Human Origins Midterm 2 Review

Survey

walking across landscapes searching for fossils

Excavation

extracting fossils at flagged areas (from survey)

Cleaning

reconstruction; data collection; analysis of data

Total station

documents location of each artifact in coordinate space

Fossil

preserved remains of once-living organisms; inorganic; replacement of organic matter by minerals

Fossilization

the process by which buried tissues or forms of once-living organisms become preserved in non-organic mineral forms, typically taking in the thousands of years

Taphonomy

the study of changes that organic materials undergo between their death and recovery by researchers

Relative Dating

relative to something else

Absolute Dating

specific age (range) as provided by radiometric methods

Law of Superposition

relative; geological stratigraphy; things that are above other things are newer, things that are below are older

Biostratigraphy

relative; association with known fauna; relating to other living things

Radiocarbon Dating

can only be used to date organic samples, cannot radiocarbonate fossils. reliable up to 55,000 years because we know the rate at which carbon decays at

“radioactive clock”

we can get a good estimate for how long its been since the organism has died

Dendrochronology

tree-ring sequences; natural archive to know concentration of carbon 14 in the past

Electron spin resonance

absolute; used to date minerals like in tooth enamel and stone tools. radioactive clock from the time the material formed; effective up to at least 2 million years

Potassium Argon (K-Ar)

absolute; used to date igneous (volcanic) rocks; radioactive clock starts when the rock solidifes. much less precise but can be traced back much further.

Direct Dating

the chronometric date directly relates to the age of the sample

Indirect Dating

the chronometric date relates to the age of a sample that is somewhat associated to the sample of interest

Paleocene (65-55 mya)

first primates

Eocene (55-34 mya)

Adapoids/Omomyoids

Oligocene (34-23 mya)

first anthropoids (monkeys/apes)

Miocene (23-5 mya)

first hominoids (apes)

Pliocene (5-1.7 mya)

Hominins

5 derived traits of hominins (relative to extant apes)

1) obligate bipedalism
2) dentition and jaw differ (parabolic arcade, small canines)
3) relatively large brains
4) slow development
5) material and symbolic culture

Morphism: identifying bipedalism

• femur, tibia, and patella (knee-cap) shape

• pelvis shape

• foramen magnum (opening on underside of skull)

Proconsul

1st hominoid; shares traits with modern apes:

• no tail, forward facing eyes, smaller snout, larger brain, ancestral to chimp, gorilla, orangutan

3 theories for bipedalism as an adaption

1) Thermoregulation
2) Energy Conservation
3) Freeing Hands

Savannah Hypothesis

shrinking forests in late Miocene/early Pliocene led early hominins to increase time on the ground; thermoregulation idea; disproved because increased savannah area was not consistent.

S. tchadensis

• 7-6 mya, Chad

• Date based on associated fauna

• brain relatively small

• Evidence for bipedalism

• Debate over whether hominin/hominoid

Orrorin tugensis

• “original man”

• 6 mya, Kenya

• strong evidence for bipedalism

• morphology of hand phalanx and teeth (small molars, thick enamel)

• evidence as a human ancestor

Ardipithecus Ramidus

• 5.8-4.4 mya, Ethiopia

• small cranial capacity

• significant finding because of how complete it was

• mix of ape and australopithecine traits

• small

• locomotion - ardis foot and hand = facultive biped and arboreal clamberer, not a knuckle walker

• paleoenvironmental habitat - woods/forestm not desert

• small canines

What Ardi tells us about Human Origins

• modern apes evolved distinct social and locomotor behaviors IN PARALLEL; knuckle-walking is a derived trait

• bipedalism did not evolve in the savannah

Bipedalism / Brain size

among hominins, bipedalism is the more ancestral trait, large brains more derived

Lumpers vs Splitters

splitters - more labels/categories
lumpers - fewer labels/categories

Who are the australopithecines?

• group of hominins closely related (ancestral) to living humans

• “southern ape” but now known from east, south, and central america

Key features of australopithecines

• bipedalism indiicated by pelvic/leg/foot morphology

• large posterior teeth (molars/pre-molars) w/ thick enamel

• small anterior (incisors/canines)

• brain sizes still small

Australopithecus Anamensis

• oldest australopithecus

• 4 mya, kenya

• found in volcanic region

• larger canines/incisors than later hominins; ape trait

• parallel-ish tooth row; ape trait

• bipedal

• valgus knee (like humans)

A. afarensis general traits

• small cranial capacity

• prognathic

• post-orbital constriction

• reduced canines

• arm bones more similar to chimps

• lucy - famous, most complete example

Australopithecus africanus

• 3.3 - 2.1 mya south africa

• larger brain than a. afarensis

• rounder skull, smaller teeth than a. afarensis

• fossil “taung child” established importance of africa for hominin origins

Australopithecus Sediba

• 2 mya, in South Africa

• brain size similar to a. africanus

• possible tool user

Genus Paranthropus

• the robust australopithecus

• crania are far more robust; larger with denser bones

• pronounced sagittal crest

• large teeth

• 1) P. boisei (dead-end)

• 2) P. Robustus

• 3) P. aethiopicus; very large posterior dentition

Australopithecus and Paranthropus

• overlapped in time with genus Homo

• Relative to genus homo, they had smaller cranial capacity, larger prognathic faces, and postcranium somewhat adapted for climbing

• overall lived more like apes with faster growth

Homo Habilis

2.3-1.6 mya, kenya, tanzania, south africa
500-600 cc (up to 800?)
less post-orbital constriction
smaller teeth
shares more traits with australopithecus or humans?

