Outline:

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Lecture 3 Bipedalism

• Outline
• Bipedalism
• The hands were freed upfor what?
• The Savannah hypothesis
• The Throwing Theory

Readings Chapts 3 and 8 in Corballis Lea
(2000) Chapt 4 and 5 in Corballis (2002)
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The Hominins IV
http//www.mnh.si.edu/anthro/humanorigins/ha/a_tre
e.html
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The Hominins V
Stringer, C. (2003). Out of Ethiopia. Nature,
423, 692-694.
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The Hominins VI
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From the American Museum of Natural History
Website (See notes pages)
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The Hominins VII
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The Hominins VIII
Homo floresiensis (Nature, 2004)
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From Falk et al. (2005). The Brain of LB1, Homo
floresiensis. Science, 308(5719), 242-5.
Morphometric , allometric and shape data
indicate that LB1 is not a microcephalic or
pygmy. LB1s brain size versus body size scales
like an australopithecine, but its endocast shape
resembles that of Homo erectus. LB1 has derived
frontal and temporal lobes and a lunate sulcus in
a derived position, which are consistent with
capabilities for higher cognitive processing
(from the Abstract).
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From Lieberman DE, Krovitz GE, and McBratney-Owen
B (2004) Testing hypotheses about tinkering in
the fossil record the case of the human skull.
Journal of Experimental Zoology (Mol. Dev. Evol.)
302B 284-301.
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Bipedalism I
When did it evolve? And how would we know?

• Blumenbach, J. (1795) Of the Difference of Man
  from Other Animals
• Humans
• abandoned infants (wolf children) develop
  upright locomotion
• crawl on hands and knees, not on all four feet
• our ankle bones develop before the wrist (in
  quadrapeds opposite or simultaneous)
• have long strong legs, short trunk, short
  (weakish) arms
• have a wide pelvis, cupping our viscera
• Jo-Lo butts (swollen buttocks)

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• From Extinct Humans (2001) by Tattersall and
  Schwartz. Westview Press
• Aristotle thought that human also differ from
  birds, and from all mammals for that matter, in
  the direction in which their knee joint flexes.
  He mistakenly believed that this joint bends
  backwards in birds and mammals and forwards in
  humans. On the basis of this seemingly profound
  difference, Aristotle singled out humans from
  other animals and proclaimed that their
  bipedalism reflected divinity both in their
  nature and in their essence. Aristotles
  anatomical misconception stayed on the books
  until the fifteenth century, when Leonardo da
  Vinci finally pointed out that the joint that
  Aristotle had mistaken for the knee in birds and
  non-human animals was really their ankle joint.
  Tattersall and Scwartz (2001) pg. 16.
• Peter McGeorge comments Good scientists should
  avoid knee-jerk reactions.

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Bipedalism II
hands and feetsimilar basic design in most
vertebrates
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Bipedalism III

• Primates are vertical creatures
• Most animals climb using claws
• - primates have prehensile hands (and feet)

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Bipedalism IV
Does digit orientation in foot bones of other
primates imply good for swinging mann?
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Bipedalism V
http//sellers.sbc.man.ac.uk/wis/lectures/primate
-adaptation/07OWMsAndHominoids.pdf
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Bipedalism VI
Chimpanzee versus Homo sapien gait

• Striding gait of bipedalism---has swing phase and
  stance phase
• Three key features (Lewin, 2005)
• Chimps cant produce a straight leg in the stance
  phase. More muscles required
• During swing phase centre of gravity has to shift
  towards supporting leg in humans angled upper
  legs
• Design of human foot makes it a
  propulsion-contributing lever

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Bipedalism VII
Knee jointscarrying angle---in bipeds, upper
legs come together at knee
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Bipedalism VIII
Other changes
The feet of bipeds.early bipeds..weight is
medial and pushes through middle
toes..laterouter, then middle to ball of foot
and big toe Hence why physical anthropologists
LOVE footprints
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Bipedalism IX
note how A. afarensis hand looks like Homo sapien
hand
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Bipedalism X
chimp A. anamensis Homo sapiens
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Bipedalism XII
Richmond (2001). Origins of human bipedalism the
knuckle-walking hypothesis revisited. Yearbook of
Physical Anthropology, 44, 70-105.
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Bipedalism XIII

• The Savannah theory (Dart, 1925? or The East
  Side Story)
• bipedalism as a consequence of moving out of
  arboreal environments into Savannahscarce
  resources, mammalian competition, etc.
• upright posture better for predator and prey
  detection
• upright posture reduces exposure to the suns
  rays (and heat from the ground)
• freeing up hands for collecting and carrying of
  food ( babies!), stones for making tools,
  gesturing to conspecifics.
• long distance, nomadic travel?
• and when? A. afarensis has many joint
  adaptations of tree climbers (but seemed to be
  bipedal 3.5 to 3 million years ago?)

