adapted for distance travel and competition with other carnivores
Brain and body size enter the range of variation observed in modern humans - 40-75kg, 150-185cm, 700-1100cc

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6
Q

Endurance running

A

Morphology of H. erectus shows selection for bipedal running, not walking
Adaption to running at expense of adaptions to arboreality at 2mya.

Bipedalism very efficient for running long distance
Not good sprinters but can outrun most species over long distances -> chase animals until they die from exhaustion. Hunting without sophisticated tools

Mechanisms of dissipating heat - sweating, hairlessness

Important for hominin dispersal?

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7
Q

H. ergaster vs. H. erectus

A

H. ergaster - Africa, 1.9-1.0mya
H. erectus - Asia, 1.8mya-30kya

H. erectus (Sangiran 17) has sagittal keel, parasagittal depression, thick browridge, long/flat/low braincase, receding forehead, stronger occipital ridge = absent in H. ergaster (KNM-ER 3733).

H. ergaster less derived than H. erectus

H. erectus generally more massively built - thicker bone cortices, more pronounced supraorbital and occipital torus, more pronounced postcanine dental reduction

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8
Q

H. ergaster - temporal range, holotype, sites

A

1.9mya to 800kya

Holotype - KNM-ER 992 mandible, Koobi Fora

Sites:
Koobi Fora, Kenya
West Turkana, Kenya
Olduvai, Tanzania
Bouri, Ethiopia
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9
Q

KNM-ER 922

A

Type specimen for Homo Ergaster, found in 1972.

1.5mya

Primitive traits:
Complex premolar crowns
Two-rooted LP3

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10
Q

KNM-WT 15000

A

Nariokotome Boy

West Turkana, Kenya, 1.5mya

Juvenile male (8-12 years old) with tall, thin, long legs - obligate biped

Modern post-cranial skeleton and more primitive skull

880cc at death - adult estimate 909cc
157cm, 50-53kg at death - adult estimate 176-180cm, 80-83kg OR 151-169cm, 46-69kg

Slower and shorter growth spurt than the adolescent growth spurt in modern humans

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11
Q

OH 9

A

Olduvai Gorge, Tanzania

1.1-1.2mya - younger than H. ergaster material

Morphology similar to H. erectus s.s.
Cranial capacity 1067cm3
Pronounced supraorbital torus

Local evolution in Africa or relation to Asian H. erectus?

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12
Q

Variation in H. ergaster

A

OH 9 and KNM-ER 42700 show a high degree of size variation

  • high dimorphism?
  • large temporal separation - 350,000 years
  • two species?

OH 9 - 1067cm3, 1.2mya
KNM-ER 42700 - 691cm3, 1.55mya

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13
Q

UA 31 and BOU-VP 2/66

A

UA 31 - Buia cranium
BOU-VP 2/66 - Daka calvaria

Dated to 1mya, Ethiopia
Relation to the last common ancestor of Neanderthals and H. sapiens?

Like OH 9, more classic H. erectus features

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14
Q

Gona pelvis

A

1.4-0.9mya

Female pelvis
Evolving in response to increasing fetal brain size

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15
Q

The obstetric dilemma

A

Incompatibility between narrow birth canal and large neonatal brain size, resulting from Homo locomotion adaptions and big brains

Consequences

  • Humans strongly underdeveloped at birth - altricial
  • Only 25% of total brain size at birth
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16
Q

Explanations for human altriciality

A
  1. Obstetrical constraints e.g. Rosenberg 1992
  2. Metabolic constraints e.g. Dunsworth et al. 2012
  3. Selective advantages related to neural development e.g. Portmann 1969
17
Q

Altriciality and human brain development

A

Most brain growth and maturation occurs under massive environmental and social influences in our species

Neural circuits responsible for behaviour are shaped by those influences

18
Q

Mojokerto child

A

Java, 1.8mya (disputed)
Only H. erectus infant
1 year old, but perhaps up to 8?
80% of adult brain size (1 year old H. sapiens have 50-60% of adult brain size)

