becoming human part 1 nova. early hominoid – where to look? rift valley of east africa southern...

BECOMING HUMAN PART 1• NOVA

Early Hominoid – Where to Look?Rift Valley of East Africa

Southern Africa

3 Major Groups

Pre-australopiths (7-4.4mya)

Australopiths (4.2- 1 mya)Early Homo

(2.4 – 1.4)

How far back?

7 – 8 million years

70% of our history resides in Africa

Extensive changes in the last 10 years1992 3-4 million1998 4.4 2000 62003 7 million

Lucy 3.7 –3.5 mya

Don Johanson Dicovered in Hadar in 1974

Lucy in combination w/ Leakey footprints tell us about locomotion and stature

Lucy 40% of skeleton, one of three most complete, Pre-100,000

Accurate Dates due to Volcanic Ash layers

Laetoli (Ash Footprints)

Discovered in 1978

1. Convergent Big Toe

2. Clearly Bipedal

3. Arch

4. Slow Moving “Strol”

5. Short Stride

Laetoli (Ash Footprints)

Chapter 9

The Earliest Dispersal of the Genus Homo: Homo erectus and

Contemporaries

Left: Homo Erectus (1mya)Center: Australopithicus afarensis (2.5mya)

Right: Homo Neandertalensis (100,000-32,000ya)

BECOMING HUMAN PART II• NOVA

First Dispersal of the Hominins• Close to 2 million years ago, hominins

expanded out of Africa into other areas of the Old World.

• Since the early hominin fossils have been found only in Africa, it seems that hominins were restricted to this continent for as long as 5 million years.

First Dispersal of the Hominins• After 2 mya, there’s less diversity in these

hominins than in their pre-australopith and australopith predecessors.

• There is universal agreement that the hominins found outside of Africa are members of genus Homo.

• Homo erectus is the species for which there is the most evidence.

Homo erectus – A New Kind of Hominin

• The first hominin to expand into new regions of the Old World.

• As a species, H. erectus existed over 1 million years.

• We can understand its success as a hominid species based on behavioral capacities (i.e.) more elaborate tool use) and physical changes (i.e. larger).

Acheulian Biface Acheulean tools are typically

found with Homo erectus remains.

Lower to Middle Pleistocene • A basic tool of the Acheulian

tradition.• Acheulian tool kits are common

in Africa, southwest Asia, and western Europe, but they’re thought to be less common elsewhere.

Homo erectus

• Discoveries from East Africa have established Homo erectus by 1.8 m.y.a.

• Some researchers see anatomical differences between the African and Asian discoveries. – They place African fossils into the Homo ergaster

species.• Analyses show that H. erectus/ergaster represents

closely related species and possibly geographical varieties of a single species

Grade• H.erectus hominins represent a different grade of evolution

than their African predecessors.• Grade refers to a grouping of organisms sharing a similar

adaptive pattern.• Grade implies nothing directly about shared ancestry, but

implies general adaptive aspects of a group of animals

Morphology of Homo erectus • Living in different environments over much of

the Old World, H. erectus populations shared several common physical traits including…

Body Size• Adult weight >100 lbs,

average adult height of ca. 5 feet 6 inches

• Sexually dimorphic, weight and height varied according to sex

• Increased robusticity (heavily built body) that dominated hominin evolution until anatomically modern H. sapiens