Anthro 101: Human Biological Evolution

Lecture 12: Origins of the Modern Human Lifestyle – Neandertals & Modern Humans

Using modern foragers as a model to understand the importance of complex foraging technologies

Humans rely more on foods that are hard to get than other apes do

Human foragers use wide range of prey and techniques

• Prey• Mammals, birds, reptiles, fish

• Techniques are variable• Prey type• Season• Snares, traps, calls, tracking• cooperation

• Processing• Butchery• Smash bones• Cook• Process plant foods too

Obtaining extractive resources requires skill, strength, and detailed knowledge

For humans, foraging technology takes years to learn

Complexity of foraging tasks may favor bigger brain & slower development

• Learn skills & knowledge• long period of learning• Long period for practice

Favors• larger brain• Slow development • Longer reliance on parents

Long juvenile period longer life span

• Delays start of reproduction

• Invest in growth & learning

• Payoff greater if allowed to

accumulate RS over longer

life span

• Longer lifespan means

bigger payoff for early

investment

High skill tasks favor division of labor and food sharing• Foraging tasks hard to master ==> specialization• Specialization ==> food sharing• In modern foraging societies

• Women mainly forage• Men mainly hunt

Resource exchange is extensive in human groups

Sex differences in food production and consumption among the Aché (Paraguayan rainforest)

Among modern humans: men commonly share with woman & his children

Meat is a high-variance food source• Meat is a high-quality food source: vitamins, protein, fat• However, meat is a food source with highly variable returns:

Requirements for successful reliance on high variance food: Reciprocal Altruism

• Live in large enough groups of hunters to reduce risk and have enough sharing partners

• Have cognitive skill to keep

track of partners & history of

sharing

• Be able to prevent people

from taking and not giving

• In modern hunting societies,

riskier foods shared more

widely

Food sharing + division of labor may favor reduced sexual dimorphism

• Men produce extra calories

• support a women & their kids

• If kids need males’ contribution

• selection favors investing males

• selection favors male-female bonds

• Reduced male-male competition

• Favors reduced sexual dimorphism

Efe man with newborn

What does this tell us about foraging in the Pliocene era?

• Contemporary foragers rely on complex foraging

• Complex foraging linked to important features of human life

history

• Did Oldowan toolmakers have complex foraging strategies?

• Toolmaking suggests they at least began to

• First step in transition from ape-like hominins towards

more human-like hominins

• Morphology and behavior of later species can be explained

by this innovation

Did H. erectus have a more modern human lifestyle?

• Reduced sexual dimorphism (Yes)• Less male-male competition?• Reduced polygyny, tendency toward pair bonds?

• Infant (& adults) brains larger than earlier species (Yes)• Altricial infants - dependent on parental care• Rapid brain growth after birth, slower maturation rate (Yes)

• High energy demand on mothers from altricial infants• Selection for paternal investment?• Selection for menopause & female-female cooperation?

The transition to (later) Homo marked by:

• Increased reliance on hunted meat and extracted foods

• Greater reliance on (more complex) tools

• Longer juvenile period to learn foraging and tool use techniques; longer life span

• Greater paternal investment increased pair bonding, reduced dimorphism

• Origins of transmitted culture (eg foraging & tool making techniques)

Complex foraging a major part of later hominin evolution

• The genus Homo is marked by:• More hunted meat and extracted foods• More complex tools crucial for survival• Longer juvenile period

• learn foraging and tool skills• longer life span

• Greater paternal investment

increased pair bonding, reduced dimorphism• Origins of transmitted culture

• foraging techniques• possibly language

Definite Homo species

• Homo ergaster• Homo erectus• Homo floresiensis• Homo heidelbergensis• Homo neanderthalensis

• Denisovans• Homo sapiens

New Dmanisi skull may alter how we identify speciesduring this time period!

Transition to later Homo occurred between the Pliocene & the Pleistocene @ 1.8 mya

Upper

Lower Pleistocene Middle

1.8 mya .9 .3

Upper

Sharp cooling trend

Glaciers cover much of Europe

Major climaticfluctuations

The shift towards more modern Homo begins about 1.8 mya (not modern humans yet)

• Hominins in Africa with:• Skull similar to earlier hominins• Taller body • Long legs and short arms• Slower growth rate, longer

childhood• Reduced sexual dimorphism • Made Mode 2 tools

• Acheulean hand axes

H. ergaster KNM ER 3733

The shift towards more modern Homo begins about 1.8 mya (not modern humans yet)

