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SDSU / Engineering / ANTHRO 101 / What does hominin mean?

What does hominin mean?

What does hominin mean?

Description

School: San Diego State University
Department: Engineering
Course: ANTHRO101
Professor: Jeffrey peterson
Term: Fall 2018
Tags: Introduction to Cultural Anthropology, Anthropology, and Hominins
Cost: 50
Name: Study Guide #3
Description: These notes are on early hominins, during the Plio-Pleistocene epochs
Uploaded: 11/09/2018
10 Pages 23 Views 6 Unlocks
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Terms


What hominin means?



● Hominin:

○ The division (called a tribe) in the superfamily Hominoidea that includes humans and our recent ancestors

○ Bipedal apes with specific characteristics like small canines, large brains, slow life histories, and cultures and languages

○ Evolved in the Pliocene epoch (its getting cold!)

● Bipedal Anatomy

○ Set of anatomical adaptations that make it possible for an animal to use 2 legs for locomotion

○ Includes skull, spine, pelvis, and legs

● Spine

○ Spine is S-shaped while quadrapeds have C-shaped spine

● Foramen Magnum

○ Opening at the bottom of the skull where spinal cord connects to brain


What is bipedal anatomy?



○ Its at the bottom of skull for humans so spine can be upright underneath us

● Illium

○ Top of the pelvis

○ Its short, wider and sturdy to hold up a human while they walk

● Abductor muscles

○ Muscles in the hip that contract to move your legs away from body

○ Torque is created when one leg is lifted, pulling that side of the body towards the imbalance

● Bicondylar Angle

○ Angle at which the femoral shaft is perpendicular to the infracondylar plane, basically your femur is angled inwards towards your knee

○ Not born with this but it develops as you grow and keep walking


What abductor's muscles mean?



○ Femur: femoral neck is long and unevenly thick We also discuss several other topics like What does it mean when a firm has comparative advantage?

○ Feet: arched feet to cushion the blow of walking and stores energy

● Nonabductable Hallux

○ Non-grasping big toe

● Facial prognathism

○ When the face juts out, like a snout

○ The jaw projects beyond the upper part of the face

● Mastoid process

○ A conical prominence of temporal bone behind the ear

● Parabolic dental arcade

○ Dental shape is like a parabola, used to be more U-shaped then it widened out ● Bicuspid

○ First premolar

● Shearing Complex

○ Canines and premolars created a self sharpening complex

● Sectorial Premolar

○ First lower premolar that exhibits lateral compression due to its role as a shearing surface for the upper canine tooth

● Sagittal Crest

○ Larger temporalis muscles, helps chew tougher foods

● Megadontia

○ Large teeth

● Zygomatic Arches

○ cheekbones

● Mode1 Oldowan tools

○ Flakes, hammers, cores

● Mode 2 Acheulean stone tools We also discuss several other topics like What are the social consequences of the growth of imbalance?

○ Found 1.4-1.6 mya

○ Biface, specifically designed for carcass processing

○ Remained unchanged for 1 million years

○ Right handed

● Post-Orbital Constriction

○ narrowing area behind the eyes

● Brow ridge

○ Bony buttressing of bone over the eyes

● Occipital torus

○ Bony part on the back of the skull

● Turkana boy

○ Nearly complete skeleton of a 12 yr.old who was discovered by Lake turkana ○ Was part of Homo ergaster We also discuss several other topics like What is linear electron flow?

○ Learned about H. ergaster from him, about long distance running, narrow hips, maybe used some language?

● Sagittal keel

○ Thickening of bone on part, all of midline of frontal or parietal bones

● Taphonomy

○ Study of what happens to bones after death; study of fossilization

● Island Dwarfism

○ Happens when an entire species is secluded on a land mass and become smaller than other species on other land masses

○ Related to resources, finding their niche, almost like adaptively radiating but smaller

What are the four main hypotheses for the evolution of bipedalism?

1. Feeding adaptation:

a. Dwindling of trees and increase in savannah forced them to walk upright to travel

2. Energetics: If you want to learn more check out How does the federal reserve affect monetary policy?
If you want to learn more check out What do micro finance institutions do? what role can they play in reducing poverty?

a. Bipedalism saves energy and is more efficient than knuckle walking

3. Thermoregulation:

a. Dwindling of trees = increase in savannah

i. Less surface area = less solar radiation

ii. More wind

4. Carrying and provisioning 

a. Needed hands to carry food

Timeline:

Early Pliocene (about 4 - 6 million years ago):

- Lots of climate fluctuation

- Most fossils were found in the East Africa (mountain range) - Also in Chad (which is in the middle of Africa, very far away) ★ Sahelanthropus tchadensis 

○ Chad, Africa 6-7 mya

○ Hominin?

■ Yes

● Foramen magnum suggests bipedality

● Small canines; no shearing complex Don't forget about the age old question of What is pauli's exclusion law?

● Thick molar enamel

● Flat face/ less prognathism

■ NO bc:

● chimp size brain, brow ridge

○ Found right around when chimps and apes diverged ★ Orrorin tugensis 

○ 6 mya, Kenya

○ Mix of woodland and savanna

○ limb bones, mandible

○ Hominin?

