Biological Anthropology Final Exam!

hominins

humans and their extinct ancestors

homonids

great apes

gene regulation

creates a key difference between humans and apes - overall 98.6% genetic match otherwise

unique hominin traits

• bipedalism

• material culture (i.e., art, writing)

• increases brain size

• long developmental period and life span

• unique dentition

mosaic evolution

different traits evolve at different points in time (i.e., hominins likely developed modern dentition and bipedalism first)

hominin dentition

• 2123 dental formula

• 32 teeth + wisdom teeth fluctuations

• Y-5 molar pattern

• canine reduction - less sexual dimorphism

• rotary chewing/mastication

• parabolic dental arcade

anatomy of brachiation and climbing

• increased mobility of arms and legs

• shoulder blade on the back

• long forelimbs compared to hindlimbs

• long curved fingers

  • stable wrist joints for knuckle walking

intermembral index

• (forelimb/hindlimb) x 100

• how long your arms are compared to your legs

• Lower in humans (longer legs) - 70%

• Higher in chimps (longer arms) - 110%

center of gravity - anatomy of bipedalism

center of gravity = middle (energy efficient for standing)

foramen magnum - anatomy of bipedalism

foramen magnum position - directly under the skull in humans

body proportions - anatomy of bipedalism

body proportions - lower intermembral index

vertebral column - anatomy of bipedalism

vertebral column - S-shaped spine holds the center of gravity in the middle.

pelvis shape - anatomy of bipedalism

pelvis shape - wide, basin-shaped in humans, with curved iliac blades that reposition gluteal muscles (stability)

knee - anatomy of bipedalism

knee - valgus angle ensures the foot is below the center of gravity

foot - anatomy of bipedalism

foot - enlarged heel, arch development, and big toe larger and not opposed

Miocene

age of apes and earliest human ancestors

Oligocene

anthropoids (parapithecids, propliopithecids)

Eocene

earliest definite primates (adapids, omomyids)

Paleocene

possible primate ancestors (plesiadapiforms)

rift valley

occurs at tectonic plate boundaries (i.e., Great Rift Valley in East Africa)

Sahelanthropus tchadensis - probable hominins

• 7-6 mya

• Chad

• smaller canines

• no cp-3 honing complex (shearing teeth)

• position of foramen magnum suggests bipedalism

• primitive brain size and dental arcade

Orrorin tugenensis - probable hominins

• 6 mya

• Kenya

• Femoral morphology suggests bipedalism

• Dental morphology is ape-like

Ardipithecus ramidus (+ kadabba) - probable hominins

• Ramidus - 4.4 mya

• Kadabba - 5.2 - 5.8 mya

• Ethiopia

• intermediate canine size (between human and ape)

• famous case - “Ardi” (ramidus)

Bipedal traits in Ardipithecus ramidus

• foramen magnum position

• S-shaped spine

• equal arm and leg length - intermediate between humans and apes

• Pelvis = mix for both climbing and walking (short, broad ilium)

Ancestral traits of Ardipithecus ramidus

• small brain

• prognathism

• divergent big toe

Derived traits of Ardipithecus ramidus

• reduced canine size

• no cp-3 honing

• low sexual dimorphism

• Lacking features for knuckle walking and suspension

australopiths (East and South Africa)

australopithecus (gracile) and paranthropus (robust)

Australopiths trends

• dentition - reduced canine size, larger cheek teeth, thick enamel

• Bipedal locomotion

• Smaller brain size

• Smaller than modern humans

• More sexual dimorphism

Australopithecus anamensis

• 4.2-3.9 mya

• Kenya and Ethiopia

• Derived traits = reduced canines, larger molars, thicker enamel

• bipedalism (earliest undisputed evidence)

• Primitive traits = U-shaped dental arcade

Australopithecus afarensis

• 3.9-2.9 mya

• East Africa - Kenya, Tanzania, and Ethiopia

• Famous case: “Lucy” - Dikka, Ethiopia; 3.3 mya; approx. 3 years old

• diverse habitats

Primitive traits - Australopithecus afarensis

• sagittal crest

• small brain

• prognathism

• sexual dimorphism

• climbing mobility/length in arms

Derived traits - Australopithecus afarensis

• smaller, human-like teeth

• bipedalism - valgus knee, non-opposable big toe, arches, enlarged heel, forward placed foramen magnum, short toes, and short, broad pelvis with curved ilium.