• Similar finds in C. Africa, S. Africa, Asia• first hominin found in Asia

• Classified as Homo erectus or ergaster

• We will call them erectus, but• earlier forms in Africa

sometimes called ergaster • later forms in Asia sometimes

called erectusH. ergaster KNM ER 3733

Homo erectus combined ancestral and derived traits

• Ancestral features• receding forehead• no chin• narrowing behind eyes

• Post-orbital constriction

Dmanisi

KNM-ER 3733

Homo erectus combined ancestral and derived traits

Derived features• Occipital torus• Thick brow ridges• Thick skull • Smaller, less protruding face• Higher skull• Smaller teeth• Sagittal keel• Shovel-shaped incisors• Large orbits• Wide lower skull• Brain size ranged from 700 - 1200

cc

KNM-ER 3733

Some derived features of skull linked to diet(?)• All teeth smaller, especially molars

• tearing and biting with canines & incisors• Occipital torus & brow = thick ridges - buttress

• chewing and biting strength• NOT muscle attachments

• Sagittal keel?• Shovel-shaped incisors indicate heavy use of teeth

P. boisei H. erectus

Shovel-shaped incisors

Krapina Neandertal maxilla K, photograph © Milford Wolpoff

Post-cranial skeletons tell us a lot about H. erectus

• Nariokotome boy - East Africa• Most complete skeleton

• Tall adults (male 6’, female 5’)• Long limbs• Narrow hips

==> infants born with small brains, slow development

• Tooth age indicate faster maturing than modern humans, though

• Narrow shoulders• Thick bones ==> heavily muscled• Sexual dimorphism reduced, still > Hs Body proportions like modern humans in

tropics KNM-WT 1500

H. erectus mastered new subsistence skills• First (so far known) to leave Africa• More complicated stone tool kit - Acheulean tools• Controlled fire (possibly very early, definitely later) 1-2 mya• Relied more heavily on hunting - ate more meat

H. erectus 1st hominin to leave Africa in Lower Pleistocene

1.8 mya

1.7 mya

1.8 mya

Why now and not earlier?

Technologically more advanced

• 1.8 mya using Oldowan tools• 1.7 - 1.4 mya bifaces added to toolkit

• Bifaces = round cores shaped to make flatter with longer cutting edge all around• Hand axe & cleaver

• Acheulean = Bifaces = Mode 2• Acheulean + Oldowan = Early Stone Age

Hand ax

Cleaver

Hand axes reveal something about minds and habits

• All have same Height:Width:Thickness proportions • Unchanged for 1.5 million years

• common plan in heads of toolmakers• Used for specific purposes in standard ways• Knowledge passed along by teaching and imitation

Hand axes probably used to butcher carcasses

• well suited for cutting, dismembering animal carcass• Wear patterns support meat processing• Pointed end cuts through meat, rounded end fits in palm

• Flakes maybe also used for cutting• Biface holds sharp edge longer than flakes• Longer cutting edge than a flake

Late Homo species

• Homo ergaster• Homo erectus• Homo floresiensis• Homo heidelbergensis• Homo neanderthalensis

• Denisovans• Homo sapiens

Complex foraging a major part of later hominin evolution

• The genus Homo is marked by:• More hunted meat and extracted foods• More complex tools crucial for survival• Longer juvenile period

• learn foraging and tool skills• longer life span

• Greater paternal investment

increased pair bonding, reduced dimorphism• Origins of transmitted culture

• foraging techniques• possibly language

Major climatic changes occurred during Pleistocene

Lower Pleistocene Middle

1.8 mya .9 .3

Upper

Sharp cooling trend

Glaciers cover much of Europe

Major climaticfluctuations

Homo erectusHomo heidelbergensis

Homo neanderthalensis

Middle Pleistocene

(900 – 300 kya)• Long, cold glacial periods• Short, warmer interglacial

periods

• Great variability in climate• Next stage in hominin

evolution occurred during this stage• More like modern humans

than Homo erectus

Figure 13.12a

Figure 13.12b

Emergence of modern features begins with H. heidelbergensis (approx. 800kya)• Ancestral features

• Large brow ridges• Thick cranial bones• Large, prognathic face• No chin• Robust bodies

• Derived features• Brain size 1200-1300 cc• Higher foreheads• More rounded skull• Sides of skull more vertical

