homonin evolution Flashcards
lect 5,6,7,8
Sahelanthropus tchadensis
- first entry on chart
- transitional species
- 6-7 mya
- found in Chad
- Foramen magnum positioned to the rear of the skull
- Horizontally oriented basicranium
- Thick supra-orbital torus
- Long narrow brain case
- found by??
human and apelike characteristics of Sahelanthropus tchadensis:
some human features: ??? apelike features: -small brain, -projecting face, -sloped forehead and -large neck muscles.
Ororrin tugenensis
- second entry on chart
- fount in Tugen Hills of Kenya
- 6 Ma
- Small teeth but thick enamel
- Femur suggests bipedality
- found by ??
Ardipithecus Kadabba
- third entry on chart
- found in Ethiopia
- 5.6 million years ago
- Known only from teeth and fragments of skeletal bones
- Originally described as subspecies of Ardipithecus ramidus, now considered a possible ancestor of the latter (based on discovery of additional teeth).
- found by ??
Ardipithecus ramidus
-fourth entry in chart
-found in Ethiopia
-had a small cranium
-Gracile limbs
-Bowl shaped pelvis
-4.4 Ma
-Basal foramen magnum
-Toe bone similar to later
bipedal hominins
- found by??
Australopithecus anamensis
- fifth entry on chart
- Found at Alia Bay and Kanapoi, Kenya
- Mosaic of ape and human features
- Parallel tooth rows
- Hind limbs suggest bipedality
- 4.2 to 3.9 Ma
- found by???
Australopithecus afarensis
- Gracile australopithecine
- 4.0 to 2.9 Ma
- Found in Hadar, Ethiopia, -Kenya and Tanzania
- The most well known hominin
- Clearly a biped
- Ape-like limb proportions
- Large sexual dimorphism
- Still some arboreal adaptations
- found by??
Kenyanthropus platyops
-3.2 -3.5 Ma
-Western side of Lake Turkana basin in Kenya
-Tall cheek region and flat face
-Small teeth
-Mixture of ape and human traits
-Badly damaged skull
-Bipedal??
- found by ??
controversial fossil - very fragmented
Australopithecus africanus
- Gracile australopithecine
- 3.2 – 2.1 Ma
- Southern Ape from Africa
- Australopithecus africanus
- Raymond Dart – first described species
Paranthropus aethiopicus
- 2.5 Ma
- Earliest known robust australopithecine
- Eastern Africa (Turkana basin of northern Kenya, southern Ethiopia)
- Black skull
- Very few remains of this species have been found – still a mystery
- Strongly protruding face, large megadont teeth, and a -powerful jaw, and a well-developed sagittal crest
Paranthropus robustus
found in South Africa
2-1.5 mya
Paranthropus boisei
found in east Africa
lived 2.5-1 mya
what does the term “Gracile australopithecines’ mean?
slighter build prognathic face smaller teeth steeper forehead smaller temporal fossa longer snout no crest face sits below neurocranium steeper forehead incisor prognathism less robust mandible example: Australopithecus africanus
what does the term robust australopithecines mean?
more robust sagittal crest massive teeth larger temporal fossa shorter snout face is hafted, high on neurocranium flatter forehead flatter face more robust madible
Australopithecus garhi
- Found in middle Awash Ethiopia
- 2.5mya
- apelike face
- large teeth
- small brain
- associated with tool use - Olduwan type
Australopithecus sediba
- 1.95-1.78 mya
- found in COHK Joburg
- mosaic of homo and aus traits
- Cranial capacity similar to that of Australopithecus, but jaw and teeth are gracile like those of early Homo
- found by Lee Burger
Australopithecus sediba similarities with Homo
front of brain reorganized projecting nose smaller teeth and chewing muscles hips are less flared and similar to humans longer legs precision grip
Australopithecus sediba similarities with Australopiths
smaller brain size long and high cheek bones primitive molar cusps small body size longer upper limbs primitive heel bone
what were some of the earliest homo individuals found?