• Laetoli, Tanzania - Australopithecus afarensis footprints (3.6 mya)

Australopithecus africanus

• 3.5-2 mya

• South Africa

• Famous case - Taung child (endocranial cast)

Female skull traits - Australopithecus africanus

• slightly enlarged brain

• less prognathism compared to afarensis

• less developed nuchal crest

• reduced anterior dentition

Male skull traits - Australopithecus africanus

• cheek bones swept forward

• robust mandible

• larger cheek teeth

• thick molar enamel

Australopithecus sediba

• 2 mya

• South Africa

• Australopith traits = small brain and body size, and long upper limbs

• Homo traits = projecting nose, smaller teeth, chewing muscles, longer legs, and precision grip in hands.

Paranthropus general traits (robust australopiths)

• very thick enamel

• enlarged posterior teeth

• flatter face (orthognathic)

• sagittal crest

• flared zygomatics

• optimized for chewing

• extinction due to niche overlap and competition with Homo.

Paranthropus robustus

• 1.5-2 mya

• Southern Africa (Blauuwbank Valley)

• First Paranthropus ever found (1938)

• Open, arid habitats

• least robust paranthropus

• Post-canine megadontia - molars and premolars are larger

• similarities to Australopithecus africanus (single species hypothesis, sister taxa, etc.)

Paranthropus boisei

• 2.3-1.2 mya

• Eastern Africa

• Mary Leakey in Olduvai Gorge, 1959 (important find for further research methods and funding)

• most robust Paranthropus species

Traits - Paranthropus boisei

• Large back teeth + small canines

• Sagittal crest

• Flared zygomatics

• Small braincas

• Enlarged mandibular corpus and ramus (jaw)

• relatively high sexual dimorphism (size-related)

Homo traits (compared to Australopiths)

• East and South Africa

• earliest = Homo habilis

• increased brain size

• gracile cranium

• increased capacity for toolmaking - Oldowan

• decreased prognathism and postcanine size

• larger body size

• early homo = more similar to Australopiths than humans

Homo rudolfensis

• 2.4-1.6 mya

• larger brain size

• Australopith-like broad midface

• larger molar teeth

• developed mandible (chewing muscles)

Homo habilis

• 2.4 – 1.4 mya

• smaller brain size

• Broader upper face than midface

• Smaller molars

• Less robust mandible

• More australopith like limb proportions

Oldowan Tool Industry

• 2.6 mya – 200 kya

• Early Stone Age/Lower Paleolithic

• Cores = lumps of stone

• Flakes = fragments removed from cores

• Hammerstones = rounded stones used to remove flakes

• Used for butchering, plant processing, and wood

Swartkrans, South Africa - Toolmaking

• 1.8-1 mya

• digging tools found with polished bone and horn core

• Homo or Paranthropus

Bouri, Ethiopia - Toolmaking

• 2.5 mya

• Percussion & cutmarks on bone

• No tools found

• Australopithecus garhi

Dikika, Ethiopia - Toolmaking

• 3.39 mya - earliest evidence of tool use

• Cutmarked bones

• Not found in association with hominins or tools

Lomekwi, Kenya - Toolmaking

• 3.3 mya

• stone tools found

• Well before the earliest Homo

Chimp tool use

• Nut cracking

• Stone tool use

• Stone transport (<2km)

• Stone selectivity

• Small game hunting

Human tool use

• Stone transport >10km

• Stone tool manufacture

• Using tools to make tools (woodworking)

• Plant processing (USOs)

• Large game acquisition, carcass processing

Homo naledi - “weird” species

• Age unknown

• South Africa

• Remains (bones) from 15 individuals - largest collection from a single species

• Rising Star cave system

• Australopith traits - Small braincase; Ribcage, shoulders and pelvis similar to australopiths; Curved fingers

• Homo traits - Larger body size (adult males about 5 feet tall); Human-like feet; Small molars (but other details of the dentition more primitive).

