Transcript PowerPoint

You are what you eat!
“The headhunter is not content merely to
possess the skull, but opens it and takes
out the brain, which he eats in order by
this means to acquire the wisdom and
skill of his foe”
GHR von Koenigswald
“Diet underlies many of the behavioural
and ecological differences that separate
species, and so is important in defining
niche, with all its implications for the
ecology and evolution of extinct forms”
Peter Ungar, 2003
Dr. Susannah Thorpe, Rm W126 Email: [email protected]
Homo erectus
• Glacial conditions
• Cave / sapling shelters
• Fire:
•
warmth
•
protection
•
cooking?
Chimpanzee diet
• Fruit, insects, leaves, bark, meat (monkeys,
pigs, small antelope)
• Hunting: mostly males, cooperative & specific roles
• Gombe – ca.150 red colobus monkeys killed during
peak hunting year
• Peak male chimp meat consumption near lower end of
human consumption (5-10% of diet)
• Excited by meat, crave it, chew it long and
thoughtfully, usually with a mouthful of leaves added
• Social event: shared between hunters/ kin/ allies
• Infanticide- Banana provisioning?
Chimpanzees: medicinal plants
• Medicinal plants: pith or leaves of plants with
medicinal properties
– know when they need it
– knowledge to select particular species that are not
part of normal diet
– Tongwa people eat the same plants for medicinal use
– unpalatable, chimps swallow them like pills rather
than chewing the leaves
– Contain an antibiotic against bacteria, viruses, fungi
and parasitic worms
Australopithecines
• Tooth shape evolves to improve mechanical efficiency for
chewing . - tooth morphology differs among species adapted
to different diets
• Teeth dominate fossil hominin assemblages
• Fossil hominin teeth generally very worn, - can’t use standard
measures for measuring cusp shape
A. Afarensis (top)
H. erectus (bottom)
Australopithecines: Topographic analysis
• Laser scanner - generate 3D points along the surface of a tooth
• Geographic information system (GIS) - model and characterize
the surface points
• Score teeth by wear stage - compare shape data among
similarly worn specimens of different species
(Unger 2004)
Australopithecines: Topographic analysis
Occlusal relief:
• high (h)
• low (l)
Cusp shape:
• sharp (s)
• round (r)
• blunt (b)
•  occlusal relief and steeper cusps  efficiency in fracturing
tougher, more deformable foods (leaves)
•  occlusal relief and  steep cusps  efficiency in fracturing
brittle, less deformable foods (nuts/seeds/hard fruits)
Australopithecines: Topographic analysis
A: gorilla
B: chimp
C: early Homo
D: A. afarensis
Gorilla gorilla have the steepest slopes and most relief  early
Homo  Pan troglodytes  A. afarensis which has the
flattest slopes with the least relief
(Ungar 2004)
Australopithecines: Topographic analysis
• Dental morphology reflects
adaptations to primary foods, and
also to less frequently eaten but
still critical ones
• Gorillas  occlusal relief and
steeper cusps  efficiency in
fracturing tougher, more
deformable foods (leaves)
• Both prefer soft fruits but gorillas
can take advantage of fallback
foods that are less accessible to
chimps
A: gorilla, B: chimp
Australopithecines: Topographic analysis
• A. afarensis:-  crown relief and  sloping occlusal surfaces
than gorillas or chimps
– more efficient fracture of brittle, less deformable foods but less efficient
fracture of tough, more deformable foods
•  preferred soft, sugar-rich fruits, but would have been able to
make better use of hard, brittle resources as fallback foods
given seasonal availability
of favored items
Gorilla gorilla (A)
Pan troglodytes (B)
Early Homo (c)
A. afarensis (D)
Early Homo: Topographic analysis
• Early Homo: intermediate bw chimps & gorillas in slope and
occlusal relief,  intermediate in the fracture properties of the
foods to which it was adapted
•   efficiency in fracturing tough, pliant foods than chimps or
A. afarensis
• + thinner enamel: sharp edges at sites of dentin exposure
with wear would improve shredding and slicing efficiency
• What tough foods were available to early Homo?
