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Human Evolution > Locomotion > Flashcards

Locomotion Flashcards

1
Q

Give 7 reasons locomotion and postures are important

A 
resting
traveling
infant carrying
escaping from predators
foraging
social communication
object manipulation/
carrying
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2
Q

Define locomotion and posture

A

locomotion
move from one place to another, displacement
postures

positions/attitudes,
no significant displacement

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3
Q

What is the positional repertiore

A

all of the locomotor and postural activities of an individual/ species.

one activity may be the most important

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4
Q

What is the substrate

A

: the surface on which an animal moves, it could be terrestrial (ground) or arboreal (lianas, branches)

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5
Q

What is gait

A

repeated cycles of limb movement during steady locomotion.

Different parts of the body in contact with the ground between and within cycles

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6
Q

What does frequency refer to when describing locomotion

A

Frequence: occasional vs habitual behaviours.

eg human: obligate terrestrial bipedalism vs chimp: occasional terrestrial bipedal walking

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7
Q

What is orthnograde and pronograde

A

Orthograde: upright. • Pronograde: longitudinal axis of the body parallel to the ground.

Orthograde can also be if climbing trees

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8
Q

Give the quotation from Stern and Oxnard (1973) showing the unique locomotor diversity of primates

A

“Primates stand, sit, lie, walk, run, hop, leap,
climb, hang, swing, swim, and engage in other
activities too numerous to mention. They may
do these things often or rarely, quickly or
slowly, with agility or clumsiness, on the
ground or in the trees (or, with swimming, in
the water), on thick branches or thin ones, on
vertical, oblique or horizontal supports, with
all appendages or only some.”

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9
Q

Why is there such a diversity of locomotor abilities in primates (2, elaborate on each)

A

differences in body size, i.e., small primates tend to be more arboreal,
and large primates are more terrestrial

habitats, primates in savannah will be more terrestrial while in the
forest there are multiple levels of the canopy that could be exploited by arboreal primates

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10
Q

What are the 6 main locomotor behaviours of primates according to Fleagle 2013

A 
arboreal quadruped
terestrial quadruped
knuckle-walking quadruped
leaping
suspensory climbing
bipedalism
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11
Q

Describe knuckle walking

A

fingers in a partially flexed posture

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12
Q

Describe suspension locomotion

A

limbs loaded in tension, spread their weight among small supports includes orthograde suspension
(brachiation, using arm swinging

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13
Q

Describe leaping

A

leaping (saltation)
cover distances in free flight,
move between discontinuous supports

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14
Q

Describe bipedalism

A

bipedalism
progress on a continuous
substrate, frees the hands

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15
Q

Describe terrestrial/arboreal quadrupedalism

A

progression on small supports using all four limbs

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16
Q

What is vertical climbing

A

• Vertical climbing: moving up vertical substrates.

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17
Q

How many modes and sub-modes of primate locomotion/postures are there

A

Hunt et al. (1996): up to 32 positional modes, including 52 postural sub-modes
and 74 locomotor sub-modes!

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18
Q

How does the inner ear differ depending on locomotor activity (generally)

A

Inner ear: size and orientation of the semicircular canals differ, large anterior
canal in humans

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19
Q

How does the vertebral column differ between human and non human great apes

A

non humans great apes

  • « short-backed »
  • reduced lumbar number (3-4)
  • immobile lower spine
  • straight spine

humans

  • « long-backed »
  • greater overall lenght (5 lumbar)
  • flexible spine
  • lumbar and cervical lordosis
  • thoracic kyphosis
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20
Q

Describe the bipedal pelvis of a human

A

shortened ilium (body and blades, lower centre of mass), iliac blades
more laterally placed (bowl shape), large sacrum (no entrapment of the lumbar
vertebrae) in humans

 Chimp entrapment of sacrum limits its flexibility

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21
Q

Describe the bipedal femur of a human

A 
long neck (increase the mechanical advantage), bicondylar angle (feet
below the center of gravity) and linear aspera (muscle attachments) in humans
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22
Q

Describe the bipedal adaptations of a human tibia

A

: articular facets longer, larger, more concave, medial>lateral facets (weight transfer to the feet) in humans.

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23
Q

Describe phalanges of other primates

A

• Hands: curved hand bones in arboreal primates.