Homo erectus/ergaster

• 1.8 mya - ~30 ka

• Erectus = outside Africa

• Ergaster = in Africa

• The first hominin with body stature and limb proportions similar to modern humans

• Out of Africa - Europe, Asia, and Java (South Asia).

• Oldowan and Acheulean tools

• Famous case - Turkana boy (ergaster fossil found in Africa)

Pliocene

• split between paranthropus and homo from australopiths due to differing niches

• Exposed land bridges due to colder climates and dropping sea levels

Homo erectus/ergaster traits

• No chin

• Sagittal keel

• Thick brow ridge

• Long, low, and flat cranium (football shape)

• less prognathic

• Protruding nose

• Smaller teeth

• Larger breen

• modern human legs and feet

Acheulean tool industry

• 1.6 mya - 200 ka

• more sophisticated

• symmetrical, biface tools

• standardized proportions

• Associated with big game hunting

• retouching - soft hammer percussion

Movius line

• separates erectus populations that developed Acheulean tools from those who didn’t

• Acheulean and Oldowan (Africa) vs. Oldowan (outside Africa)

Control of fire

• Homo erectus may have been the 1st species to control fire

• flints, hearths, and burned grass present at GESHER BENOT YA’AQOV, ISRAEL (790 ka)

Homo floresiensis - “weird” species

• 100-60 kya

• Liang Bua Cave, Flores, Indonesia

• No land bridge connection - need boats

• Australopith-like brain size and wrists

• About 3.5 ft tall

• Flat feet and long curved toes

• Evidence of fire and tool use

• Insular dwarfism?

Insular dwarfism

reduction in size of large animals when they get isolated in small habitats (islands)

Middle Pleistocene hominins

• 800-150 kya

• "archaics”

• One (heidelbergensis) or three species (heidelbergensis, antecessor, rhodesiensis)?

• Some archaic traits (i.e., large brow ridge)

• Larger cranial capacity

• smaller molars

Sima del Elefante - Middle Pleistocene hominins

• 1.3 mya

• Homo sapiens

• first Europeans

• Oldowan

Gran Dolina - Middle Pleistocene hominins

• 850-950 ka

• Homo antecessor

• Oldowan

• Cannibalism

Sima de los Huesos - Middle Pleistocene hominins

• 400 kya

• Homo heidelbergensis

• Pit of bones

Early Stone Age/ Lower Paleolithic tools

Oldowan (Mode 1) & Acheulean (Mode 2)

Middle Stone Age/ Middle Paleolithic tools

Mousterian (Mode 3) - Prepared core technology

The Late/Upper Pleistocene

• 159-40 kya

• Colder and drier

• Caves as shelter

Homo neanderthalis

• 150 - 27 kya

• inflated cheeks

• occipital bun

• retromolar space

• no chin

• large brow ridge

• large nose

• prognathism

• large cranial capacity

• robust and muscled body

• Mousterian tools

• modern behavior (i.e., ritual burials, elder care, art, etc.)

Late Stone Age/ Upper Paleolithic tools

Aurignacian (Mode 4) - Blade-based

Denisovans - “weird” species

• ~40 kya

• Southern Siberia

• genetically distinct from neanderthals

• only finger bone and teeth fossils + DNA

Homo sapiens

• Anatomically modern humans/homo sapiens (AMHS)

• primitive traits

  • Large brains

  • Flat face

  • Manufacture and use of tools

• derived traits

  • Rounded brain

  • large forehead

  • Chin, Small brow, teeth, face

  • Decreased robusticity

• First AMHS from Africa - Ethiopia and Morocco

• Aurignacian tools

Homo sapiens behavioral adaptations

• Projectile technology

• Fishing

• Personal adornment

• larger social networks/exchange networks, as evidenced by beads

• Belief systems? (burial with grave goods)

• Art (music, sculpture, rock art, etc.)

