HUMAN EVOLUTION

Classification Hierarchy

Kingdom AnimalPhylum ChordateClass MammalOrder Primates Family Hominids

Genus Homo

Species Sapiens

Important Vocabulary

Paleoanthropologist Scientist who studies

fossil evidence of human evolution.

Homininds Group that includes

humans and their immediate ancestors.

Background

It is very rare to find a complete skeleton of a fossilized hominid. Scientists need to look at many different things to try

and piece together the puzzle of human evolution.

Background Cont’d When hominid fossils are found, several important

characteristics can help determine origin and lifestyle of the species. Did organism walk upright?

Curvature of spine, position where spine attaches to skull and shape of pelvis

Brain size? Examine skull fragments

Diet? Wear and tear on fossilized teeth

How and where did it live? Fossils found in same area & environment found

Primates 2 Divisions of

Primates 1. Anthropoid

primates 2. Prosimean

primates Characteristics:

Flat Nails (no claws) Prehensile hands and

feet (grasping) Color vision and

depth perception

Anthropoid Primates Include:

marmosets Monkeys Apes Humans

Brain size Large relative

to their body size

Opposable thumbs

Similar dental formula number and

arrangement of teeth

HUMANS Bipedalism – Ability to walk on

2 feet Aligned toes = Bipedalism Enlarged brain =Vertical face Areas for speech in the brain S- shaped spine Bowl-shaped pelvis

Prosimean primates

Include: Lemurs Lorises Tarsiers

Tarsier Skeleton

Hominids

Hominids include humans and extinct humanlike primates

The oldest known hominid fossils are between 6 and 7 million years old

First fossils found in Africa

Australopithecus

Oldest known genus of hominids Lived more than 4 million years ago Knee joints- Allow bipedalism! Australopithecus anamensis Australopithecus afarensis – believed to have

given rise to: A. africanus A. robustus A. boisei

more than 1 million years ago

NOT ancestral to modern humans!

Australopithecus vs. Modern

Australopithecus, 4-3 myrs ago Modern human

Chimpanzee

A. africanus

!

A. boiser

!

Discovery of Lucy!

Fossils of nearly half complete early hominid Australopithecus afarensis

suggests hominids became bipedal before their brains began to dramatically enlarge

Ardipithecus ramidus

Recent discovery Not clear whether it was bipedal 4.4 million years old

Existence of hominid species not ancestral to modern humans implies…

Hominid phylogenetic tree is very branchy in appearance

Representing species died out, leaving no descendants.

Early Members of the genus HomoH. habilis & H. erectus

Ancestors to modern humans Larger brains than australopithecines May have had speech Started to develop tools

Homo habilis Homo erectus

Cranial Comparisons

Neanderthal Homo Erectus Homo Sapiens

Neanderthals

For years, the thinking among anthropologists was that homo sapiens, being superior to Neanderthal man, ran him off the planet. More recently, that view has been discarded and the picture become more complicated. For one thing, Neanderthals may have mixed with the ancestor of modern man, which means that we could be carrying Neanderthal genes.

Reconstructed Neanderthal skull

characterized by prominent heavy

brow ridges and week chin

Cro-Magnons

Cro-Magnons coexisted with Neanderthals in Europe and the Middle East for as many as 50,000 years

Cro-Magnons had domed heads, smooth brows, and prominent chins

30,000-year-old Cro-Magnon artifacts include: Bone flutes Ivory sculptures Evidence of elaborate burial

ceremonies

Cro-Magnon Cave Painting

Homo sapiens

Evolved about 800,000 years ago A) Neanderthals

Were early Homo sapiens They may be ancestral to modern humans OR They may have died out and been replaced by

modern humans

Some hypotheses:

1. some anthropologist think H. sapiens evolved in PARALLEL from populations of H. erectus all over the world. (interbreeding)

2. some anthropologists propose that H. sapiens DESCENDED from H. erectus in Africa and then dispersed across Earth.

Evolution of Modern Humans

Human Evolution

Piltdown Man (1912)Charles Dawson fake 1953

preceding Neanderthals

*

Waves of Hominid Emigration

Two hypotheses have been proposed for the evolution of Homo sapiens “African replacement” hypothesis

Also called Out of Africa, Recent-African-Origin “Multiregional origin” hypothesis

“African Replacement” Hypothesis

Members of the genus Homo made repeated long-distance migrations out of Africa beginning 1.8 million years ago

H. sapiens emerged from Africa about 150,000 years ago and spread across the Near East, Europe, and Asia

The dispersing H. sapiens populations replaced all other hominids

Evolution of Modern Humans

“Multiregional Origin” Hypothesis

H. erectus emerged from Africa 1.8 million years ago and spread across the Near East, Europe, and Asia

Continued migrations and interbreeding occurred among widespread H. erectus populations

Regional populations of H. erectus evolved into H. sapiens

Evolution of Modern Humans