Climate and Human Evolution; the last

4.6 billion years

By Kristin Hepper                                                                   

Time gone by…

Earth is 4.5 billion years old

Archaean Era 3800 to 2500 million years ago

Proterozoic Era 2500 to 544 million years ago

Stromatolites

Ice Ages

Huronian Ice Age- 2.3 billion years ago

Gnejso Ice Age- 950 million years ago

Sturtian Ice Age- 750 million years ago

Varangian Ice Age- 600 million years ago

Muir Glacier at Glacier Bay, 1971

Phanerozoic Eon

Archaean Era, Proterozoic Era, Phanerozoic Eon

544 million years ago to the present Divided into three Eras

Cenozoic 65 million years ago to the present

Mesozoic 248 to 65 million years ago

Paleozoic 544 to 248 million years ago

Pangaea- one supercontinent300-200 million years ago

Laurasia and Gondwanaland

Triassic- 200 mya

Say Goodbye to Pangaea…

Jurassic

Cretaceous

But, they are still moving….

The question is…where are they going?

Just one hypothesis…

Now that we are at the present, let’s jump back 5 million years…

To the Pliocene 5-1.8 million years ago

What is going on? Antarctic ice sheet melts back significantly Climate is oscillating Tethy’s Seaway

What about our ancestors?

Earliest known hominoid- Proconsul africanus 16 mya East Africa

Divergence from the great

ape lineage 5 mya Timing estimated from

molecular clock

Ardipithecus ramidus (Pliocene)

From Aramis in Ethiopia

5.5-4.4 mya

Primitive dentition

Oldest taphonomically determined example of australopithecines

Maybe the missing link???

Ardipithecus ramidus: upper right molar

Australopithecus anamensis (Pliocene)

Lake Turkana, Kenya 4 mya More adaptations to

bipedality

Australopithecus afarensis (Pliocene) Known to the world

as “Lucy” Hadar, Ethiopia Varied from 1-1.7 m

in height and 25-50 kg in weight

Ate fruits and nuts and some meat while living in a wooded environment

Brain size- 415 cc’s

Laetoli Footprints- Tanzania

Preserved in volcanic tuff erupted out of Mt. Sadiman to the east, which is dated back to 3.7 mya.

75 ft long

69 total prints

Australopithecus africanus (Pliocene) The Taung Baby

Material comes from all over Africa Sterkfontein, Makapansgat, and Taung

3-2.4 mya Has more derived characteristics Lived in a more open environment and

maybe used underground resources such as roots

Brain size- 450 cc’s

Pleistocene- 2 mya-10,000 ya

Biotas were similar to modern ones

Characterized by distinctive large animals

Global oscillations of ice sheets Global oscillations of

productivity Humans…here we come!!! Glacial maximum

Homo habilis (Pleistocene) First appearance of

Homo 2.4 mya

Olduvai Gorge, Tanzania

Brain size- 590-710 cc’s

Specimens show high variability of traits

Stone tools

Homo ergaster (Pleistocene)

Lake Turkana, Kenya; Olduvai Gorge, northern Tanzania

1.8 mya

Big brain- 900 cc’s

Very human-like body

Associated with tools

Homo ergaster

600,000 to 400,000 years ago Homo heidelbergensis

Around 600,000 ya hominids start

Showing some differences from H. ergaster

Had larger brains 1200-1250 cc’s

Out of Africa

Remember…

Out of Africa- what was happening in Africa in the Plio-Pleistocene

Habitats were unstable Grasslands were expanding and contracting Climate is oscillating

Homo neanderthalensis Neander Valley,

Germany

200,000 to 35,000 ya in Europe and W. Asia

Tools

Burial

Had thick brow ridges

Human Neanderthal

Brain Size1300 cc’s

Homo sapiens

Anatomically modern Homo

Africa: 100,000 to 90,000 ya

50-45,000 ya evidence of culture

Reach Australia between 50,000 and 35,000 ya

Homo sapiens

35,000 ya adapted to cold Siberia and Alaska

14,000 ya crossed the land bridge into the Americas

Islands of Pacific were settled around 3,000 ya

New Zealand was the last 1200 A.D.

Features of Homo sapiens

Big brains 1500 cc’s

High foreheads

Face is flat and pushed in

Small brow ridge

Long limbs