Lab 2: Hominid Anatomy

Key features to knowModified from www.iupui.edu

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 hands-on activities. Try to note what each term means and how the characteristics changed as our species evolved.

Terms to know

Locomotion• Bipedal

locomotionUpright postureStrideGreat toe

The Hand• Brachiation

Opposable thumbPrecision GripPower 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 magnumDental Arcade/Arch

Y-5 Cusp pattern Supraorbital torus

Zygomatic archMandibleVaulted foreheadCranial capacityBinocular visionDiastema

Try to understand the relationship between these elements in terms of the trends for evolutionary change.

Erect posture

Shape of spinal column

Skeletal implications of bipedalism

Location of foramen magnum

Bipedal Locomotion

Laetoli Footprints

Chimp and human foot

Femurs of upright walkers and ape

Leg of apeQuadrupedal 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 afarensisThis 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 humanThis 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

Knock-kneed walk

Chimp vs. A. afarensis

Understanding Physical Anthropology and Archaeology, 8th ed., p. 245

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.)

Humankind Emerging, 7th ed., p. 389

Human and Ape Brains

The brains develop in . . .

• size

• complexity

• the ratio of brain weight to overall body weight

Understanding Physical Anthropology and Archaeology, 8th ed., p. 234

Cranial Capacity

Cranial Capacity & Vaulted Forehead

Homo erectusAustralopithecus afarensis

Homo (sapiens?) neandthalensis Homo sapiens

sapiens

Teeth / Dental Arcade

Apes (and monkeys) still possess conical, dagger-like canines which project well beyond the surface of the opposite teeth.

The gap is a diastema.

Monkey & Ape Canines

Teeth of a male patas monkey.

Understanding Physical Anthropology and Archaeology, 8th ed., p. 231

plus-4

Y-5

Y-5

Molar Cusp

Patterns

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

 

Modern Chimp

Modern homo sapiens 100,000 ya to now

Homo erectus 500,000 - 300,000 y

Australopithecus africanus,2.8 - 2.3 mya

Proconsul heseloni 19 - 17 mya

Crests and other muscle attachments

Crests and other muscle attachments

zygomatic arch

Mandible and chewing

Muscle attachments

Some Important Skull Features

Understanding Physical Anthropology and Archaeology, 8th ed., p. 510

Modern human cranium.

For a nearly complete look at skulls, click on the image above for the Australian National Museum’s web site.

 

Be sure to look at Becoming Human, the Institute for Human

Origins broadband documentary and web site.