BioAnthro Final Flashcards
Locomotion
Bicondylar Angle
In humans, the femur angles inward, keeping the legs more directly under the body.
Locomotion
Human foot
- No deposable first toe
- Calcaneus much bigger tan in chimps
- Weight distributed on 2 feet constantly
Calcaneus: The large bone forming the heel of the foot
Bipedalism
How old and present in which oldest human ancestor?
- Currently is 6 - 7 mya
- Defining characteristic for hominins
- Earliest bipeds not “fully” bipedal
- Present in the australpithecous skeletons from Africa, the oldest species that we are for certain had bipedalism.
Bipedalism
Why are we bipedal?
This is a trick question, while we have theories on why, we actually don’t know
Locales
South Africa
- Different from the rest of Africa (in terms of preserving fossils)
- Has different variations of plants and animals
-Hominins from S. Africa don’t necessarily fit into human evolution - Dominated by limestone (caves, nooks, and crannies, crevasses)
- Brits colonize S. Africa and blow shit up ⟾ fossils come out
People
Raymond Dart
- 1925: the 1st discovery of human ancestors in Africa
- Solidified the idea that bipedalism didn’t come from big brains
Human Ancestor
Taung Child
- Taung (gracile Australopithecus)
- Skull, mandible, endocast, teeth
- Biped with a really small brain and large teeth for its age
The Foramen magnum position indicates bipedalism
Discovered by Raymond Dart
Human Ancestor
Robust Australopithecus
- Lived during the Pliestocene: 2.5 - 1 mya
- East Africa on West side of Lake Turkana
- “Chunkier”
- Thicker mandibles
- Large chewing muscles
- Very large teeth: Post canine megadontia with small canines and incisors
- Crests - Sagittal, Nuchal
- Post-orbital constriction
- Differences are only in craniums, not in bodies
Human Ancestor
Australopithecus aethiopicus
- West Turkana
- 2.5 Ma
- 410 cc
- lived in closed habitats in Eastern Africa
- Incredibly sloped face (dished)
- Foramen Magnum points inferiorly
- Large zygomatic bones and arches
- Largest posterior sagittal crest in human evolution
- Ate tough foods; chewed a lot
- Stripper hypothesis
- Displays cases of evolution to eat fall-back food
- Sexual dimorphism?
“The Black Skull” - KNM-WT 17000
Human Ancestor
Australopithecus boisei
- Found in Lake Turkana, Kenya,
- Lived during the Pliestocene between 2.5 - 1 mya
- Average cc: 450-550 cc
- Lived in open grasslands and woodlands
- Sagittal crest is smaller and more superior
- Suggests they are not stripping
- Grinding their food
- Tubers; USOs in the savanna. They contain a lot of sugar. They store water. Extracting them from the ground with digging sticks.
- *Molarized premolars (Post-Canine megadontia) *
- Reduced anterior teeth distinguishes them from Au. afarensis
- Sexual Dimorphism
- Skull shape is similar but size is different
- Diamond-shaped face; smaller sagittal crest
- Descendants are a topic of debate
Human Ancestor
Australopithecus robustus
- Lived during the Pliestocene between 2.5 and 1 mya
- Swartkrans Cave, Africa
- Avg cc: 530 cc
- Molarized premolars, Very small incisors, Body of mandible is very thick
- Dietary plasticity - Possibly eating termites (which contain fat)
- Open grasslands and woodlands in Sourthern Africa
- Unsure of descendants but is sometimes considered to be descended from other Robust Aus.
Human Ancestor
Homo habilis
- Lived between 1.5 - 2.3 million years ago
- Tanzania and Kenya
- They were bipedal
- 612 cc
- They are believed to have been the first hominid species to use stone tools
- Compared to A. boisei: differences in premolar size and morphology clearly showed a transition to Homo
- ~ 4ft tall; weighted about 80-90 lbs
- show precision and power grip
- More vertical forehead
Tools
Benefits of Stone Tools
Wider resource exploitation
- increased meat consumption
- more processing of vegetable material
Hominins
Hominin-Evolution
Human evolution post-chimps
- Displays bipedalism leads smaller canines, larger brains, and tool use
Bipedalism
Knuckle-Walking vs Bipedalism
Significant changes in the hip, knee, and ankle joints
* Bipedalism = longer legs, shorter arms, pelvis orientation, skull orientation on vertebrae w/ foramen magnum pointly inferiorly
* Knuckle-Walking = ape curve spine, posterior-facing foramen magnum, torque produced by body weight, simple stabalization
Bipedalism
Frankfurt Horizontal head aligment
Human: foramen magnum points down (inferior)
Apes: foramen magnum points posteriorly
Bipedalism
Pelvic orientation
- Apes: Torque produced by body weight, gluteal muscles are extensors to help them project forward quadrapedally or simple stablization
- Hominins: Torque from abductor muscles for balancing, muscles working to keep us upright are gluteal muscles - bring leg and pelvis closer causing a flaring iliac blade of pelvis in hominins
Bipedalism
Types of Bipedalism
- Occasional Bipedalism
- Habitual Bipedalism
- Obligate Bipedalism
- Random Bipedalism
Types fo Bipedalism
Occasional Bipedalism
Incorporating it into routine but it is not the only way of movement
Homo (2.3 mya - today)
Autapomorphy: uniquely derived trait
Types of Bipedalism
Habitual Bipedalism
- Using it very frequently, on ground
- However, still can hang out in trees
Australopithicus (4.4 mya- 2 mya)