Transcript Lab 2: Hominid Anatomy

Lab 2:
Hominid Anatomy
Key features to know
Lab Materials
Skeletal Changes In Human Evolution
The earliest humans evolved in a parallel track with other primates. To understand
the anatomical differences from an paleoanthropological perspective, you have to
look at the fossils. You also have to understand some basic skeletal anatomy. This
discussion section should help you recognize and understand major features and
changes as apparent from the skulls. In section, you can handle skull casts of some
of the non-human primates and some of the fossil hominids. You'll also have a
simple classification exercise based on the skeletal features.
The list of terms below is certainly not a complete list of all the anatomical
comparisons, but you should know what they mean and where possible, you
should look at each specimen so you have a better understanding.
In class, you’ll look at parts 1-2 of the recent video series Ape Man which clearly
shows the relationships and development of human evolution and anatomy. A book
of the same title is also available.
The terms listed below will all be explained in the class demonstrations and handson activities. Try to note what each term means and how the characteristics
changed as our species evolved.
Terms to know
Try to understand the relationship between these elements
in terms of the trends for evolutionary change.
Locomotion
• Bipedal
locomotion
Upright posture
Stride
Great toe
The Hand
• Brachiation
Opposable thumb
Precision Grip
Power Grip
The Skull
• For an excellent web presentation and
tutorial on the human (H.s.s.) skull, visit the
Skull Module from the Department of
Anthropology at CSU-Chico
(http://www.csuchico.edu/anth/Module/skull.
html.
• Crests (saggital, occipital)
Foreman magnum
Dental Arcade/Arch
Y-5 Cusp pattern
Supraorbital torus
Zygomatic arch
Mandible
Vaulted forehead
Cranial capacity
Binocular vision
Diastema
Erect posture
Shape of spinal column
Rare, but possible,
true or pseudo
human tails
Skeletal implications of bipedalism
Location of foramen magnum
Bipedal Locomotion
Laetoli
Footprints
Chimp and
human foot
Femurs of upright walkers and ape
Leg of ape
Quadrupedal animals like
apes, have femurs in which
the ball joint, the part that
joins the pelvis, sits
directly over the inside of
the knee. The angle
subtended by the femur at
the knee in quadrupedal
walkers is less than that of
bipedal walkers.
Leg of Australopithecus afarensis
This diagram shows the femur
with the same shape and
structure as that of modern
humans, but it is a little shorter. It
subtends the same angle at the
knee as that of a modern human
and the inner bump of the knee
joint is larger than the outer one.
This shows that this hominin was
also a bipedal walker.
Leg of modern human
This modern Homo sapiens bone
shows the structure of the femur
of an upright walker or bipedal
animal. The ball joint, the part that
joins the pelvis, sits directly over
the outside of the knee. The angle
subtended by the femur at the
knee in bipedal walkers is greater
than that of quadrupedal walkers.
This results in the inner bump of
the knee joint being longer than
the outer bump.
Skeletal implications of bipedalism
Pelvis, femur feet
Skeletal implications of bipedalism
Chimp vs. A. afarensis
Knock-kneed walk
Human Bipedalism—Balanced on the
Edge of Disaster
Eadweard Muybridge (1830-1904) did
early studies of human locomotion
Prognathism
“Muzzle” angles (prognathism) of ape and modern human
Pongid Prognathism.
(Line of greatest muscle force is shown in red.)
Understanding Physical Anthropology and Archaeology, 8th ed., p. 245
Satittal crests and temporal muscle orientations.
Hominid compared to pongid.
(Line of greatest muscle force is shown in red.)
Understanding Physical Anthropology and Archaeology, 8th ed., p. 245
Human and Ape Brains
Humankind Emerging, 7th ed., p. 389
The brains develop in . . .
• size
• complexity
• the ratio of brain weight to overall body
weight
Cranial Capacity
Understanding Physical Anthropology and Archaeology, 8th ed., p. 234
Cranial Capacity & Vaulted Forehead
Australopithecus afarensis
Homo (sapiens?)
neandthalensis
Homo erectus
Homo sapiens
sapiens
Teeth / Dental Arcade
Monkey & Ape Canines
Apes (and monkeys)
still possess conical,
dagger-like canines
which project well
beyond the surface of
the opposite teeth.
The gap is a diastema.
Teeth of a male patas monkey.
Understanding Physical Anthropology and Archaeology, 8th ed., p. 231
Molar
Cusp
Patterns
plus-4
Y-5
Y-5
Example of early hominid
fossil Y-5 cusp pattern molars
Dental formulae
Understanding Physical Anthropology and Archaeology, 8th ed., p. 125
Changes in dental arcade
Proconsul heseloni
19 - 17 mya
Homo erectus
500,000 - 300,000 y
Modern
Chimp
Australopithecus
africanus,2.8 - 2.3 mya
Modern homo sapiens
100,000 ya to now
The Overall Pattern Is Toward
Small Jaws and Teeth
Crests and other muscle attachments
Crests and other muscle attachments
zygomatic arch
Mandible and chewing
Muscle attachments
Some Important Skull Features
Modern human cranium.
Understanding Physical Anthropology and Archaeology, 8th ed., p. 510
For a nearly complete look at skulls, click on the image above for the
Australian National Museum’s web site.
Adding to the confusion:
Sexual Dimporhism
How much do we see in the fossil record?
Be sure to look at Becoming
Human, the Institute for Human
Origins broadband documentary
and web site.