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
Bergmann’s & Allen’s Laws for Mammalian Body Proportions
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???
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 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 : 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
Homo erectus Cognition More sophisticated spatial cognition Mental templates
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
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