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24
Q

What are the 2 key types of bone tissue

A

compact bone:
cortical
spongious bone:
trabecular

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25
Q

What is Wolff’s Law

what parts of the body have used this to examine bipedalism

A

Wolff’s law: bone tissues adapt to the loads

Bone form reflects mechanical loading history during life. • Bone remodeling: mechano-transduction (mechanical signals converted to
biochemical signals)

cortical thickness in the tibial plateau
(Mazurier et al., 2010)
trabecular bone in the humeral head
(Ryan and Shaw, 2012)

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26
Q

what are the 4 possibilities of positional behaviour before human bipedalism

A

arboreal climbing ancestor? knuckle-walker?

terrestrial quadruped ancestor? arboreal quadruped ancestor?

27
Q

What is the evidence of bipedalism in Sahelanthropus tchadensis
(7.2-6.8 Ma)

what may contradict this

A

cranium reconstruction with a foramen magnum positioned anteriorly
(Zollikofer et al., 2005)

femur showing the linear aspera
(Guy et al., 2020)

ulna is curved

28
Q

Why may orrorin have been bipedal

what contradicts this

A

femur showing the linear
aspera and thick cortical bone
in the femoral neck
(Galik et al., 2004)

arboreal activities in the upper limbs - phalanges and humerus

29
Q

evidence for bipedalism in kadabba

give dates

A

Ardipithecus kadabba
(6.4-5.4 Ma)

human-like foot
(Haile-Selassie et al., 2004)

30
Q

evidence for bipedalism in ramidus

give age

what may contradict this

A

Ardipithecus ramidus
(4.6-4.3 Ma)

short ilium mediolaterally
expanded
(Lovejoy et al., 2009)
cranium reconstruction with a
foramen magnum positioned
anteriorely
(Suwa et al., 2009)

arboreal activities in the upper limbs - hands and feet

31
Q

what is the trend in early hominin locomotor activity

what is the most likely locomotion pre-bipedalism

A

evidence of bipedalism in the cranium and lower limbs and of arboreal activities in the upper limbs.

Terrestrial bipedality combined with climbing capacities. (Bipedalism did not emerge from knuckle-walking.)

32
Q

What is Oldest evidence of habitual bipedalism in Australopithecus.

A

Australopithecus anamensis at Lake Turkana (Kenya) dated to 4.2-3.9 Ma
(Leakey et al., 1995)

KNM-KP 29258.

medial>lateral,
concave facets

33
Q

What evidence is there of bipedalism in afarensis

A

Australopithecus afarensis footprints at Laetoli (Tanzania) dated to 3.7-3.5 Ma (Leakey
and Hay, 1979). • No evidence of forelimb support, human-like gait (heel-strike and toe-off
during stance phase of walking).

Lucy:
pelvis- wide sacrum, short iliac blades

femoral neck
long, thicker cortical bone inferiorly
high bicondylar angle

34
Q

How is Lucy a locomotor mosaic

A

biped:
pelvis- wide sacrum, short iliac blades

femoral neck -long, thicker cortical bone inferiorly
high bicondylar angle

arboreal:
hand - curved and long phalanges
femur - relatively short
distal humerus - well-developed lateral trochlear crest
scapula - cranially oriented

latter 2 suggest above branch climbing

35
Q

Give the mosaic features of the locomotor activity of africanus

A 
biped:
pelvis - wide and short iliac blades laterally flaring
femur - long neck
high bicondylar angle 
lumbar vertebrae - lordosis
6/5

arboreal:
inner ear - ape-like semicircular canals
hand - curved phalanges

36
Q

What are the arboreal/ bipedal features of little foot

A

StW 573 - Australopithecus africanus (3.7-2.2 Ma)

proportions distinct
from humans and apes
long limbs

37
Q

What suggests africanus had a variability in positional repertoire

A

variability in the inner ear morphology
(Beaudet et al., 2019)

variability in the sacrum
(Fornai et al., 2020)

variability in the vertebral morphology
(Beaudet et al., 2020) - (atlas – is very different, one similar to lucy but one more derived etc)

38
Q

Describe the alleged locomotion of sediba

A

Australopithecus sediba (2.0 Ma): supports locomotor and postural diversity within Australopithecus

mosaic:

biped:
pelvis - very human-like

arboreal;
scapula - cranially oriented
humerus - marked crests
foot - more primitive
hand - curved phalanges
39
Q

What is The problematic assignment of postcranial remains to Paranthropus?

