chapter 11
DESCRIPTION
Chapter 11. Hominid Origins in Africa. Chapter Outline. The Bipedal Adaptation Early Hominids from Africa (Pre-Australopithecus Finds) Australopithecus/Paranthropus from East Africa Early Homo. Chapter Outline. South African Sites Interpretations: What Does It All Mean? - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/1.jpg)
Chapter 11
Hominid Origins in Africa
![Page 2: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/2.jpg)
Chapter Outline
• The Bipedal Adaptation• Early Hominids from Africa (Pre-
Australopithecus Finds)• Australopithecus/Paranthropus from East
Africa• Early Homo
![Page 3: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/3.jpg)
Chapter Outline• South African Sites• Interpretations: What Does It All Mean?• Seeing the Very Big Picture: Adaptive Patterns
of Early African Hominids
![Page 4: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/4.jpg)
Plio-Pleistocene
• Pertaining to the Pliocene and first half of the Pleistocene, a time range of 5–1 mya.
• For this time period, numerous fossil hominids have been found in Africa.
![Page 5: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/5.jpg)
Morphological
• Pertaining to the form and structure of organisms.
![Page 6: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/6.jpg)
Bipedalism
• Bipedalism as the only form of hominid terrestrial locomotion.
• Since major anatomical changes in the spine, pelvis, and lower limb are required for bipedal locomotion, once hominids adapted this mode of locomotion, other forms of locomotion on the ground became impossible.
![Page 7: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/7.jpg)
Human os coxae
![Page 8: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/8.jpg)
The Human Pelvis
![Page 9: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/9.jpg)
Ossa coxae
• (a) Homo sapiens. (b) Early hominid (Australopithecus) from South Africa. (c) Great ape.
![Page 10: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/10.jpg)
Muscles That Extend the Hip
• The attachment surface of the gluteus maximus in humans (a) is farther in back of the hip joint than in a chimpanzee standing bipedally. (b) In chimpanzees, the hamstrings are farther in back of the knee.
![Page 11: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/11.jpg)
Line of Weight Transmission
• The line over which a significant weight load is carried.
• In a bone structure, the portion of the bone carrying the load will usually be reinforced (i.e., thicker/buttressed).
![Page 12: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/12.jpg)
Major Features of Hominid Bipedalism
• The foramen magnum (shown in red) is repositioned farther underneath the skull, so that the head is more or less balanced on the spine (and thus requires less robust neck muscles to hold the head upright).
![Page 13: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/13.jpg)
Major Features of Hominid Bipedalism• The spine has two
distinctive curves—a backward (thoracic) one and a forward (lumbar) one—that keep the trunk (and weight) centered above the pelvis.
![Page 14: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/14.jpg)
Major Features of Hominid Bipedalism
• The pelvis is shaped more in the form of a basin to support internal organs; moreover, the ossa coxae are shorter and broader, thus stabilizing weight transmission.
![Page 15: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/15.jpg)
Major Features of Hominid Bipedalism
• Lower limbs are elongated, as shown by the proportional lengths of various body segments (e.g., in humans the thigh comprises 20% of body height, while in gorillas it comprises only 11%).
![Page 16: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/16.jpg)
Major Features of Hominid Bipedalism
• The femur is angled inward, keeping the legs more directly under the body; modified knee anatomy also permits full extension of this joint.
![Page 17: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/17.jpg)
Major Features of Hominid Bipedalism
• The big toe is enlarged and brought in line with the other toes; in addition, a distinctive longitudinal arch forms, helping absorb shock and adding propulsive spring.
![Page 18: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/18.jpg)
Question
• Which skeletal modification was NOT necessary for bipedalism?
a) Development of a second (longitudinal) arch on the foot.
b) Repositioning of the foramen magnum.
c) Shortening and broadening of the pelvis.
d) Shortening of the femur.
![Page 19: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/19.jpg)
Answer: d
• Shortening of the femur was not necessary for bipedalism.