– Meat: tough and elastic. > occlusal relief and steeper sloped cusps
yield sharper cutting surfaces = reduces meats ability to stretch and
absorb energy,  thwarts major toughening mechanism
Paranthropus boisei
• Ungar: A. africanus & Paranthropus lived at
different times at Sterkfontein
• A. Africanus: steeper molar cusps
• Paranthropus: large, crushing teeth
(roots/seeds)
• Did climatic swings lead to reduction in food
sources for Paranthropus?
Did H. erectus hunt or scavenge?
• more food per square mile of the African
savannah than plant food
• more effective energy source
– venison: 572 cals per 100g
– fruit/veg <100 cals per 100g
• Reduced risk of seasonality, esp. in
Northern temperate zones
Zhoukoudian (China), 400,000ya ‘Peking man’
Ash, choppers, flake tools & fossilised remains of H. erectus
Cosy domestic scene, with H. erectus using fire for warmth,
protection and to cook meat
Did fire played a regular
or important role in the
daily life of the
inhabitants?
Zhoukoudian (China), 400,000ya ‘Peking man’
• Certainly some evidence of fire, but Lewis Binford :
– Many of the extensive ash layers may be results of the
decalcification of massive organic deposits (including bird
droppings, bat guana, hyena faeces)
– Fires could have been a result of the accidental ignition of the
organic material, which then smouldered for some time
• Binford found no hearths, or any association between
ash, stone tools and H. erectus fossils
• So although had all the ingredients of a cosy domestic
scene the ingredients were not related
Zhoukoudian (China), 400,000ya ‘Peking man’
• Little evidence of cooking food. A few burnt bones (2 roasted
horses heads), but other burnt bones had been meatless when
put in the fire:  caught up in smouldering organic material
• Binford et al:
– hyenas responsible for most of the materials in the cave
– H. erectus scavenged from hyenas – (hyena gnaw marks
underneath hominid stone tool cut marks on some bones)
a: hyena, b: stone tools
a
b
But,
• Stone tool evidence
– Schick & Toth: wear patterns & experimental studies Acheulean hand axes & cleavers were used for extensive
meat eating
• Anatomy (size and shape): Alan walker:
– H. erectus
• comparable to top 17% of modern human pop. in height
and mass
• anatomical stasis (early forms very similar to late forms)
• ca.1/3rd larger than H habilis and H rudolfensis
• Could scavenging really have brought about a change of this
magnitude?
Brain size vs. gastrointestinal tract
• H. erectus = 27-62% increase in brain
size compared to early H
• Earlier species had funnel shaped rib
cages and pot bellies like living apes
• H. erectus = probably first hominid type
to show a barrel-shaped thorax and a
distinct waist similar to modern humans
– significant decrease in size of
gastrointestinal tract
Mass-specific organ metabolic rates in humans
Brain: mass specific metabolic rate
c.9x average rate for body
Liver/gastrointestinal tract: mass
specific metabolic rate c.9.8x average
rate for body
2 ways to accommodate the increased
energy demands of the large brain of
HE:
• raise the overall basal
metabolism rate of the body or
• compensate for brain growth by
reducing the size of another
metabolically expensive organ
Organ
Metabolic
weight in W.
Kg-1 (watts
per kg)
Brain
11.2
Heart
32.2
Kidney
23.3
Liver & gastrointestinal tract
12.2
Skeletal
muscle
0.5
Lung
6.7
Skin
0.3
Organ weights
4500
4500
but we have much bigger 3500
brains and smaller
gastrointestinal tracts than 3000
expected
2500
The energetic savings from
2000
reducing the digestive
system c. = added cost of
1500
larger brain
1000
 beginning w. HE, humans
experienced an evolutionary
500
trade off of intestines for
brains
0
Brain
Brain
Gut
Gut
Liver
Liver
Kidney
Heart
Kidney
Heart
4000
4000
3500
Organ weight in grams
Humans = same standard
basal metabolism rate for
mammals our size
Observed human organ weights in
comparison to expected weights for
a mammal our size
3000
2500
2000
1500
1000
500
0
Observed Observed
Expected Expected
Dietary implications:
Food quality
Food quantity/
Intestinal
processing time requirements
poor quality (low energy) /
hard-to-digest (e.g. gorillas)
eat a lot
process it slowly
large stomach
and intestines
high quality (high energy) /
more digestible diets (e.g.
carnivores)
less food
smaller organs
for digesting it
• By hunting H. erectus accessed energy
rich food source
• Only hunting would have provided
enough & consistent protein for this to
take place
• Surplus energy was used to feed
hominin brains, which began to grow
significantly
Meat
eating
Brain
clever ways to
obtain more meat enlargement
How did they hunt?