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Bipedalism XIV

• The Savannah theory .. problems
• Fossilised plants found by many sites where
  Australoptihicus are found are not vegetation
  from savannah.
• Ardipithicus from either side of an area that
  was a large lake in Ethiopia
• A. anamensis from a region of a river, bordered
  by forrest etc.
• Sahleanthropus from west of the great Rift
  Valley
• Bonobos (who live in arboreal environments) are
  probably more Homo-like than chimps who live in
  more Savannah-like habitats (i.e. tool use)

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Bipedalism XV
Bipedalism has probably been around for 4 million
years plus. It might be one of many necessary
conditions for the emergence of Homo but probably
wasnt sufficient
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from Hedges (2000) Nature, 408.
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Primate Hands and Arms Throwing I
many preadaptations present in many primate
speciessemi-opposable thumbs, clavical
shoulder design, etc. Capuchin monkeys can
allegedly throw stones, bipedal and overarm
(Westergaard et al. 2000)
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Primate Hands and Arms Throwing II
Calvin (1983) A stones throw and its launch
window. J Theor Biol argues for the importance of
ballistic missile use in bipedal hunting timing
constraints on release are severe motor
sequencing also important Reprinted
at http//williamcalvin.com/1980s/1983JTheoretBio
l.htm
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Primate Hands and Arms Throwing III
not very accurate in any species besides ours not
very lateralised in many species besides ours not
very coordinated in many species besides
ours only practised by our species and done for
fun (e.g. Donald, in Corballis Lea
2000) sexually dimorphicsexual selection of good
male hunters? Watson, N. (2001) Current Biology,
March 2001.
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Primate Hands and Arms Throwing IV
What is the hominid growth curve for hammering
nuts? Given how skillful the chimpanzees studied
by Boesch Boesch (1981) seem to be (at least,
at positioning the targets the hammering
sequence may not be as carefully varied), that
curve might have been close to a plateau even in
our common ancestor. This is in contrast to
throwing's growth curve. Chimpanzees mostly
engage in threat throwing, trying to intimidate
leopards, snakes, and fellow chimps it seems to
be an adjunct to flailing about with a branch,
rocks being secondarily used. The great growth
potential comes with converting the threat throw
into a predatory throw (see Plooij, 1978, for one
possible scenario). Action at a distance is an
important invention for hunters, as it reduces
the chances of injury from hooves, horns, and
teeth Calvin W.H. (1993). The unitary
hypothesis A common neural circuitry for novel
manipulations, language, plan-ahead, and
throwing?" In Tools, Language, and Cognition in
Human Evolution, Gibson and Ingold (Eds.)
Cambridge University Press, pp. 230-250.
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Primate Hands and Arms Throwing V
Good news for men who get into fights with their
wives. It's been revealed that women are not as
good as men at throwing things. Researchers at
the US National Institute of Child Health and
Human Development found that men have a
significantly better aim than women when throwing
balls or stones into a bucket either 9ft or 18ft
away. Scientist Greg Westergaard said "We always
thought women were better throwers because they
had to hold a baby with one hand and throw with
the other to ward off predators, but that didn't
turn out to be the case." Be warned though, it's
a known fact that when they get upset, women can
throw anything at us men - and do. Their aim
seems to improve radically with a raise in
temper... The Telegraph Women Cannot Throw Oct
12, 2000.
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Primate Hands and Arms Throwing VI
Ananova  Police chase apple-throwing
monkeys Three monkeys which hurled crab apples at
passing motorists in the US state of North
Carolina are believed to have escaped from a
circus. Police hunting for the animals believe
they escaped while being taken to the state fair
in Richmond. State Trooper Mike Scott says he was
flagged down by a driver near the town of Jarratt
who was the first to tell him the monkey tale -
but he just laughed. He then drove to the scene
of the fruit flinging where two other vehicles
were parked up reports Individual.com. Trooper
Scott said "A man said, 'I know this sounds
crazy but a monkey threw an apple at our
car'. "Lo and behold there were three brown
monkeys in an oak tree throwing crab apples." The
monkeys escaped across the road and into nearby
woods. Story filed 1048 Friday 22nd September
2000 http//www.ananova.com/news/story/sm_65831.ht
ml
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Tools I The Hands were freed upfor what?
Darwin (1871) suggests tool use He has invented
and is able to use various weapons, tools, traps,
etc., with which he defends himself, kills or
catches prey, and otherwise obtains food. He has
made rafts or canoes for fishing or crossing over
to neighbouring fertile islands. He has
discovered the art of making fire, by which hard
and stringy roots can be rendered digestible, and
poisonous roots or herbs innocuous. This
discovery of fire, probably the greatest ever
made by man, excepting language, dates from
before the dawn of history. These several
inventions, by which man in the rudest state has
become so pre-eminent, are the direct results of
the development of his powers of observation,
memory, curiosity, imagination, and reason.
Darwin (1871) The Descent of Man from Chapter
II - On the Manner of Development of Man from
some Lower Form. Http//www.infidels.org/library/h
istorical/charles_darwin/descent_of_man/index.shtm
l
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Next week Lecture 4 Tool Use and Cerebral
Asymmetry Readings Chapts 3 and 11 in Corballis
Lea (2000) Chapt 4 and 5 in Corballis (2002)