H. Heidelbergensis identified as a new species of hominin (by some)

• More Derived features (compared to H. erectus)• Less prognathic• Smaller teeth• Smaller brow ridges,

one over each eye• Flexed base of skull• Reduced postorbital

constriction• Rounded occipital

bone

Bodo

H. heidelbergensis hunted big game

• On island of Jersey, piles of bones of mammoths and wooly rhino found at base of cliff• Some are adults, too big for most predators• Carcasses have been butchered with stone tools• Skull cavity opened, to extract brain tissue• Bones have been sorted by body parts

• Have also found wooden spears alongside masses of horse bones

H. heidelbergensis began making new kinds of tools

• Continued to make Mode 2 till 150 kya• Oldowan & Acheulean• cores flaked along sides to extend cutting edge • 300 kya, H. heidelbergensis started making flake tools

Mode 3

Levallois technique (Mode 3)• Involves striking flakes from a

prepared core• A striking platform is formed at one

end• Core's edges are trimmed by flaking

off pieces around the outline of the intended flake

• Large, symmetrical flakes are struck off of the core

• This method provides much greater control over the size and shape of the final flake

• More efficient use of available stone• Greater level of planning & abstract

thinking

A variety of tool innovations

Some of these tools were hafted • Wear patterns on tools

suggest some were attached to a handle

• Greater force & greater safety

• Spears

Lots of new materials and shapes• Soft hammers (bone, wood)• Retouched edges• Stylized tool shapes• Wider variety in toolkit

Social life of H. heidelbergensis

• H. erectus were hunters, also still scavengers• H. heidelbergensis were definitely hunters

• If their life was similar to modern hunting people, then:• Male-male cooperation during hunting• Sexual division of labor• Food sharing• Knowledge, skill, learning• Male aggressiveness (?)• Interdependence of men & women to raise children• Pair-bonding

• How well does the evidence fit the theory?

Social life of H. heidelbergensis• Group size calculated to 131 people

• As group size increases, takes more time to monitor relationships

• Intelligence & language could make this easier• H. heidelbergensis brain much larger than H. erectus• NOT clear WHY (social, ecological, technology)

• Do have more sophisticated tools

• What about language?

Physical adaptations for language

• Cranial base flexed• Longer larynx• Range of vowels

• Other species vowelsmore limited• Can produce nasally

• Mammals• Lower their larynx while vocalizing• Same freedom of movement to

produce range of sounds

Homo erectus language?

• Humans = flexed cranial base

• H. erectus = flatter • Short pharynx• Vowels limited

• Neanderthals also a bit flatter than modern humans

H. Erectus (java)

Physical adaptations for language

• Vertebral canals• Space in bone of vertebrae for nerves• Nerves in rib cage control breathing

• Chimps & some Homo erectus fossils have small openings• Suggest limited

breath control

• 2006 Dmanisi vertebrawithin modern humanrange

Homo erectus language?

• Dmanisi on left, similar to modern human canal• H. erectus from Kenya on right, smaller like a chimp canal

Possible Language in H. heidelbergensis

• Some evidence suggests could have used language• Breath control

• vertebral canals larer• Tongue innervations (lots of nerves to control it)

• canals in mandible & skull• Length of pharynx

• Flexed base of skull

Social life of H. heidelbergensis

• Male parenting & pair-bonding?• Large brain size, narrow pelvis• Altricial offspring take lots of energy• Females limited in foraging by offspring➔ Cooperation & division of labor necessary

• Male-male competition?• Evidence for cannibalism

• Bones processed same way as deer bones at site in Spain• Territorial aggression & eating of enemy? Eating own group

members?• Sexual dimorphism slight, like modern humans• Hunting large game with hand held spears…➔ Cooperation & sharing necessary

The Hominin lineage – 1.8 mya to present

• H. erectus --> H. heidelbergensis = 800 kya• Speciation & divergence in Africa• H. erectus survived in Asia• H. erectus extinct in Africa

• H. heidelbergensis the 2nd species to leave Africa• Southern Europe 800 kya, northern Europe 500 kya• India & China by 600 kya

• H. heidelbergenesis gave rise to:• H. Neanderthalensis 300-150 kya• H. sapiens 200 kya

H. heidelbergensis

H. floresensis

H. sapiens

H. erectus

H. Neanderthalensis

Around 300 kya, morphology of H. heidelbergensis in Europe began to change

• Site = Sima de los Huesos, Spain• 2000 bones from > 24 individuals• Unique skull traits

• Bulge in middle of face• Brow ridges arch over each eye• Skull with rounded back• Cranial capacity = 1390 cc