■ Yes

● Thick molar enamel

● Femur suggests some bipedality

■ No

● canine chimp teeth

● Robust arm bones and long curved fingers

★ Ardipithecus ramidus 

○ 5.8-4.4 mya

○ Found in Ethiopia

○ Unique combination of terrestrial and arboreal adaptations ○ Just under 4 feet tall (slightly taller than chimpanzees) ○ Around 110 pounds (slightly larger than a chimp)

○ YES its a hominin:

■ Small, dull canines with no shearing complex

■ Thicker enamel than a chimp

■ Together with small incisors suggests diet of less fruits, more seeds and nuts

■ Reduced prognathism

■ Bipedal anatomy

● Foramen magnum more centrally located underneath skull

● Short and stout ilium

● rigid/ stiff foot

○ NO

■ Small brain

■ Arboreally adapted

● Ischium has large attachment for hamstrings

● Grasping toe

● Flexible wrist and short metacarpals suggest walking on top of

branches

★ Australopithecus anamensis 

○ Kenya and Ethiopia 3.9-4.2 mya

○ Grassy woodland environment

○ 78 fossils found, no skulls only dental, arm, finger, leg bone

○ Bipedal anatomy

■ tibia (expanded knee area, human like ankle)

■ But has long arms and curved fingers which means it could be arboreally adapted

■ Ancestral dental arcade (U shaped)

■ Hominin like teeth

● Smaller canines

● No shearing complex

● Thicker enamel than Ardi

- 2010: fossils found at a site in Ethiopia, have both features of Anamensis and Afarensis, bridges the gap in features)

Mid Pliocene (about 3 - 4 million years ago)

★ Australopithecus afarensis 

○ Ethiopia and tanzania, 3-3.6 mya (includes Lucy)

○ Woody grassland

○ Sexual dimorphism

○ Brain size is slightly larger than chimp brain

○ Subnasal prognathism

○ Attachments on skull for powerful chewing muscles

○ Broad, pneumatized skull base

○ Intermediate teeth

■ More rounded dental arcade

■ Large molar teeth

■ Smaller diastema than chimps

■ Larger and more dimorphic canines than humans

■ Semi bicuspid third premolar

○ Locomotion

■ Bipedal:

● No grasping big toe

● Partially arched foot

● Functional abductor

● Bicondylar angle knee/ femur

● Proportionally shorter legs than humans

● Footprints!!

■ Some tree climbing:

● Longer and more curved fingers than humans

● Scapula shaped similar to gorilla

● Predator avoidance?

○ Dikika Child, “Selam”

■ Dikika, Ethiopia

■ 3.3 mya

■ 3 year old female, full skeleton

■ Slower brain maturation: Reliance on learning

● A. afarensis was at 75% of brain growth

● Chimp would be at 90% at 3yrs

■ Found a hyoid bone (allows for us to speak)

○ Started forming chin

★ Australopithecus bahrelghazalia 

○ 3.3 mya in Chad (central africa)

○ Only found a mandible

○ Don’t know much about it (is it a new species?)

★ Australopithecus africanus 

○ 2.2-3 mya

○ Woody grassland

○ Body size dimorphism

○ Cranially its about the same size as afarensis

■ Bigger molars, smaller canines

■ Rapid tooth development

○ Bipedal but some tree climbing

○ Southern Ape of Africa

○ Taung Child

■ Foramen magnum = bipedal

■ Small deciduous canines

■ Challenged large brain first idea

○ Sterkfontein Cave

■ Mrs. Ples

■ Hundreds of fossils

○ “Cradle of Mankind”

■ Hundreds of fossils

★ Kenyanthropus platyops 

○ 3.2-3.5 mya

○ Cranial:

■ Small brain

■ Flat face

■ Small molars

○ Postcranial: nothing

○ Alternative to Australopithecus?

Plio-Pleistocene boundary (about 1.8 to 3 million years ago)

★ Australopithecus garhi 

○ 2.5 mya in East Africa

○ Found in middle Awash study area in ethiopia

○ Descendant of afarensis?? Traits suggest this lineage

○ Cranial

■ Similar sized brain as afarensis

■ Sagittal crest (for attachment of temporalis muscle)

■ Large premolars and molars

○ Surprise?

■ Long legs found near skull

■ Stone tools- found bone with stone tool cut marks, but never found the actual tools

★ Australopithecus sediba 

○ Found in southern africa (found an adult female and juvenile male) 1.7 mya ○ Date 1.98 mya, latest occurring australopithecene

○ Cranial

■ Small brain

■ Teeth like A. africanus, suggesting phylogenetic connection

■ Teeth were smaller- reduced musculature for chewing? Linked to our own genus Homo?

○ Eating?

