Lab 2 Hominid Anatomy Key features to know

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, 8 th 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, 8 th ed. , p. 245

Human and Ape Brains Humankind Emerging, 7 th 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, 8 th ed. , p. 234

Cranial Capacity & Vaulted Forehead Australopithecus afarensis Homo (sapiens? ) neandthalensis Homo erectus Homo 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, 8 th ed. , p. 231

Molar Cusp Patterns plus-4 Y-5

Example of early hominid fossil Y-5 cusp pattern molars

Dental formulae Understanding Physical Anthropology and Archaeology, 8 th ed. , p. 125

Changes in dental arcade Proconsul heseloni 19 - 17 mya Modern Chimp Australopithecus africanus, 2. 8 - 2. 3 mya Homo erectus 500, 000 - 300, 000 y 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, 8 th 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.