2 Divisions of Primates 1. Anthropoid primates 2. Prosimean primates Characteristics: Nails (no...

HUMAN EVOLUTION

Primates 2 Divisions of

Primates 1. Anthropoid

primates 2. Prosimean

primates Characteristics:

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

Gorilla Skeleton

Human Skeleton

Skeleton Comparisons

Draw a Prosimean skeleton, Anthropoid skeleton and a human skeleton

Draw the basic bones Pay special attention to the skulls

Use the same colors for homologous parts in the three skeletons

Highlight the key features of each primate that makes them successful and unique

How does this make them successful?

PALEOANTHROPOLOGISTS

Scientists who study fossil evidence of human evolutionConstruct models of how and when different stages of human evolution occurred

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

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

“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

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 Modern Homo sapiens

more than 1 million years ago

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 erectus- potential first hominid to leave

Africa Homo habilis Homo erectus

Neanderthals

Now extinct Hypothesis- Homo sapiens, being superior to

Neanderthal man, ran him off the planet. New hypothesis- more complicated

Neanderthals may have mixed with the ancestor of modern man

We could be carrying Neanderthal genes. Heavy bones Thick brow ridges Protruding teeth Used shelters, tools, and clothing

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.