![Page 20: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/20.jpg)
Early Hominid Fossil Finds and Localities
![Page 21: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/21.jpg)
Position of the Foramen Magnum
• (a) a human and (b) a chimpanzee.
• Note the more forward position in the human cranium.
![Page 22: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/22.jpg)
Key Very Early Fossil Hominid Discoveries (pre-Australopithecus)
SiteDates
(m.y.a.)Hominids
East Africa
Middle Awash (Ethiopia;
five localities)5.8–5.2 Ardipithecus
Aramis (Ethiopia) 4.4Ardipithecus
ramidus
Central Africa
Tugen Hills ~6.0 Orrorin tugenensis
Toros-Menalla ~7.0Sahelanthropus
tchadenis
![Page 23: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/23.jpg)
Estimated Body Weights and Stature in Plio-Pleistocene Hominids
Body Weight Stature
Male Female Male Female
A. afarensis 99 lb 64 lb 59 in. 41 in.
A. africanus 90 lb 65 lb 54 in. 45 in.
South African“robust”
88 lb 70 lb 52 in. 43 in.
East African “robust”
108 lb 75 lb 54 in. 49 in.
H. habilis 114 lb 70 lb 62 in. 49 in.
![Page 24: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/24.jpg)
Australopithecus
• An early hominid genus, known from the Plio-Pleistocene of Africa, characterized by bipedal locomotion, a relatively small brain, and large back teeth.
![Page 25: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/25.jpg)
Features of Australopithecus
1. They are all clearly bipedal (although not necessarily identical to Homo in this regard).
2. They all have relatively small brains (i.e., at least compared to Homo).
3. They all have large teeth, particularly the back teeth, with thick to very thick enamel on the molars.
![Page 26: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/26.jpg)
Australopithecine
• The colloquial name for members of the genus Australopithecus and Paranthropus.
• The term was first used as a subfamily designation, but it’s now most often used informally.
![Page 27: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/27.jpg)
Lucy
• A partial hominid skeleton, discovered at Hadar in 1974.
• This individual is assigned to Australopithecus afarensis.
![Page 28: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/28.jpg)
Abbreviations Used for FossilHominid Specimens
Abbreviation Explanation
AL Afar locality
LH Laetoli hominid
OH Olduvai hominid
KNM-ER(or simply ER)
Kenya National Museums, East Rudolf
![Page 29: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/29.jpg)
Abbreviations Used for FossilHominid Specimens
Abbreviation Explanation
KNM-WT(or simply WT)
Kenya National Museums,West Turkana
Sts Sterkfontein, main site
Stw Sterkfontein, west extension
SK Swartkrans
![Page 30: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/30.jpg)
Key East African Australopithecine and Early Homo Discoveries
SiteDates
(m.y.a.)Hominids
Olduvai 1.85–1.0 Australopithecines, early Homo
Turkana 1.9–1.3
3.5–1.6
Many australopithecines; several early Homo Paranthropus; also Kenyanthropus 2 nearly complete crania; 3 jaw fragments, isolated teeth; 1 nearly complete skeleton (H. erectus)
![Page 31: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/31.jpg)
Key East African Australopithecine and Early Homo Discoveries
SiteDates
(m.y.a.)Hominids
Bouri 2.5 Australopithecines (A. garhi)
Hadar 3.5–3.0 Many early australopithecines (A. afarensis);
Laetoli 3.6–3.4 Early australopithecines (A. afarensis); well-preserved footprints
![Page 32: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/32.jpg)
Laetoli
• Dated at between 3.5 and 3.7 m.y.a.• Fossilized hominid footprints were found
in an ancient volcanic bed. • Despite agreement that these individuals
were bipedal, some researchers feel they were not bipedal in the same way as modern humans.
![Page 33: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/33.jpg)
Hadar (Afar Triangle)• Dating suggests a range from 3.9 to 2.3 m.y.a.• Recovered:
"Lucy" an Australopithecus afarensis female, was recovered here.
Group of bones representing 13 individuals, including 4 infants, suggest a social unit died at the same time.
Some stone tools may be 2.5 million years old, making them the oldest cultural evidence yet found.