A

stratigraphic association with Homo, → postcranial material not systemically found in association with
craniodental remains

40
Q

What do we know about Paranthropine postcrania and thus the locomotor activity

A

The fragmentary material from Kenya and Tanzania.

biped:
human-like features:
fine grip precision, femoral lines

arboreal hominoid-like features:
scapula, proximal radius

specific features
straight and robust radius, thick
cortical bone in the humerus

41
Q

What are the locomotor traits of Homo skeletons

A

Early Homo and the emergence of obligate bipedalism. • Obligate bipedalism and possible endurance running in Homo ergaster. • Primitive (arboreal?) traits in Homo habilis

42
Q

How are H sapiens adapted to long distance running

A

Skeletal strength
Stabilisation
Thermoregulation

43
Q

How is the H sapiens adapted to increase skeletal strength for running (2)

A

1) expand joint surfaces in lower body disproportionally cf. upper body (Homo has larger articular surfaces cf. Au. eg in femoral head and knee)
2) shorter femoral neck cf Pan and Au - reduces bending moments in femoral neck

44
Q

How do Homo species improve stability for endurance running to counter the following problems:

1) trunk and neck of human runners are more forwardly inclined during running than walking
2) during the aerial phase of running, leg acceleration generates even larger torques that cannot be counter-acted by ground forces (as in walking).
3) head stablisation

A

1) enhance trunk stabilization, including expanded areas on the sacrum and the posterior iliac spine for the attachment of the large erector spinae muscles, and a greatly enlarged m. gluteus maximus

2) offset by the opposing torques produced by counter-rotation of thorax and arms (but not the head)
- greater degree of isolated rotation of the trunk relative to the hips compared to apes
- greater structural independence of the pectoral girdle and head
- wide shoulders + reduced forearms allows energy saving in arm swinging for counter-balancing

3) radius of posterior semicircular canal is significantly larger in Homo than in Pan or Australopithecus, presumably increasing the sensitivity of sensory perception to head pitching in the sagittal plane, which is potentially much greater during running than walking

nuchal ligament (convergent evolution with other running mammals eg horses and hares)

45
Q

How does Homo achieve greater independence of head from pectoral girdle

A

chimps have extensive muscle connections between shrugged shoulders and head but humans have only trapezius

cranially orientated glenoid fossa (fine for walking) would impede counter-rotations of pelvis and arms

(this decoupling of the head and pectoral girdle may also be advantageous for throwing)

46
Q

How has Homo sapiens improved thermoregulation for endurance running

A
  • Elaboration and multiplication of eccrine sweat glands for evapo-transpiration, and reduced body hair
  • narrow, elongated body form
  • enhanced cranial venous drainage (venous blood that has been cooled by sweating in the face and scalp to cool, via countercurrent heat exchange in the cavernous sinus, hot arterial blood in the internal carotid artery before it reaches the brain)
47
Q

Why do we think Orrorin was bipedal

why not

A

Femur:
• A large femoral head that is anteriorly twisted
• Elongated femoral neck
• A femoral neck that is compressed antero-posteriorly
• Inferiorly thickened femoral neck cortex (seen in humans - superior thickening seen in apes)
• An obturator externus groove
• A medially projecting lesser trochanter
• A well-developed gluteal tuberosity

Phalanges show similar curvature to afarensis with deep lateral fossae for insertion of flexor digitorum superficialis – strong hand flexing musculature

48
Q

Give a feature of Sahelanthropus’ forearm

A

waisted trochlear notch - arboreality would require fully developed notch BUT this trait could not be selected for and independent of walking

Guy et al 2020

49
Q

Describe the hands and wrists of ramidus

what about forearm

A

Primitive hands – short, grasping
thumbs and elongated fingers
• Wrist: arboreal palmigrady

Radius:tibia – similar length – consistent with above branch quadruped

50
Q

Give the key features of ramidus’ pelvis (3)

What must be remembered about this evidence

A

1) Ilium shortened in height cf apes - ilium shifted to become more anterior and basin-like, away from the vertical ilium in Pan. This shift allowed the gluteal muscles to be positioned in a more advantageous position for centering ramidus’ centre of mass while walking
2) Has an incipient anterior inferior iliac spine – prominent in humans but not present in apes
3) Ape like ischium

Pelvis is crushed so limits reliability

51
Q

Describe sediba’s back

A

has a lumbar lordosis and vertebral pyramidal configuration consistent with bipeds

long costal processes for psoas major attachment imply increased Tm for this muscle, aiding trunk stablisation in upright walking and vertical climbing

adapted for bipedalism and arboreality

52
Q

Describe sediba’s shoulder

A

sternoclavicular joint suggests oblique orientation of clavicle and high scapula

cranially oriented glenoid fossa

retention of climbimg abilities likely signals full reorganisation did not occur until total commitment to terrestriality, which was when upper limbs became more prehensile and manipulative

53
Q

Give key hypotheses for the evolution of hominin bipedalism

A

Multiple factors

Savannah-based theory

Traveling efficiency hypothesis

Postural feeding hypothesis

Provisioning model

Thermoregulatory model

Carrying models

Wading models

54
Q

Who is a key proponent of the provisioning hypothesis of bipedality

What does it suggest

Support?

