Chapter 7 Homo erectus. Nariokotome 1984 the bones of an 11 ½ year old boy were found under a tree...
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Transcript of Chapter 7 Homo erectus. Nariokotome 1984 the bones of an 11 ½ year old boy were found under a tree...
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
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: Modern in stature Pronounced areas of muscle
attachment on his long bones
Very thin with narrow hips, and long arms & legs for his height
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
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 emergedBiface
First tools that existed in the minds of their makers as tools
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
Right hand preference Bipedalism allows hands & arms to
gesture Gestures + vocalizations = language
Fire
Homo erectus may have used fire WarmthScaring away predatorsCooking foodSocial opportunitiesCommunal attention
The Homo erectus Adaptive Niche
What we know about Homo erectus: 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
Reasonable inferences… 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
Homo erectus was adept at invading disrupted environments and new locales
Rapid colonization an essential component of the Homo erectus niche
Selective Advantages
Larger territory and more unpredictable food sourceLarge scale spatial thinking selection
Social lifeShape 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
Memory Systems
Procedural memoryChaîne 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 stronglyin isolation the VSSP would operate in
a pre-attentive, implicit fashion