19
Q

Sangiran, Java

A

80 hominin fossils including 10 crania and 14 mandibles/maxillae

Classic H. erectus morphology

1mya or more, but many specimens out of context

20
Q

Pithecanthropus erectus

A

Trinil, Java
Discovered by Eugene Dubois, 1890

H. erectus holotype

21
Q

Javanese vs Chinese H. erectus

A

Javanese ‘Pithecanthropus’:
Sagittal keel
Flat frontal bone
Angled occipital

Chinese ‘Sinanthropus’:
Thick cranial vault
Large supraorbital torus
Surpaorbital sulcus

22
Q

OOA I

A

First hominin migration out of Africa - until this moment, human evolution has been an exclusively African phenomenon

Earliest evidence:
Dmanisi, Georgia - 1.8mya -fossil remains
Shangchen, China - 2.1mya - tools

23
Q

Pleistocene climate oscillations

A

1.8mya-10kya

Colder and more variable climate starting at 1.8mya

Interval marked by repeated glacial cycles, known as the Ice Age

Huge volumes of water in continental ice sheets

Exposed land bridges connecting continents

24
Q

Dmanisi fossils

A

1.8-1.6mya, Dmanisi, Georgia

Closest affinities with H. ergaster
Small bodies and brains
Show more derived features such as an angular occipital bone and sagittal keeling
Arboreal traits in upper arm morphology
Relatively long hindlimbs - modern body proportions
Valgus knee
Foot with arches

550-775cc
145-166cm
40-50kg

25
Q

Dmanisi tools

A

Primitive, Oldowan-like core and flake technology

Sophisticated technology not required for large-scale migrations

D3900 - earliest toothless hominin skull = conspecific care of the elderly?

26
Q

Dmanisi variation

A

Dmanisi individuals expected to belong to the same species - same geographical and chronological context

Variation within Dmanisi encompases from H. habilis to H. erectus

Can H. erectus include all the variability observed in early Homo?

However while neurocranial shape is variable, brain size is consistently ~650cc

Taxonomic affiliations are still under debate

27
Q

Acheulean stone tools

A

1.6mya - 200kya
Mode 2

More sophisticated technology
Symmetrical, biface tools
Retouching, soft hammer percussion

3 classes of core tools

  • Handaxes
  • Cleavers
  • Picks

Many formal flake tools e.g. denticulates, scrapers, burins, borers

28
Q

Movius line

A

Separates H. erectus populations that developed Acheulean tools and those that did not

East Asian populations may have migrated out of Africa before the Acheulean industry developed, or lost the Acheulean industry because they did not find suitable materials

29
Q

Mental template for Acheulean handaxes

A

Tools have very regular proportions & standardised form

Proportions hold for Africa, Near East & Europe

Requires more complex cognitive abilites

Result of sophisticated mental planification

Advanced planning to arrived at product, ability to modify technique to achieve that goal

30
Q

Identification of human-controlled vs. natural fire

A

More intense and longer lasting
Spatially localised and discontinuous

Early record:
Small localised, fully oxidised, magnetically altered sediment patches at Koobi Fora, Kenya (1.65-1.4mya) and Chesowanja
Burned bones from Swartkrans, South Africa 1.5-1.0mya

Earlist conclusive evidence:
Gesher Benot Ya’aqov, Israel
790kya
Charcoal, burned flints, hearths, burned grass seeds and grains (cooking?)

31
Q

Early habitual use of fire

A

300-400kya - only occasional use before this

Cooking - makes food more digestible and can neutralise some toxins

Warmth - important in cold and seasonal environments out of Africa. May have been crucial to allow migrations.

Allows the use of caves as shelters - important in colonisation of European and Asian environments

Predator protection

Hunting - part of complex hunting strategies

Social functions

32
Q

Effect of cooking on human evolution

A 
Externalised pre-processing of food
Less digestion required
Increased efficiency
Smaller, more efficient digestive tract
Linked to expensive tissue hypothesis

If humans did not cook food, we would need to spend the whole day eating to support our big brains - energetically expensive brains

Ways to increase energy intake: increase meat consumption, more efficient hunting strategies, cooking

Palaeoanthropology (9 decks)

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