Problems?

A

Lovejoy -> male provisioning

slow LHS required males to go out and find food for females which requires hands for carrying etc

based on reduced canine dimorphism in Sahelanthropus and ramidus and ovulatory crypsis

but kadabba has large canine? and honing complex?
afarensis were sexually dimorphic and lived in large groups unlike extant monogamous primates eg gibbons

55
Q

What is the Postural feeding hypothesis

A

Primates were only bipedal when reaching for branches/ high up food

56
Q

Give evidence for the Postural feeding hypothesis

A

Australopithecus afarensis has similar shoulder to chimp and the lower limb/ hip is inefficient at movement, suggesting it may have been important postural originally

orangutans walk bipedally through branches using forelimbs to hold higher branches (75% of observations by Thorpe)

explains instability of afarensis’ ankle joint

57
Q

What is the Traveling efficiency hypothesis

Is there any evidence?

A

the mixture of savanna and scattered forests increased terrestrial travel by proto-humans between clusters of trees, and bipedalism offered greater efficiency for long-distance travel between these clusters than quadrupedalism

metabolic cost of bipedal and quadrupedal locomotion are similar in chimpanzees (Pontzer, 2014)

58
Q

What are key features of the savannah hypothesis

A

evolution of an orthograde posture would have been very helpful on a savanna as it would allow the ability to look over tall grasses in order to watch out for predators, or terrestrially hunt and sneak up on prey

thermoregulation

59
Q

What is the wading model of the evolution of human evolution

evidence?

A

apes selected for bipedalism due to need to wade for foods containing essential fatty acids

captive bonobos found them to exhibit <2% bipedality on the ground or in trees but over 90% when wading in water to collect food

this explanation of A. afarensis locomotor morphology
is more parsimonious than others which have plainly failed to produce a consensus

Sahelanthropus may have lived near the Mega Lake Chad

not taken seriously (Meier, 2003)
eg Orrorin did not have an aquatic paleohabitat

60
Q

What is the Multiple factors model of bipedalism

A

Because biological evolution is not a simple causation; there may be multiple answers to the evolution of bipedalism.
The postural feeding hypothesis (reaching for food/balancing) provides an explanation for the partial bipedalism of the earliest hominins.

The savannah-based theory describes how the largely bipedal hominins that started to settle on the ground became increasingly bipedal.

The provisioning model (food-gathering/monogamy) explains questions arising after the postural feeding hypothesis and before the savannah theory in an evolutionary timeline.

Endurance running explains shift to efficient bipedalism in Homo

61
Q

Describe the angular relationship between foramen magnum (FM) and orbital (OP) planes in S tchadensis

A

quad and bipedal primates have face facing forward so have small angle compared to humans which have an angle between FM and face of 103 degrees (almost right angle) – Sahelanthropus has angle of 95 degrees also close to right angle – evidence of bidepalism

62
Q

Does an anterior FM necessarily suggest bipedal walking

A

This does not necessarily mean that it walked upright on the ground, but at least we know their heads were more closely above the body, indicating a habitually upright posture.

63
Q

What is the importance of the bicondylar angle

Which hominins have this

A

phenotypically plastic trait, meaning that it only appears through behaviour. Humans that were not able to walk as children never develop this trait.
Therefore, if we see it we know that the individual walked bipedally.

Orrorin
afarensis
africanus 
robustus 
boisei
64
Q

What are the key features of a modern human pelvis

Which of these does ramidus have

A

1) A wide and short sacrum
2) Laterally oriented iliac crests that turn the gluteus minimus and gluteus medius into abductors
3) The ilium is shorter and broader in humans than in apes
4) Anterior inferior iliac spine

All of the above BUT has long (ape-like) ischium for adductor and hamstring attachment needed in arboreal climbing

Human Evolution (16 decks)

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