Chapter 11 Hominid Origins in Africa. Major Events in Early Primate Evolution

Chapter 11

Hominid Origins in Africa

Major Events inEarly Primate Evolution

Miocene Hominoid Distribution, From Fossils Thus Far Discovered

Miocene Fossil Hominoids1. African forms (23–14 m.y.a.)

• Western Kenya• Primitive.

2. European forms (16–11 m.y.a.) • France, Spain, Italy, Greece, Austria,

Germany, and Hungary.3. Asian forms (16–7 m.y.a.)

• Largest and most varied group• Turkey through India/Pakistan and east to

southern China.

Miocene Hominoid Fossils1. These are hominoids.2. Mostly large-bodied hominoids.3. Not (certainly) ancestral to any living form.

One lineage that appears well established relates to

4. Sivapithecus from Turkey and Pakistan. 5. Evidence of definite hominids from the

Miocene has not yet been indisputably confirmed.

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

Features of Australopithecus

1. Bipedal.

2. Small brains.

3. Large teeth, & thick enamel on the molars.

Laetoli Dated at between 3.5 and 3.7 m.y.a. Fossilized hominid footprints were found

in an ancient volcanic bed. Bipedal locomotion.

Hadar (Afar Triangle) Dating range- 3.9 to 2.3 m.y.a. Recovered:

"Lucy" 13 individuals, including 4

infants (social unit died at the same time).

Some stone tools (2.5 m.y.a., earliest cultural evidence)

Koobi Fora (East Lake Turkana) Richest assemblage of Plio-

Pleistocene hominids in Africa.

Most date to 1.8 m.y.a., others to 3.3 m.y.a.

150 hominid specimens represent at least 100 individuals.

West Turkana Two important discoveries:

Almost complete 1.6 m.y.a. Homo erectus adolescent.

“The black skull”, a well-preserved 2.4 million year old skull.

Olduvai Gorge Louis and Mary Leakey excavations

(1930's to early 1980). Evidence of over 150 species of extinct

animals.

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.

Groups of Plio-Pleistocene Hominids 200 individuals from South Africa Over 300 from East Africa. Divided into four broad groupings:

Set I Basal Hominids. Set II Early Primitive Australopithecus. Set III Later, more derived

Australopithecus. Set IV Early homo.

Set I. Basal Hominid(4.4 m.y.a.)

Aramis- earliest and most primitive remains.

Classified as Ardipithecus ramidus.

Set II. Early Primitive Australopithecus, 4.2-3.0 m.y.a.

Australopithecus afarensis – Laetoli & Hadar hominids

A. afarensis very primitive, criteria for classification as hominid is bipedalism.

Set III. Later, More Derived Australopithecus (2.5-1.0 m.y.a.)

Robust Australopithecines Larger body size Small cranial capacities Very large, broad faces Massive back teeth and lower

jaws Gracile Australopithecines

Different face dentition

Set IV. Early Homo (2.4-1.8 m.y.a.)

The earliest appearance of our genus, Homo may be as ancient as the robust Australopithecines.

Leakey named these specimens Homo habilis ("handy man")

H. habilis differs from Australopithecus in cranial cavity and dental proportions.