Human Evolution

Evolution of Homer

I. Background Info

A. Primates1. Evolved ~65 million years ago2. Current members include lemurs, lorises,

pottos, tarsiers, monkeys, and apes (lesser and greater), etc.

3. Apes differ from other primates in that they lack prehensile tailsa. Lesser apes - gibbonsb. Greater apes (hominoids) – chimps,

orangutans, gorillas, bonobos, and HUMANS

DRAW Fig 32-15, pg. 834

B. Trends in Primate Evolution

1. Hair and nails instead of fur and claws.2. Five digits with an opposable thumb.3. Well developed cerebrum.4. Binocular vision (both eyes in front

improved depth perception) and retina with both rods and cones for color vision.

5. Reduction in the sense of smell.6. Longer period for parental care and

learning.7. Uprightness

a. Freed the hands to develop and use toolsb. Gave better vision (higher up and straight

forward)

Primate Evolution Movie

II. Hominid EvolutionA. About 4 million years ago, ancestors of

humans and apes divergedB. Hominids include modern humans and

extant human-like formsC. Evolved with bipedal motion (walk

upright) and larger brains

Modern Gorilla

Comparing Human and Gorilla Skeletons

Modern Human Modern Gorilla

Skull atopS-shaped spine

Spinal cord exitsat bottom of skull

Arms shorter thanlegs; hands do not touch groundduring walking

Pelvis is bowl-shaped

Thigh bones angledinward, directlybelow body

Skull atopC-shaped spine

Spinal cord exitsnear back of skull

Arms longer thanlegs; hands touch ground during walking

Pelvis is longand narrow

Thigh bones angledaway from pelvis

In 1978, members of a team led by Mary Leakey discovered the fossilized footprints of human

ancestors in Laetoli, Africa. The footprints were formed 3.6 million

years ago when at least two individuals walked over wet volcanic ash. The wet ash

hardened like cement and was then covered by more ash. The footprints show that the individuals had perfect, two-

footed strides. They also reveal that one hominid was larger than

the other. The imprints left behind at Laetoli clearly show the weight distribution of true upright

walkers.

Laetoli Footprint Movie

D. About 20 different species of hominid fossils categorized so far

E. Many are not direct ancestors of humans 1. Tree of life has many dead end branches

Hominid Evolution Timeline

F. Trends in hominid physical traits toward Homo sapiens

1. Jaws and teeth are smaller2. Cranium (skull) is larger3. Forehead is less sloped4. Hips are wider

G. Dispelling misconceptions about Homo sapiens1. Did not evolve from monkeys2. Did not co-exist with dinosaurs3. Humans evolved like every other species on

Earth

III.Some Hominid Species

A. Sahelanthropus tchadensis1. Oldest known hominid fossil (7 million

years old) named “Toumai” found in Chad, Africa

2. Primitive ape-like features (small brain size - 350 cc) mixed with later hominid features (small canine teeth and brow ridges)

3. Thought to be close to original ancestor of chimps and humans, as it is from time apes and hominids diverged

Toumai Movie

B. Australopithecus afarensis (3-4 mya)1. ~ 300 fossils found, “Lucy” is most famous2. Lived in Eastern Africa in savanna woodland3. Features:

a. Apelike, 1 meter tall, ~50 lbsb. Lived in groups, ate fruit, nuts, seedsc. Bipedal with locking knees

4. A direct relative

Australopithecus Afarensis Movie

C. Homo habilis (1.5 - 2 mya) 1. Lived in eastern Africa, savanna woodland 2. Features:

a. more humanlikeb. smaller jaw and teethc. diet: generalized diet, included meatd. “handy man” – used simple stone tools for

scavenging large animals (bone marrow) and preparing vegetables

3. a direct ancestor or close “cousin”

D. Homo erectus (1.8 million – 300,000 years) 1. Originated in Africa were nomadic and migrated

into Asia and Europe2. Features:

a. More human like but still had many ape-like features

b. Much larger brain than previous hominidsc. Worked cooperatively and hunted large

animals.d. Extremely stronge. Used advanced tools (hand axe and fire)

3. A cousin

E. Homo neanderthalensis (200,000 – 30,000 years ago)

1. Location: Siberia, Europe & Middle East, cold woodlands and tundra (Ice Age)

2. Lived at the same time as early Homo sapiens

3. Featuresa. Short, stocky bodiesb. Large brain, large brow bone, no chinc. Reliance on meat, some vegetables d. Purposeful burial of deade. Used simple “language” - FOXP2 gene

allowing for complex speech and language

4. DNA studies do not show Neanderthals to be direct ancestors of modern humans, but our genes differ by only 0.5%Extra Credit: Read National Geographic

article about Neanderthals and complete 8 question online quiz

Skull Comparison of Hominids

Australopithecus afarensis Homo erectus

Neanderthal Cro-Magnon Modern Homo sapiens

Large braincase

Large browridge

Large nose

Face protrudesforward

Large canineteeth

Weak browridge

Inflatedcheeks

Largenose

Strong chin

Even teeth

Round, highskull

HUMAN FAMILY TREE

Human Family Tree

F. Homo sapiens (195,000 y.a. – present)

1. Location: from Africa then migrated, reached Australia 60,000 years ago, North & South America 12,000 - 20,000

2. Features:a. Lighter skeletal buildb. Large brain (1350 cc)c. Small eyebrow ridged. Prominent chine. Larynx in the throat is lower allowing for

complex language

3. FOXP2 gene (evolved ~100,000 y.a.)

4. Cro-Magnon man (40,000 years ago)a. “caveman”

b. gene microcephalin, which increases brain size, shows up at 37K y.a.

c. sophisticated culturei. tools of bone and antlers, clothing

ii. cave paintings, sculptures, musical instruments, jewelry

Cro-magnon cave paintingsMammoth ivory flute

5. DNA evidence

a. Mitochondrial DNA (mtDNA) is passed from mother to child

b. Y chromosome is passed from father to son

c. Areas of both the Y chromosome and mtDNA get occasional harmless mutations at a constant rates that are called “markers”1) We can calculate when and where a genetic

marker occurred 2) By comparing genetic markers to those of native

peoples today, it tells us when in time the mutation occurred and the migration patterns of hominids

Human DNA Movie

Homo sapien Migration