Post Lab Chapter 13

Post Lab & Exercises Chapter 13 1. What is the purpose of a diastema? To accommodate the enlarged lower canines. 2. Why did the early hominins have thick enamel? What kind of foods might they have been eating? Thick enamel is stronger and lasts longer. Hominins had thick enamel because they ate foods like nuts, roots, and seeds. 3. Examine the following illustration. Does this foot belong to a human or an ape? Name three characteristics that helped you decide. Long toes, curvature in the digits, and divergent hallux leads me to believe that this foor belongs to an Ape. 4. Examine the following illustration. Does this pelvis belong to a human or an ape? Name two features that helped you decide. This pelvis belongs to a human because the pelvis is short and broad while the ilia curves anteriorly forming a sort of bowl like shape. 5. How did the adoption of bipedalism affect estrus in females? No genital swelling. 6. What are some disadvantages to bipedalism?

Issues with pain in feet because of the heavy body weight being on two feet and more difficult childbirth. 7. Why do you think bipedalism might be an advantage for the early hominins? In other words, how might being bipedal have helped them survive? They could move easier with two feet because their hands could be used freely instead of having to walk on them. 8. Examine the following figure. Is this the palate of a human or an ape? How can you tell? This palate is an Ape’s palate because of the parallel rows of teeth and the large sized canines. 9. Fill in the following chart with information comparing apes to humans. Trait Ape Human Sectorial premolar (yes/no) Yes No Diastema for canine (yes/no) Yes No C/P3 hone (yes/no) Yes No Molar enamel (yes/no) Thin Thick Tooth rows (parallel/parabolic) Parallel Parabolic Brain size 400cc 1350cc Foramen magnum location Posterior Anterior Vertebral column Straight 2 Curves Pelvic girdle Tall/thin/flat on back Short/broad/curved Femur/knee Straight femur/Verus knee Angled femur/Valgus knee Foot, arches One: transverse Two: transverse/longitudinal Foot, hallux Divergent/grasping Non-divergent Foot, toe length Long/curved Short/straight Gluteal muscles Act as extensors/propulsive Act as stabilizers Calf muscles Smaller=less propulsion Large/propulsive 10. Based on the comparison you made in lab (Exercise 6), do you think the australopithecines had a locomotor pattern more like chimpanzees or like humans? Explain. 11. Examine the following figure. Describe the similarities and differences between the australopithecine morphology of the pelvic girdle, femur, and knee when compared to the morphology of the human and chimpanzee.

I believe the Taung child was roughly 4 years old and that she or he aged like something in between an ape and human. 15. Review the information that you recorded in class for Exercise 9 and answer the following questions. a. Name at least two features in the australopithecines that are still ape-like. Brain size (400cs) and projecting face. b. Name three features of the skull (not teeth) used to distinguish the robusts from the graciles. Dished face, sagittal crest, and flaring zygomatics. c. Name three dental features that distinguish the robusts from the graciles. Small incisors, megadontia, and possible molarized premolars. d. Does brain size increase much in the australopithecines through time? No. e. What were the robusts using those huge teeth for anyway? For eating hard foods such as roots, seeds, nuts, etc.

EXERCISE 9 Casts or photos of several australopithecine species are available in your laboratory. After examining them carefully, fill in the following chart. Traits afarensis africanus aethiopicu s robustus boisei chimp Dates ~2.5 mya 2 to 1.5 mya 2.5 to 1 mya Sites East Africa, Lake Turkana S. Africa East Africa (Olduva i Gorge) Size of incisors (small/large) Large Small Small Size of cheek teeth (small/large) Large Large Large Size of canine (small/large) Small Small Small Diastema (yes/no) No No No Molarized premolars (yes/no) Yes Yes Yes Projecting face (yes/no) Yes No No Compound temporonuchal crest (yes/no) Yes No No Nuchal crest (yes/no) Yes Yes Yes Sagittal crest (yes/no) Yes Yes Yes Flaring zygomatics (yes/no) Yes Yes Yes Dished face (yes/no) Yes Yes Yes