Hominin Origins Flashcards
In humans, males are on average ____% larger than females.
Males are on average 15% larger than females.
What social structure do people naturally have?
Polygynous
Describe Piltdown man.
It was a hoax, in 1950s exposed
“Eoanthropus dawsonii
Found in Sussex gravel pit
Ape-like jaw
Lots of people thought the big brain came first and they would still have a primitive jaw so it fit the preconceptions of the time and that’s why people believed it.
What was the habitat like during the time of the early hominins?
1) Pliocene habitats were dry
2) East Africa Rift Vally forms rain shadow (with rain shadow you lose a lot of rainforest and get expansion of savannah)
What is a supraorbital torus?
Brow ridge
Describe Sahelanthropus tchadensis
1) Chad
2) 6-7mya
3) about 62kg
4) Robust supraorbital torus
5) Short subnasal region
3) Vertical upper face
4) Similar sized brain to Pan
6) forward position of foramen magnum (bipedal)
7) Smaller canines with apical wear indication occlusion. (Small canines like us)
Describe Ardipithecus Kadabba
1) Ethiopia hominin
2) 2.8-5.2mya
3) Finger bones were curved so was at least partially arboreal but was also bipedal on the ground
Could be bipedally arboreal but the toe bones are usually curved if bipedal in trees
Describe teeth of Ardipithecus kadabba.
1) Taller canine than in later taxa –> instead of occlusion it will go past and hone against pre-molar
2) Diastema (it has one for the lower canine to go)
Describe postcrania of Adripithecus
1) Long arms (high intermembral index) so it was probably spending lots of time in trees
2) No knuckle walking features
3) Divergent hallux
4) Short, wide ilium (only seen in people amongst extant apes)
This indicates bipedal pelvis might have evolved before big toes was in line in others
Describe Australopithecus anamensis.
1) 3.9-4.1 mya, Kenya
2) 47-55kg
3) Open habitats)
List the primitive dental features of Australopithecus anamensis.
1) Large, stout canines
2) Thick mandible (people have narrow mandibles)
3) Parallel tooth rows (whereas in people it’s wider at the back than at the front)
List the derived dental features of Australopithecus anamensis
1) Broader molars
2) Thicker enamel (unlike gorillas and chimps but like us)
Explain how the postcrania of Au. anamensis is similar to the postcrania of humans
The condyles are large where the femur joins the tibia, which you see in people.
If you’re a biped the surface of the joint has to be wider to take the extra weight!
Describe Praeanthropus afarensis.
A.K.A Australopithecus afarensis
1) 3.6-2.8mya, Ethiopia and Tanzania
2) Lots of specimens
3) Prognathic (due to front dentition large compared to people)
4) Large incisors (Unlike people)
5) EQ = 2.5 (Pan is 2.0)
6) Long forelimbs
7) Short stature
8) Pronounced sexual dimorphism (polygynous)
9) Some have distema and some don’t (so it is in the process of changing)
10) Curved phalanges (still spending time in trees)
11) Scapula tilted slightly posteriorly due to arms being held above head a lot
12) Short and wide ilium (bipedal)
13) knee is valgus (bipedal)
What is Lucy’s fossil code?
AL 288-1
Praeanthropus afarensis
Indicates bipedalism before brain expansion
Describe the bipedal features of Lucy.
1) Valgus knee
2) Lumbar curve (puts pelvis directly below centre of gravity
3) Short, curved pelvis
Describe the arboreal features of Lucy
1) Cone shaped torso (unlike humans in which it is more barrel shaped)
2) Broad, muscled shoulders
3) Curved phalanges
How did Lucy die?
Fracture pattern suggests fall
What do the Laetoli footprints reveal about Lucy’s kind?
1) Bipedal
2) Footprints in volcanis ash 3.66mya
Two hominins walked together and one was larger than the other. No knuckle marks so it wasn’t using it’s forelimbs to walk. Also showed hallux was in line with other toes.
Footprints also show they had an arched foot (hominin trait)
Describe Australopithecus garhi.
1) 2.5 mya, Ethiopia
2) Very large molars, no diastema
3) Prognathic
4) Long, ape-like arms
5) Femur lengthened so intermembral index is similar to humans
6) Tools and evidence of large animal butchery
Describe Taung child.
1) Australopithecus africanus
2) Found in Africa,
3) 2.3mya
4) Foramen magnum forwardly places
5) No browridge (like us)
6) High forehead
7) No projecting canine
8) Parts of brain expanded
Why was there scepticism surrounding the Taung child?
1) Jaw of human and brain of ape is unlike piltdown
2) Would mean Africa was the home of hominins
3) It’s a child (adult could look different)
Describe the cranium of Australopithecus africanus
1) Braincase more domed than Pr. afarensis
2) Brain 430-480cm3
3) EQ= 2.7
4) Face deeper and less projecting
What does the reduction in incisors and canines and large molars in Au. africanus reflect?
Reflects shift away from slicing towards crushing and grinding
They also had thicker enamel
What is Mrs Ples?
STS 5
Adult Au. africanus
1) 2.5mya
2) Showed Taung child was not an ‘ape’
3) Oldest hominin individual in the fossil record (short incisor from heavy wear)
What is the EQ of Pr. afarensis?
2.5 (larger than a chimp with 2.0)