![Page 34: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/34.jpg)
Koobi Fora (East Lake Turkana)
• This site yielded the richest assemblage of Plio-Pleistocene hominids from the African continent.
• Most of the hominids date to 1.8 m.y.a., others date back to 3.3 m.y.a.
• 150 hominid specimens recovered at Koobi Fora represent at least 100 individuals.
![Page 35: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/35.jpg)
West Turkana
• Two important discoveries: Discovery of a nearly complete 1.6
m.y.a. Homo erectus adolescent. Discovery of “the black skull”, a
well-preserved 2.4 million year old skull which caused a major reevaluation of Plio-Pleistocene evolution.
![Page 36: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/36.jpg)
Question
• Which of the following is the site where a 75 foot long trail of hominid footprints was found?
a) Olduvai
b) Laetoli
c) West Lake Turkana
d) Aramis
![Page 37: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/37.jpg)
Answer: b
• Laetoli is the site where a 75 foot long trail of hominid footprints was found.
![Page 38: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/38.jpg)
Question
• The early primitive (4.2-3.0 m.y.a.) hominids from East Africa have been named:
a) Orrorin.
b) Paranthropus.
c) Australopithecus.
d) Ardipithecus.
![Page 39: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/39.jpg)
Answer: c
• The early primitive (4.2-3.0 m.y.a.) hominids from East Africa have been named Australopithecus.
![Page 40: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/40.jpg)
Homo habilis
• A species of early Homo, well known from East Africa but perhaps also found in other regions.
![Page 41: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/41.jpg)
Early Homo Fossil Finds
![Page 42: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/42.jpg)
South African Sites
• The first australopithecine “the missing link” between apes and humans was discovered at a quarry at Tuang.
• As the number of discoveries accumulated, it became clear that the australopithecines were not simply aberrant apes.
• The acceptance of the australopithecines as hominids required revision of human evolutionary theory.
![Page 43: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/43.jpg)
Taung Child• Discovered in 1924. • The endocast is in back,
with the fossilized bone mandible and face in front.
• An endocast is a solid impression of the inside of the skull, often preserving details relating to the brain’s size and surface features.
![Page 44: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/44.jpg)
Little Foot
• Paleoanthropologist Ronald Clarke carefully excavates an australopithecine skeleton, nicknamed “Little Foot,” from the limestone matrix at Sterkfontein cave.
![Page 45: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/45.jpg)
Key South African Pliocene and Early Pleistocene Hominid Discoveries
SiteDates
(m.y.a.)Hominids
Swartkrans 1.8–1.0 Paranthropus robustus; early Homo?
Drimolen 2.0–1.5 Paranthropus robustus
Taung 2.5–2.0?? Australopithecus africanus
Sterkfontein 2.2? Australopithecus africanus; early Homo?)
![Page 46: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/46.jpg)
Steps in Interpreting Homind Evolutionary Events
1. Selecting and surveying sites.
2. Excavating sites and recovering fossil hominids.
3. Designating individual finds with specimen numbers for clear reference.
4. Cleaning, preparing, studying, and describing fossils.
![Page 47: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/47.jpg)
Steps in Interpreting Homind Evolutionary Events
5. Comparing with other fossil material—in chronological framework if possible.
6. Comparing fossil variation with known ranges of variation in closely related groups of living primates and analyzing ancestral and derived characteristics.
7. Assigning taxonomic names to fossil material.
![Page 48: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/48.jpg)
Swartkrans, Geological Section
![Page 49: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/49.jpg)
Time Line of Plio-pleistocene Hominids
![Page 50: Chapter 11](https://reader035.vdocument.in/reader035/viewer/2022062423/5681463a550346895db3458c/html5/thumbnails/50.jpg)
Groups of Plio-Pleistocene Hominids
• Specimens represent 200 individuals from South Africa and more than 300 from East Africa.
• Divided into four broad groupings: Set I. Pre-Australopithecus/basal
hominids Set II. Australopithecus/Paranthropus. Set III. Early Homo