Test #3 Flashcards
Trends in the evolution of Homo
Brain gets larger Face gets smaller Premaxilla shrinks More orthognathic Reduction of premolars - Proportionate teeth Increasingly complex behaviour
Homo rudolfensis
East Africa, 2.5-1.8 mya
Cranial capacity: 530-750cc
Similar to H. habilis, but larger/more robust Deep/tall, thick mandible - Direct crushing as opposed to transverse motion Molars are elongated mesio-distally Teeth are proportionate Premaxilla more vertical than australopithecines Transversely broad face - big zygomatics Longer braincase Basicranial flexion Some postorbital constriction Brow ridge (medium in size) Parallel parietals
No known postcrania
Homo habilis
East/South Africa, 2.5-1.5 mya
Cranial capacity ~600cc
Small face, big brain compared to australopithecines Parallel parietals Basicranial flexion High angle of premaxilla - Orthognathy Indication of cerebral asymmetry More proportionate teeth ~4ft tall Relatively long arms - Intermediate between australopithecines and H. sapiens Adducted big toe Arches on feet
Not much temporal change in the species
Homo ergaster
Africa, 1.75-1.5 mya
Cranial capacity 900-1000cc
Continuation of trends in the genus Orthognathic Very shortened premaxilla Begin to see vertical forehead Bulging supraorbital torus Sagittal keel Modern ribcage
Homo erectus
Asia (China)/Africa, 1.8 mya - 50 kya Cranial capacity 900-1000cc Basically modern H. with smaller head First human associated with fire First human out of Africa
Similar to H. ergaster, but more robust **Supraorbital sulcus** Pelvis similar to H. sapiens, more robust in places Femur like H. sapiens Modern limb proportions Thicker cranial bones than H. ergaster Projecting occipital Malar notch
Longer infant development
Lots if intraspecific variation due to large spatial/temporal range
Homo heidelbergensis
Africa/Europe/Asia, 700-200 kya
Cranial capacity: 1100-1300cc
Continuing trends in the genus
Very tall - taller than H. neanderthalensis Huge supraorbital torus - NO sulcus Orthognathic face; mild projection - Visor-shaped midface Vertical forehead
Variation in size: sexual dimorphism or regional variation?
H. heidelbergenisis at Broken Hill
Broken Hill individual shows many cavities
- Would have had to be taken care of; debilitating
The cavities would have moved through the tooth and into the pulp, infecting the root
Homo neanderthalensis
Europe, Asia, Middle East; 250-30 kya
Cranial capacity: 1200-1600cc
Gets more robust as time progresses
Large mastoid process Huge nasal aperture Projecting midface Large brows NO chin Occipital bun Retromolar sulcus Teeth heavily worn - using them to make tools Short relative to H. sapiens (5'5" avg.) Short tibia compared to other Homo Very robust bones A lot of remodeled bone tissue - rough hunting - Evidence of successful amputations
Homo sapiens
Africa, 190kya
More gracile as time progresses Mental eminence (CHIN) Large foreheads Bulging parietals Rounded occipital Canine fossa
Traits associated with increased brain size
Stone tools Cut-mark bones - Tools used to remove flesh, not necessarily hunting (could be scavenging) Higher quality, broader diets Better ability to survive shortages
Traits associated with increased body mass and stature
More efficient bipedalism
Long distance locomotion
- Something that humans do very efficiently
- Form of hunting: walking animal to exhaustion then killing it
Wider ranges
Traits associated with pelvic changes
Brain size increase
Changes in mechanics of bipedalism
Earliest stone tools
Earliest definitive evidence is from Homo
Can’t rule out that australopithecines made stone tools - tools found at sites with both A. garhi/P. robustus and H. habilis
Basicranial flexion
Angle of face to braincase goes from being obtuse angle to more right angle
H. habilis vs H. rudolfensis
Some say they are males & females of the same species, but they are never found together
H. rudolfensis is possibly more modern Same tools More sexual dimorphism in H. rudolfensis H. rudolfensis much larger - Wider variety of foods?
Probably differed in socioecology, diet, ranging behaviour?
H. ergaster vs H. erectus
H. ergaster is essentially the African version
H. ergaster is narrow in the ribcage and hips
- May indicate regional differences due to differing climates
- i.e. Allen’s rule says mammals in hotter climate will be slenderer
- Bergmann’s rule says they will be smaller
Homo and brain reorganization
Larger prefrontal lobes: social complexity
Larger temporal lobes: memory
Larger parietal lobes: integration
Broca’s area: language, tool use?
Cerebral asymmetry: lateral specialization
Life history in H. ergaster
Turkana boy died age 10-12
- Consistent with human pattern, where M2 erupts at 12
Secondary altricality
Human babies are born somewhat prematurely
- Brains grow at fetal rates for a year after birth
- External stimuli directly affect neuronal interconnections
Infant brain size is 30% of mothers in humans and 50% in chimpanzees
Midsagittal keel
Ridge on head that is not associated with muscle attachments (i.e. not a crest)
- “House-shaped” head
H. erectus at Dmanisi
1.85 mya
Specimen who had lost all his teeth - would have had to be taken care of
Fontanelles
Soft parts of a baby’s head, allows for continued brain growth after birth
H. heidelbergensis at Bodo
Cut marks on the bone along brow ridges & orbits
Hypotheses include cannibalism & scalping:
- No strong evidence for cannibalism (no crushed bines, cut marks near muscle)
- Likely of symbolic significance
Gab between H. ergaster and H. sapiens in Africa
Specimens that are more modern than H. ergaster or H. heidelbergensis
- Argument over gracile H. heidelbergensis or new species
Smaller brow ridges
Face not visor-like
Globular braincase
Gracile
Probable spear points found near sites