homo rudolfensis
homo habilis
found on the eastern shores of Lake Turkana
dated - 2.0-1.9 mya
homo rudolfensis
more australopith face
larger brain
2.0-1.9 mya
Lake Turkana
homo habilis
more australopith/smaller brain more human face
2.0-1.9 mya
Lake Turkana
homo habilis shared traits with Aus afarensis
low body mass
teeth adapted to tough foods
Arboreal and terrestrial adaptation
development stages african apes
homo habilis shared traits with erectus
stone tools
larger brain
homo erectus
first hominin species to leave africa major anatonical changes brain size 1000cc bipedalism is more modern reduction in sexual dimorphism association with well made stone tools - Acheulean hand axe found by ?? found where?? lived 1.5 mya
homo heidelbergensis
-800k-200kya
-Africa and Europe, possibly Asia
-mixture of sapiens and eretus features
-massive brow ridge
-forwardly projecting face
-robust build
-thick walled skull
-larger brain capacity
-Rear of cranium is more rounded
-reduction in post canine tooth size
found in Heidelberg germany
found by ??
found in ??
what is the Sima de los Huesos
13m shaft where many remains found
32 individuals dropped down ceremonially or disposing of dead
one reddish handaxe
Neanderthals
Neander valley - germany lived - 150k - 28kya -retromolar gap -occipital bun -projecting mid face -no chin -heavily built, short and stocky -bones are thicker
adaptations for colder climates and the rules governing that
Bergman and Allen’s rule - heat loss reduction
- organisms that are shorter and ticker and more robust are built for shorter climates so that less heat is lost
- animals in colder climates have shorter and stockier limbs
homo sapiens
Reduced robusticity
everything becomes smaller
back teeth continue to reduce so do front teeth
-cranial buttresses much less in evidence
-loss of brow ridge
-development of chin
-sexual dimorphism reduces to modern levels
-vertical forehead
-canine fossa*
-pyramidal mastoid process*
what are the three theories of modern human origins?
complete replacement model
regional continuity model
partial replacement model
explain the complete replacement model as a theory of modern human evolution
- developed by british paleontologists Christopher Stinger and Archeol. peter Andrews
- proposes that anatomically modern populations - Sapiens replaced Heidelbergensis in Africa
- migrated from Africa and completely replaced descendent populations of erectus in europe and Asia- they out competed them
problem with the complete replacement model?
-doesnt account for the transition from heidelbergensis to sapiens anywhere else other than africa
explain the partial replacement model as a theory of modern human evolution
- proposed by Bunter Brauer of the uni of Hamburg
- Erectus moved out of africa and settled in the of the globed - eventually giving rise to heidelbergensis around 100kya
- Thes H. sapiens moving into Eurasia, and hybridized with resident groups (non H. sapiens descendants of H. erectus) , eventually replacing them.
- The disappearance of these archaic humans outside of Africa was due to hybridization (interbreeding and not complete replacement) and replacement.
another name for the partial replacement model
the assimilation model
explain the regional continuity model as a theory of modern human evolution
- Associated with paleoanthropologist Milford Wolpoff of the University of Michigan.
- H. erectus moved from Africa to Eurasia around 2 mya and gave rise to H. heidelbergensis in the various regions.
- Human populations in Europe, Asia, and Africa continued evolutionary development from H. heidelbergensis to anatomically modern humans.
- No en mass migration of H. sapiens from Africa into the rest of the world.
- However, limited gene flow between regions.
what is the most accepted theory?
The out of africa hypothesis - replacement
what are some predictions that come along with a replacement hypothesis?
- The oldest anatomically modern specimens will be in Africa
- Transitional forms will be in Africa
- Co-existence of ancient modern sapiens and archaic forms outside africa
- archeological evidence for modernity should appear in africa first
where was some evidence of modernity found in africa and when was this evidence from?
Blombos cave
100k-70kya
