Chapter 7
Homo erectus
Nariokotome

1984 the bones of
an 11 ½ year old
boy were found
under a tree along
a dry stream
channel west of
Lake Turkana
Nariokotome
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Most complete skeleton of an early hominin
ever found.
Died 1.6 million years ago
Know that Nariokotome was an adolescent boy
due to:
 Shape of the pelvis
 Eruption pattern of his teeth
 Unfused condition of growth plates of his
long bones

Surprising characteristics:
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Modern in stature
Pronounced areas of muscle
attachment on his long
bones
Very thin with narrow hips,
and long arms & legs for his
height
Bergmann’s & Allen’s Laws for
Mammalian Body Proportions
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Endocranial volume was 880cc., as an adult
it would have had a capacity of 910 cc.
EQ of 3.3 vs. 3.1 for Homo habilis
Expanded right frontal and parietal lobes
Expanded left occipital lobes
Lower left frontal lobes, assigned to Broca’s
area in modern humans, is larger than the
corresponding region of the right.
* Language abilities???
Altriciality: The young are born
immature and helpless in condition so
as to require care for some time
 Second Altriciality: Newborns have
rapidly developing brains in the 1st
year of life

Homo erectus sensu lato
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Homo erectus: defined on the basis of
Asian fossils
Homo ergaster: African fossils
Geographic distribution distinguishes
Homo erectus from earlier hominins
Homo erectus sensu lato

Homo erectus sensu lato lived in:
 Africa
 Southern Europe
 South Asia
 East Asia
 Southeast Asia

After rapid expansion Homo erectus entered a
period of relative stasis
Mode 2 Technology

1.5 million years ago a new
technology emerged


Biface
First tools that existed in the minds of
their makers as tools
Mode 2 Technology
Other Mode 2 Technology

Mode 2 sites are most often situated in
sand or gravel deposited by streams

They are also situated at higher
elevations in different geographic
settings
Handedness
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Right hand preference
Bipedalism allows hands & arms to
gesture
Gestures + vocalizations = language
Fire

Homo erectus may have
used fire
Warmth
 Scaring away predators
 Cooking food
 Social opportunities
 Communal attention

The Homo erectus Adaptive Niche

Grade shift in cognition
The Homo erectus Adaptive Niche

What we know about Homo erectus:
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Larger than earlier hominins
Reduced sexual dimorphism
Had a larger brain, absolutely, than earlier Homo & a
slightly larger EQ
Had smaller teeth and face
Had a body build adapted for efficient cooling
Lived in a wider variety of habitats
Had dispersed rapidly to many tropical and
subtropical regions of the Old World
Made & used tools of much greater complexity
The Homo erectus Adaptive Niche
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Reasonable inferences…
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Diets contained more high quality foods
Home range of groups were up to 10x larger than
those of other apes
The energy budgets of males & females changed
• “grandmother’s hypothesis” vs. male provisioned
females
Change in life history patterns
Encountered cognitive challenges
The Weed Hypothesis

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Homo erectus was adept at invading
disrupted environments and new locales
Rapid colonization an essential
component of the Homo erectus niche
Homo erectus Cognition
More sophisticated spatial cognition
 Mental templates
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Selective Advantages

Larger territory and more
unpredictable food source

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Large scale spatial thinking selection
Social life

Shape and spatial information
coordination selection
Bifaces & Sexual Selection
Standardized
 None found at butchery sites
 Few signs of heavy use
 Sites found with hundreds, but little
else
 Improvements in appearance, but not
in usefulness

Developments In Skill
Expansion in areas of the motor
cortex
 Arm & shoulder anatomy selection

Memory Systems

Procedural memory


Chaîne opératoire more complex
manufacturing sequence
Working memory

2 main subsystems
Language
Symbols + grammar = language
 Increased length & complexity of
sequential motor action could account
for the expansion of the left inferior
premotor cortex
 Grammar like rules or linguistic
instruction needed for creating
handaxes???

Memory Systems

Less powerful processor?
 Expansion of ST memory system may
have allowed the processing of
sounds, transmission of more
elaborate meanings, and eventually
participation in syntactic processes
Memory Systems

The visuospatial sketchpad & central
executive performance correlate
strongly

in isolation the VSSP would operate in
a pre-attentive, implicit fashion
Memory Systems

Increased LT capacity, especially the
capacity for procedural memory and
expertise