Au Sediba

2 mya, South africa
cc similair to A africanus
larger body but similar proportion to australopiths
dental and facial features similar to genus homo
potential ancestor to genus homo
debate on being closer to H. sapiens than H. habilis

Relationship between H. habilis, H. rudolfensis, and Au sediba

1) These 3 species show mosaics of more “human-like” and more “Australo-pith” like traits. Their phylogenetic relationships have not been resolved
2) Most define genus homo by a shift to a larger brain size

Oldowan Tools: who made them?

H. rudolfensis, H. habilis, P. boisei, Au sediba

Oldowan tools: when and where

2.5 mya, Tanzania

Hypotheses for hominin lifeways

1) killer ape hypothesis
2) scavenging hypothesis
3) man the hunter hypothesis

Use-wear analysis of Oldowan tools

• butchering

• woodworking

• cutting soft plants

Oldowan Hominin Social Organization

• complex foragers and scavengers

• maybe some hunting

• little evidence for cooking

African Homo erectus when and where

east and south africa, 1.9 mya - 500 kya
700-1000 cc

African h. erectus ancestral traits

• some post orbital constriction

• receding forehead

African h. erectus derived traits

• less prognathism

• taller skull

• smaller jaw and teeth

H. erectus face and body

• external nose

• thick cranium

• large brow ridge

• humanlike limb proportion

• humanlike gait

Born to run idea

argument that adaptation for endurance running is key to genus homo

H. erectus lifeways

• new tool technology (better processing of carcasses and sporadic hunting)

• fire for warmth, protection, cooking

• humans as obligate cooks starting around H. erectus

• ate varied diet of plants and meat

• social groups living and working together

Achulean tools

• first appear 1.75 mya

• some argue they are too large to be functional

• hominins CONTINUE making oldowan tools

• better processing of carcasses/sporadic hunting

H. Erectus Moving

H erectus is first hominin to move out of Africa
H. erectus-like species in Republic of Georgia

pre-H erectus hominin left Africa first?

more ancestral features

Why did they leave Africa?

• climate change grasslands shifting northward, game follow grasslands

• hominins follow game or seek more favorable climate

African H Erectus vs Asian H. erectus

Africa H. Erectus has thick cranium, large brow ridge, and 900-1000 cc.
Asian H. erectus is more recent, has thick cranium larger brow ridge than African H. erectus, 1000-1250 cc

No Achulean tools in East Asia

• H. erectus in e. asia continued only oldowan tools

• boundary: movius line

H. erectus in china

zhoukoudian cave significant because it has hundreds of tools, deposits are very deep

Homo floresiensis

• 190-50 kya, Indonesia

• small body

• 400 cc

• initially thought to be H. Erectus child or adult with disability

• similarity to H. erectus
  
  

Floresiensis lifeways

• oldowan tools

• hunters (giant rats)

• defended against predators

• did NOT use fire

• adapted more for walking than running

Why was H. floresiensis so small?

• Innviar island dwarfism: isolated island populations

• or descended from smaller-bodied hominin

Floresiensis extinction

• occurs around time H. sapiens arrive on Flores

• genetic drift in small population led to genetic disease

• no evidence that H. sapiens and H. Floresiensis interbred

H. Heidelbergensis

• 800-500 kya, Zambia

• one of several types of middle pleistocene Homo

• large brow ridges, no chin

• 1280 cc

• rounded occipital

• evidence for big-game hunting (wooden spears)