• Considerable variation in population

Homo neanderthalensis: 150 - 30 kya

• Distinctive features• Massive brows• Low forehead, long cranial vault• Very large face, mid-face bulge• Occipital bun at back of skull• Large, heavily worn incisors• Fused roots on molars• Shovel-shaped incisors• Short, muscular bodies• No chin• Gap behind 3rd molar

Neanderthals look like modern creatures in very cold places• Animals in cold places are large and stocky, with short limbs• Animals in hot places are smaller, thinner, longer limbed

M. fuscata, Japan M. sinica, Sri Lanka

People in warm climates tend to have long limbs in proportion to height

Neanderthals were short and stocky, but not stupid

• Cranial capacity ave. = 1520 cc

(modern humans ave. = 1400 cc)• Modern hyoid bone, language likely

Why such a prognathic face and big nose?

• Warmed air on intake?• BUT, modern populations in cold

climates have narrow noses• Stronger biting force?

• BUT, typically face is flatter in animals with strong bite force

• Genetic drift without adaptive purpose - most likely• Continues trend of larger faces seen

in archaic H. sapiens• Isolated population during glacial

periods• Genetic drift of genes for large faces

Neanderthals may have matured quickly

• Rate of enamel development on teeth• Faster in Neanderthals than humans• Neanderthals fully grown by 15 years old

• May have evolved to start reproduction sooner

• High adult mortality rate

Neanderthals were skilled toolmakers

• Made Mode 3 tools (Mousterian industry/ Levoillois technique)

• Continued to use Mode 2 (Acheulean tools)

• Wood spears• hafted spear points• Retouched edges

• Efficient use of stone• Large variety of tool types• Little bone or antler used at

most sites

Neanderthals hunted big game: diet high in meat

• Bones of red deer (elk), deer, bison, aurochs, goats, sheep, horses• At many sites, one kind of prey species predominates• Prime-aged adult prey common• Some sites at foot of cliffs have huge piles of bones• Chemical analyses of fossils = diet high in meat• Close-range hunting

Neanderthals buried their dead

• Lots of nearly complete skeletons

• Lots of children found• Maybe to avoid scavenging of

bodies, maybe held cultural significance

• Some controversial evidence of ritual or ceremony at burial

• Ochre?• Grave goods?• Fetal position?

Burials preserve rare skeletons of children

2-year old Infant

Neanderthal life was hard and short

• 40-45 years maximum lifespan• Many skeletons show evidence of disease, injuries

• Arthritis, gum disease, fractured skull & neck, stab wounds, withered limbs

• Run-ins with prey & predators?

Spear hole in skull Gum disease & missing teeth

Some Neanderthals survived serious injuries and illnesses

• implies that Neanderthals cared for the ill and injured

Neanderthals may have practiced cannibalism sometimes• Modern cannibalism = ritual• No ritual in Neanderthals• Krapina, Croatia - 130 kya

• Long bones cracked for marrow• Cut marks on some bones• Some bones burned

• France - 100 kya• 78 hominind bone fragments +

hundreds of red deer bone fragments• Lots of cut marks• Long bones broken = extract marrow• Deer and hominin bones treated the

same

Cut marks on skull from Krapina, Croatia

A beginning of art and modern culture?

• Red & yellow ochre• No representational carvings• Perforated & grooved animal bones

& teeth• Maybe art, maybe natural causes

• One site of Neanderthal remains + Chatelperronian industry 40 - 27 kya

• (usually modern human)• Bone tools• Carved bone pendant• Pierced bones & teeth• Blade tools• Shelter construction

A beginning of art and modern culture?• Shell jewelry found in Slovenia 50 kya

• Pierced, indicating worn as jewelry• Pre-dates arrival of modern humans• Evidence of pigment on shells - painted

A beginning of art and modern culture?

• Slovenia site 82 - 43 kya• Possible flute = Evenly spaced holes in bone• Or random gnawing and punctures by carnivores?

Second species of nearly modern humans

• Denisovans• Split from Neanderthal

lineage 350kya• Very large molars• Lived in Eastern Eurasia• DNA passed to modern

human populations in SE Asia

• 1 pinkie bone (40kya)• 1 molar

Neanderthals are NOT ancestral to modern humans

• Homo heidelbergensis 800 - 150 kya led to both…

• Neanderthals (Homo Neanderthalensis)• Limited to Europe & western Asia• 150 - 30 kya

• Homo sapiens (modern humans)• Separate species from Neanderthals• Overlapped in time with Neanderthals• Evidence for interbreeding & gene flow• Modern humans descended from group in Africa living

at about the same time as Neanderthals