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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.

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Presentation on theme: "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."— Presentation transcript:

1 Chapter 7 Homo erectus

2 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

3 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

4 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

5 Bergmann’s & Allen’s Laws for Mammalian Body Proportions



8 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???


10 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 1 st year of life


12 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

13 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

14 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

15 Mode 2 Technology

16 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

17 Handedness Right hand preference Bipedalism allows hands & arms to gesture Gestures + vocalizations = language

18 Fire Homo erectus may have used fire Warmth Scaring away predators Cooking food Social opportunities Communal attention

19 The Homo erectus Adaptive Niche Grade shift in cognition

20 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

21 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

22 The Weed Hypothesis Homo erectus was adept at invading disrupted environments and new locales Rapid colonization an essential component of the Homo erectus niche

23 Homo erectus Cognition More sophisticated spatial cognition Mental templates


25 Selective Advantages Larger territory and more unpredictable food source Large scale spatial thinking selection Social life Shape and spatial information coordination selection

26 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

27 Developments In Skill Expansion in areas of the motor cortex Arm & shoulder anatomy selection

28 Memory Systems Procedural memory Chaîne opératoire more complex manufacturing sequence Working memory 2 main subsystems


30 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???

31 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

32 Memory Systems The visuospatial sketchpad & central executive performance correlate strongly in isolation the VSSP would operate in a pre-attentive, implicit fashion

33 Memory Systems Increased LT capacity, especially the capacity for procedural memory and expertise

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