• More varied diet, which also included use of aquatic resources

• Longer settlements and shelters

Footprints from White Sands

• ~22 kya

• New Mexico

• Humans migrated to the Americas even earlier

Multiregional model - Models for AMHS origins

• Pleistocene hominins represent a single evolving lineage across different regions

• AMHS evolved in the context of significant gene flow between regions

Out of Africa model - Models for AMHS origins

• AMHS originated in Africa and later dispersed to occupy the Old World

• No gene flow / interbreeding, but replacement of existing hominins

Assimilation model - Models for AMHS origins

• African origin of AMHS

• Varying degrees of interbreeding with existing populations

• Most evidence-based model

BRAINSTEM

Regulates many basic body functions

CEREBELLUM

Integrates sensory perception, coordination & motor control; learning new motor skills

Cerebrum (NEOCORTEX)

Higher cognitive functions-- sensory perception, spatial reasoning, memory, conscious thought, speech, language

FRONTAL LOBE

Many higher cognitive functions – emotional expression, judgement, “personality control panel”

PARIETAL LOBE

sensory information (i.e., touch, heat)

TEMPORAL LOBE

Primary auditory cortex, processing of semantics, long-term memory

OCCIPITAL LOBE

Primary visual cortex

Encephalization

• the proportional size of the brain relative to body size

• Human brains size is highly encephalized (More brain for body)

GYRIFICATION INDEX

• The degree of folding of the cortex

• Ratio of total cortical surface to outer cortical surface

• Increases with brain size

Primary areas of the brain

basic functions, motor control and primary sensory processing

Association cortex

portion of the cortex that does not fall within primary motor and sensory areas (human brain has an increase in this area)

Cortical reorganization

humans have a relative decrease in primary areas and a huge increase in association areas

brain reorganization

Example in humans: olfactory is reduced while visual is increased

Cerebral Cortex

• Cerebral cortex surface is larger than expected for a primate of human brain size

• Non-uniform expansion of the cerebral cortex

• Prefrontal, parietal, and temporal areas have undergone the greatest expansion

Prefrontal cortex

• involved in decision-making, planning, working memory, and emotional regulation

• Expanded in apes in comparison with other primates.

• Humans show a further expansion of this area compared to apes

Characteristics of human language

• Voluntary and socially learned

• Semantic - Arbitrary symbols (words) convey meaning

• Phonemic - units of sound

• Syntax - rules and meaning

• Recursive - hierarchical structure

• Displacement - Ability to speak of things/events that are not present

Broca’s Area

Important for speech production

Wernicke’s Area

Important for speech comprehension

Language area asymmetry

In 95% of modern humans, language function is lateralized to the left hemisphere of the brain.

Anatomy of the Vocal Tract - language capacity

• Human larynx has a lower position compared to chimpanzees - more sound variety

• Human tongue differs in shape and forms the back wall of the oropharynx

• FOXP2 gene

‘secondarily altricial’

• humans as being born in a relatively helpless, immature state (altricial) compared to other primates

• reliance on parents

• fast post-natal growth

why ‘secondarily altricial’?

1) Bipedalism requires a pelvis with a narrow birth canal.

2) Due to metabolic constraints of gestation. Fetal metabolic requirements outpace maternal supply.

3) Selective advantages of extended neural development

Advantages of menopause

• Grandmothering Hypothesis = Inclusive fitness benefits are derived from older, non-reproductive adults who contribute to the care of their grandchildren.

Biomedical anthropology

• Evolutionary medicine - application of evolutionary theory to understanding health and disease

• Biological health disparities

• Genetic diseases

Forensic Anthropology

• Identification

• Cause of death