• possible common ancestor to humans and neanderthals

Sima de los Huesos

• spain site with hominin bones

• individuals foreshadow neanderthals

• largest cranial size

• occipital bun

• wide nasal apperture

• midfacial prognathism

• no chin

Lifeways of Sima de los Huesos

inhabitants

• dental abscesses

• periodontal disease

• most cranial individuals with postmortem breaks

• but about half show perimortem breaks, maybe from murder or free fall

Homo naledi

• 330-230 kya, South Africa

• Mosaic of traits with Australopiths and Humans

• Australopithecus-like pelvis and shoulder

• legs, hands, and feet more like later Homo

• smaller teeth but very strong enamel

Rising Star Cave

• naledi remains found

• no tools or animal bones

• underground astronauts

Discovering the neanderthals

• Germany

• officially recognized human ancestor

• long before africa recognized as cradle of humankind

Cro-Magnon / Archaic H. Sapiens

term describes early Homo sapien inhabitants of europe

Neanderthal Cranial Traits

• large braincase 1500 cc

• large brow ridge

• occipital bun

• long skull, football like shape

• wide nasal apperture

• mid-facial projection

Neanderthal Dentition

• small posterior teeth, large anterior teeth

• jaws did not shrink as fast as molars, leading to retromolar gap

Neanderthal facial traits

• no chin

• low forehead with heavy brows

• large nose

• large mid-face

Neanderthal Postcranial traits

• extremely robust

• barrel-chested, heavily muscled

• short and stocky

• wide pelvises

Cold climate adaptations for neanderthals

• lived in northern regions during pleistocene

• more body surface area = more heat loss

• stockier body type means more heat retention

Other neanderthal adaptations

• posterior brain expansion = better visual system for dark winters and high latitudes

• large nose/barrel chest = more airflow for larger bodies

Mousterian tools

• made with Levallois technique (complex technique)

• found widely at neanderthal sites, also probably made by homo sapiens

• primarily made with hammerstone

• percussion tool making

Hafting (spears)

• mousterian points very sharp, so good for spears

• technological advancement for game hunting (improves on all wood Schoningen spears by H. heidelbergensis)

Neanderthal genome

• ancient DNA from full neanderthal genome successfully sequenced

• DNA begins to degrade after organism death and decompositions from microorganisms and temperature changes

• contamination is a major concern in sequencing neanderthal DNA

• Neanderthal DNA made to be readable

Neanderthal DNA findings

• low genetic diversity in later population history due to small population sizes and mating events between close relatives

• population bottleneck; glacial advances and retreats

DNA Evidence: humans and neanderthals

• genetically distinct from homo sapiens

• late Pleistocene populations of homo sapiens and neanderthals interbred in Europe and Asia

FOXP2 gene

• possibly linked to language but specific role unknown

• derived form is shared between homo sapiens and neanderthals

Neanderthal language

• have similar hyoid bone to humans (used in speech)

• no strong evidence of language

• other options include more apelike spoken language, some type of sign language

Denisovans

• last, kind of mysterious hominin

• finger bones discovered in Denisova cave in Siberia

• genetically distinct from neanderthals buried in the same cave

• first hominin identified on genetic differences and not morphological

• no official species name

Newer denisovan discoveries

• newer finds in China, Laos, Taiwan

• divergence from common ancestor with neanderthals ~550 ya

• lived 130-75 thousand years ago

Who were the Denisovans?

• some already known fossils may be Denisovan

• “homo longi” was first denisovan cranium found 2021

Denisovan Lifeways

• possible evidence of high-altitude adaptations

• new research suggests they hunted and consumed herbivore meat (tool use?)

• interbred with homo sapiens and neanderthals

Why term “cave men” used

• many discoveries made in caves

• natural form of shelter, probably used for habitation sometimes

• protects ancient remains (bones)

• allows for preservation of ancient DNA

Neanderthal intelligence and brain size

• larger brains than homo sapiens but not necessarily more intelligent

• larger body sizes overall

• compared with homo sapiens, had larger visual cortex

• neanderthal brain region variation still within range of homo sapiens

Neanderthal lifeways

• proficient hunters of large mammals

• they were not opportunistic scavenging

• targeted particular species and hunted animals in their prime

• behavioral adaptations to local environments

Neanderthal dental calculus

• hardened plaque that preserved food and microorganisms

• found wild sheep, rhino, nuts, moss, etc.

• neanderthal teeth from spain show no evidence of meat

Neanderthal mortality rates

• found specimen assigned to age classes

• age estimation through dentition, bone epiphyses, and cranial suture closure

• more neanderthals died as young adults

• patterns of bone breakage

• many healed trauma present in upper body, less in lower limbs

• neanderthals had risky lifestyles and were dying younger than homo sapiens

Neanderthals vs Modern groups

• neanderthals and rodeo riders

• similar to upper paleolithic modern humans

Shanidar cave

• found individuals with many traumas and fractures

• some shanidars lived with disabilities

• shows that this was a society where people were looking after each other

La Chapelle-aux Saints, France

• “old man'“ famous neanderthal fossil

• similarly had a lot of injuries

• intentional burial is sign of society with social networks and respect for the elderly

Neanderthal burials

• only extinct hominin with good evidence for intentional burial of dead

• suggest symbolic and abstract thought of death, possibly places of remembrance

• possible evidence for grave goods but unclear what their role is/was

Shanidar Cave “flower burial”

• discovery of flower pollen in Shanidar 4 burial

• used as evidence of flower bouquet honoring the dead

• but debunked in 2023 and more likely local flower pollen brought by burrowing bees