7 - early human evolution Flashcards
australopith species and dates
austolopithecus anamnesis 4.2 - 3.9 mya
afarensis 3.9-2.9 mya
deyiremeda 3.5-3.0 mya
bahrelghazeli 3.5-2.0 mya
africanus 3.5-2.0 mya
garhi 2.5 mya
sediba 1.9 mya
When was the first australopith discovered
- 1924 in South Africa - found by quarry workers and studied by Raymond Dart
- informally ‘tuang child’
- Australopithecus africanus -
- forwardly placed foramen magnum, no projecting diastema
Second found australopith
1947 - Sterkfontein, south africa
STS 5 - ‘Mrs Ples’ 2.5 mya
clearly bipedal
Australopithecus anamensis
- 1st found 1995 - Maeve Leakey - Lake Turkana, East Africa
- teeth more primitive than later hominids (larger canines, dental arcade u shape)
- tibia thickened at both ends as a result of weight bearing in bipeds lower limb
- arm bones still adapted for life in trees
First Australopithecus afarensis found
1974 - Donald Johanson - Hadar (ethiopia)
“Lucy” - AL288-1
40% complete skeleton
just over 1m tall
brain size like an adult chimp ( c 400 cc)
bipedal before brain expansion
anatomy mosaic of human and ape like features
crania and postcrania of Australopithecus afarensis
CRANIA
- cranial capacity small c 415cc
face prognathic
dental arcade u shaped with large front teeth (like ape)
POSTCRANIA
- thorax funnel shaped, possibly due to large gut from vegetal diet)
- arms longer relative to leg length
- strongly muscled shoulders
- curved phalanges on hand and feet
A. afarensis - Biped
POSTCRANIAL BIPEDAL ADAPTATIONS
- Pelvis - short iliac blades curved around side
- femur angled towards knee
- tibia modified to bear more weight
EXAMPLE
- Laetoli footprints, Tanzania 3.5 mya
- trackway of a.afarensis individuals
- show longitudinal arch
- big tow in line with others
Kenyanthropus Platyops
3.5 - 3.3 mya
- robust face: deep and flat face and strong cheek bones
- small cheek teeth
- but constructed of many tiny fragments - maybe just Australopithecus afarensis
Australopithecus deyiremeda location
Ethiopia, near Hadar site (Australopithecus afarensis) - more than one homini species same time and place
australopithecus deyiremeda maxilla and mandible
teeth smaller than Australopithecus afarensis, mandible more robust, different diets? niche partitioning?
Spoor, F (2015) Nature
Australopithecus africanus location
South Africa e.g. sterkfontein, makapansgat, swartkrans
A. africanus cranium
- larger brain case ( 450-550cc) than afarensis, and more rounded vault. less prognathic
dentition:
- incisors and canines smaller than afarensis but molars larger.
-shidt from slicing to crushing/grinding
A. africanus postcrania
very similar to a.afarensis, still adaptation for arboreal behaviour.
e.g. STS14 - 2.5 mya - found 1947 - Robert Broom
-outward flare of iliac blades (like afarensis)
-lumber curve in back
- 6 lumbar vertebrae (5 in modern humans)
australopithecus garhi
- 1999, Bouri, Ethiopia
one partial skull with large teeth - small brain (c450cc) + prognathic face
- post cranial material nearby - same species? (long femur like humans and long arms like apes) (found with tools and evidence of large mammal butchery)
- ancestral to homo?
australopithecus sediba
2008, Malapa in South Africa
(2 partial skeletons - one juvenile, one adult)
- habitually bipedal
- descended from africanus
- ancestral to homo?
autralopith characteristics and homo characteristics on autralopithecus sediba
Australopithecus characteristics
- small cranial capacity c400cc
- small body size
- long arms
Homo characteristics
- features of pelvis
- teeth similar size to homo
small post canine dentition
Robust australopithecines / Paranthropine species
Genus : Asutralopithecus
Species:
aethiopicus 2.7 - 2.5 mya
boisei 2.3 - 1.2 mya
robustus 2.0 - 1.5 mya
gracile vs robust
changes in skull morphology not body build
Paranthropus: crania and teeth
share chewing specialisations
- massive jaws
- huge crushing/grinding teeth
- sagittal crests
- adaptations to chewing tooth food items e.g nuts and seeds
- produce large bite forces - chewing muscles maximised in size and placement
Paranthropus aethiopicus ‘the black skull’
East Africa - Lake Turkana, Kenya - 1985
- Huge molars and large anterior teeth
- very prognathic dished face, flared zygomatics
- small brain c400cc
- prominent sagittal crest
Earlier than P.boisei and P.robustus but only shares distinctive features with P. Boisei (ancestral?)
Paranthropus boisei
East Africa - Ethiopia, Kenya and Tanzania
- cheek teeth massive, front teeth small and crowded
- brain 500cc
- face plate and deep - facial buttressing
- flaring cheekbones
P.boisei example
OH5 - “Zinj”
- Mary and Louis Leakey
- 1.8 mya
- massive skull, broad concave face
- molars x4 modern
Paranthropus robustus
South African - Komdraai and Swartkrans
- brain size c500-550cc
- heavily built face and jaws
- small anterior teeth
how does P.robustus differ from P.boisei
- massive cheek teeth but not as big as P.boisei
- shape of nasals
- bow ridge
- presence of bony pillars next to the nose
What Homo species existed pre 2.0 mya
homo habilis c 2.3-1.6 mya
Early homo
first signs of ‘human-like’ behaviour e.g. making and using stone tools
BUT some not that different from australopiths (homo Habilis small brains, primitive post cranial skeleton)
some australopiths also probably used tools
homo habilis
East Africa and South Africa
- larger brain than australopiths c500-700cc
- smaller teeth and more parabolic dental arcade
- more rounded cranium
- smaller less portruding face
homo habilis face
- short and lightly built
- still quite prognathic
- face tucked under braincase
- smaller teeth
homo habilis postcrania
- forelimbs long robust and strongly muscled
- hindlimb short and relatively lightly built
- more primitive proportions than Lucy
Tool use
-oldowan tools
- olduvai gorge
Homo rudolfensis years
c 2.5 -1.9 mya
Homo rudolfen
bigger brain than h.habilis 750-800cc
face large and flat - strongly constructed - cheekbones wide and deep
mandibles strongly built, front teeth fairly large, larger molars than homo erectus