• Methods to study early hominin behaviour
A
Living system
in the present
B
Contemporary
“fossil record”
D
Living system
in the past
A
Kalahari hunter
& gatherer
Behaviour
(ethnographic
observation)
D
Prehistoric hunter
& gatherer
behaviour
(archaeological
observation)
C
Fossil record
B
Material and
organic debris
of hunters
and gatherers
C
Archaeological
record
(excavation)
Analogue from present to past
How did they hunt?
• African hare: quick but vulnerable
– when the hare is about to dodge, it lays its ears all the
way back
– seeing this hunter veers L or R (50% chance of being
right)
– if hunter guessed wrong, the hare will usually run for
cover and stay there without moving
– primates highly developed colour vision will see
through the camouflage
How did they hunt?...persistence hunting
• Insight into animal behaviour: e.g. antelopes and gazelles move
in an arc when trying to escape
• key = persistence, keep it in constant motion until exhaustion
– Tarahumara Indians of Mexico: pursued a deer for 2 days. Never loose
track of its spoor
• Supported by H. erectus anatomy:
– Barrel shaped rib cages:  high levels of sustained activity. Ventilation of
the lungs = enhanced by the ability to raise the upper part of the rib cage
(enlarging the thorax) when taking deep breaths
– Waist allows upper body to twist at the abdomen and arms to swing
freely –stabilises upper body in B. running
– Human leg muscles capable of producing large forces
How did they hunt?... stalking, driving & ambush
• Chimps do it
• Torralba and Ambrona (Spain, 400kya, Acheulean) H. erectus
hunters driving elephants, horses, deer & rhinos into marshy
bogs, killing them & butchering them
• Reanalysis (Klein & Shipman 1980’s) hominins (H. erectus/
heidelbergensis) used some of the carcasses (cut marks), no
conclusive evidence of actual hunting
– ? scavenging the remains of animals that had died naturally
or killed by carnivores
• 1st confirmed driving/ambush  La
Cotte de St. Brelade (Jersey):
mammoth and rhino drives (240kya125,kya). H. heidelbergensis
Cannibalism
• Zoukoudian: human skulls – faceless & had been opened at the
base
– ? cannibalism - eating the brains of the
dead
– a lack of ‘humanity’ or culture (spiritual
notion that cannibalism could increase
their powers)
– cannibalism in recent times: the act is
nearly always carried out as a ritual not
for food
– Distinction between dietary and ritual
cannibalism = extremely important: its
very rare for people to eat other people
merely for food
Cannibalism
but,…
• Lewis Binford: hominin remains are
found in deposits containing many
other bone fragments, including
numerous predators (e.g. Chinese
hyena)
• The removal of the faces/ destruction
of the skull base = what happens
when gnawing carnivores chew out
the face of their prey
• Fossils disappeared in WWII
Cannibalism
• Middle awash in Ethiopia:– (Tim
White)
– curious marks on the skull of H.
erectus: forehead of the individual and
around and inside the left eye socket
– ? scalping & removing tissue from the
face
• Why would another hominid have
done such a thing?
• Whether it remains cannibalism,
head hunting, or some other
behaviour remains a mystery at
present
• Indicates developed culture
Conclusion
• Nomadic - following migrating herds = problems: transporting
food and water
– No direct evidence
– ? bags made of animal hides; containers
made of wood, leaves, clay?
– Material for toolmaking - probably
transported, tools often made at the
butchery site
– Cooler climates may have stimulated the
control/use of fire and the construction of
clothing (animal pelts, e.g. Terra Amata:
bedding)
• All these behaviours can be related to meat eating
• Put an even higher premium on continued and better access to
meat