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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 172 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 We also discuss several other topics like What is an absolute advantage?

○ 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 We also discuss several other topics like What are age and sex structure?

● 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

○ 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 We also discuss several other topics like What is linear electron flow?
We also discuss several other topics like How does the federal reserve affect monetary policy?

○ 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

○ 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 If you want to learn more check out How are health and education related?

● Turkana boy

○ Nearly complete skeleton of a 12 yr.old who was discovered by Lake turkana ○ Was part of Homo ergaster

○ 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 If you want to learn more check out What is hund's rule?

2. Energetics:

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

● 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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