■ Phytolithic analysis

■ Phytoliths: preserved plant material from tartar on surface of teeth

■ Isotopic signature of phytoliths

● Diet of fruit, leaves, bark

○ Humanlike hands, humanlike pelivs

○ Arboreal adaptations: long arms, thorax was more ape like, foot was even more primitive

■ Primitive foot: narrow and angled heel bone (like chimp), humans are more robust and flat heel bone→ suggests unique form of bipedal walking (hyperpronation)

★ Paranthropus aethiopicus 

○ Kenya

○ 2.5 mya

★ Paranthropus robustus 

○ South africa

○ 1-.18 mya

○ Cranial and dental adaptations for heavy chewing

○ Bipedal

○ Extended growth in males

★ Paranthropus boisei 

○ Hyperrobust

○ Kenya, Tanzania (Olduvai, Gorge), Ethiopia

○ Ate seeds, tubers, roots

★ Homo habilis/rudolfensis 

○ Found in association with Oldowan tools

○ Once thought to be first makers of mode 1 tool technology (but not the first ones to use tools)

○ Sexual dimoprhism

OR

○ Taxonomic diversity?

○ Homo rudolfensis

○ Olduvai Gorge, Tanzania (east Africa) in the 60s, 70s

○ Found throughout East and South Africa

○ 1.4- 2.3 mya

○ Australopithecus limb proportions

○ Larger brains (775 cc)

○ Smaller teeth

Pleistocene (about 12,000 to 1.8 million years ago)

★ Homo ergaster/erectus 

○ Some refer to them differently

■ Asian fossils= Homo erectus

■ East African fossils = Homo ergaster

○ Discovered in late 1800s by Eugene Dubois

○ Differences between H. ergaster

■ Thicker skull

■ More massive face

■ More pronounced occipital torus and brow ridge

■ Sagittal keel

○ Stone tools: Oldowan stone tools

■ Mode 1 in most localities

○ Evovled from early homo

○ .6-1.8 mya

○ Continued trend of larger brain, smaller back teeth, less facial prognathism ○ Primitive

■ Postorbital constriction: narrowing of the area behind the eyes ■ No chin

■ Receding forehead

○ Derived

■ Less prognathic

■ Larger brain

■ Smaller jaws and teeth

○ Unique traits

■ Perhaps related to novel tearing and biting forces in skull

● Brow ridge: bony buttressing of bone over the eyes

● Occipital torus: bony buttressing on back of skull

○ Morphology-

■ Most of what we know comes from KNM-WT 15000 “Turkana boy” ■ Almost complete skeleton that was discovered in mid 80’s

■ Lived 1.5 mya

● Modern body proportions

○ Long legs and relatively short arms

○ Narrow hips, barrel chest

○ Not arboreally adapted

○ Reduced sexual dimorphism (but more than modern

humans)

● Long distance runner?

○ Long legs, narrow hips, barrel-shaped chest, possible

projecting nose for moisture retention, possible hairless

body

■ Language limited?

● Maybe lacked fine motor control of the thoracic muscles

necessary for language?

BUT

● Language does not fossilize and finding evidence is difficult and controversial

○ Homo ergaster is thought to be the first hominin to leave Africa! ○ Meat Eating

■ Regular bone layering → irregular bone layering

● Vitamin A poisoning from eating carnivore liver?

■ Tooth: not well adapted to eating plant food, incisors adaptive for tearing and pulling meat?

○ Eventually invented mode 2 Acheulean stone tools

■ 1.4-1.6 mya

■ Biface

■ Specifically designed (carcass processing?)

■ Unchanged for 1 million years

Questions:

○ Hunting or scavenging?

■ Cut marks do not equate to hunting

● Hominins too small and too poorly encephalized to hunt

● Scavenging- probably both

○ Fire?

○ Cooking Food?

★ Homo heidelbergensis 

○ Larger brain

○ Larger brow ridge

○ No chin

○ Prognathic face

○ Large game hunting

■ Spears

■ Butchered animal bones

○ Diversity of food resources

○ Mode 3 technology

■ Levallois prepared core technique

○ Likely evolved into Neanderthals in Europe

■ Fluctuating environment

■ Cooling trend

■ Eurasia

● Frigid grassland

● Many large mammals

○ Evolved into Homo sapiens in Africa (the ones that stayed in africa) ■ 200,000 years ago

■ Fossils in Tanzania, Ethiopia

★ Homo neanderthalensis 

○ Larger brain (larger than Homo Sapiens)

○ Oblong Skulls

■ Occipital bun

■ Thin walled

○ Unique Teeth

■ Taurodont roots

■ Heavily worn incisors

○ Postcrania

■ Short and stocky

■ More robust limbs with better developed muscle attachments ■ Wide torso

■ Short arms and legs

○ Short lifespan

○ Difficult lives:

■ Arthritis

■ Gum disease

■ Injuries

■ Conspecific care?

★ Homo floresiensis “the hobbits” 

○ Flores, Indonesia

○ 16,000-74,000

○ Years ago

○ Small bodied (3ft tall)

○ Small brained

○ What is it?

■ Ancestral lineage of early Homo?

■ Island Dwarfism of Homo erectus?

■ Diseased Homo Sapiens?

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