Transcript Chapter 11

Fossil Evidence
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Fossils- any traces of dead organisms
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dinosaur bones
insects trapped in tree sap
leaf impressions
footprints
Fossil Evidence
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Transitional species- species that have been
found in the fossil record that are
intermediates between two other species in
the evolutionary process.
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Radiometric dating- a dating technique that measures amount
of radioactive material in a rock or fossil.
Relative dating- a dating technique that estimates the date of
a fossil by relating it to the age of the layers of rock around it.
Fossil Evidence
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To fossilize an organism
must be buried by
sediment.
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In swamps, mud, tar pits, or
the ocean bottom.
Hard stuff fossilizes
(bones, nails).
Radiometric and relative
dating are used to find out
how old the fossil is.
Relative
Dating
Radiometric
Dating
Fossil Evidence
Fossils show:
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Life has been around for millions of years
Transitional species link older to newer species
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Darwin proposed the idea of transitional species,
though he had no evidence
Today we have evidence:
• Archaeopteryx
• Whales
Fossil Evidence-Archaeopteryx
WINGS
BEAK
Fossil Evidence
 Whales--60
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million years of evolution
Descended from 4-legged wolf-like
animals that were also ancestors to
cows and horses
Fossil evidence shows slow loss of legs
Pelvis still remains with no rear legs
Fossil Evidence-Whales
Whale Video
 Earth
is estimated to be about 4.6 billion
years old.
 Atmosphere was harsh.
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Very Hot.
Lots of water vapor
Volcanoes
NO BREATHABLE OXYGEN GAS!
CO2, ammonia, methane present
Origin of Life
Stromatolites
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Scientists had hard time
finding evidence of early
life.
45 years ago we found out
why….
Most ancient life was
microscopic=microfossils in
stromatolites.
1st organisms to evolve
were prokaryotes
Oldest microfossil3.5
billion years old
Cyanobacteria fossil about
1,000,000,000 (1 billion)
years old found in stromatolites
Origin of Life’s Chemicals
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Miller-Urey
Hypothesis: Can organic
compounds form in early
Earth conditions?
Experiment recreated
atmosphere of early Earth
Results: building blocks of
life were formed.
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Amino acids (proteins)
Nucleotides (DNA, RNA)
Lipids
Carbohydrates
Self Assembly
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Some molecules can
spontaneously form into
droplets
 Solution with lipids and
proteins will self assemble
into a lipid bilayer like a cell
membrane
 First cell membrane and
beginning of prokaryotic life
took 1 billion years.
 What else is needed for life?
1st genetic material- RNA
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Earth’s early surface was inhospitable
due to immense UV radiation
 Deep sea vents may have provided
sheltered location for life.
 Oldest living prokaryotes found there
today…
 RNA can form under conditions similar
to deep sea vents
Road to Modern Organisms
1st life was bacteria unicellular prokaryotes
Cyanobacteria- photosynthetic blue-green prokaryotes
later changed Earth’s atmospherereleased O2!
2nd was unicellular eukaryotes Endosymbiotic
Theory
3rd was multicellular organisms
Classification/Evolution
6 Kingdoms
Classifying Living Things
 Carl Linnaeus was a
scientist who developed a
classification system for
living things.
 Wrote book Systema
Naturae in 1735 to
reveal his classification
system.
How biologists classify
 1. Comparing morphology
(physical traits)
 2. Looking at genetic
similarities & differences
 3. Biochemical make-ups
 4. Behavioral similarities
 Origin of Life Video
Cladograms
 Cladogram- a branching diagram that shows
evolutionary relationships.
 We use taxonomy – the science of classifying
living things, to help us determine the
cladogram.
Scientific Naming
 Binomial nomenclature- unique 2-word
naming system used by scientists.
 1st word is the genus, 2nd is the species.
 Genus- group of organisms that share
similar characteristics.
 Panthera leo-lion
 Panthera pardus-leopard
 Species- group of organisms that can
successfully breed within their group,
but not others.
How to write a scientific
name
 Genus is always capitalized
 Species is always lower
case
 The whole name is
underlined if written or
italicized if typed.
 Example: Homo sapiens
Examples
 Homo sapiens:
 Homo = genus
 sapiens = species
 Common name = humans
 Quercus rubra–
 Quercus = genus
 rubra = species
 Common name = red oak
 Scientific names are in Latin b/c scholars in the
Middle Ages communicated using it!
6 Kingdoms
 There are six kingdoms all living
things are classified into:
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Animals
Plants
Fungi
Protists
Eubacteria
Archeabacteria
Classification
 Scientists have determined
seven levels of
classification:
 Kingdom = Kings
 Phylum = Pass
 Class = Classes
 Order = to Order
 Family = Families
 Genus = and their Good
 Species = Sons around
Classification of Modern
Humans
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Kingdom = Animalia
Phylum = Chordata
Class = Mammalia
Order = Primates
Family = Hominidae
Genus = Homo
Species = sapiens
Evolution of Primates
Primate- mammal with 5 flexible
fingers
Earliest dwelled in trees-arboreal
Needed special adaptations for
this:
– Opposable thumb….Why?
– Binocular vision- eyes in front
of head in which field of vision
of eyes overlap—depth
perception….Why?
– Rotating Shoulders
Evolution of Humans
Vocab:
– Bipedal- walk upright on two legs
– Hominid- bipedal primates such as
humans and their closest fossil relatives
Hominids
Hominids are the ONLY bipedal primates:
– Locking knee joints
– Spine enters skull at
bottom of head
– Femurs (thigh bone)
tapers in
– Big toe in line with
others
Laetoli Footprints
Hominid vs. chimpanzee
Chimps most closely related primate to
humans—95% similarity in the sequence of
our genes!
Human’s jaw arc shaped with smaller
canines; chimps’ are U shaped with
larger canines and larger gaps.
Hominid vs. chimpanzee
Hominid spine S–
chimps’ is C shaped
Hominid pelvis is
bowl-shaped, chimps’
long
Hominid thigh bones
taper in—chimps’ out
Human Evolution
Video Clip
Early Hominids
Genus Australopithecus
– LucyAustralopithecus afarensis
– Fossil found in Africa
– They were hominids
Shape of pelvis and femurs showed
they were bipedal.
Locking knee joints
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Short—3’6’’
Brain size of chimps
Jaws more rounded than apes
Teeth like humans
LUCY
3.5 million years old
40% complete
Female
Showed us:
– Walked upright first
– Brain size grew
LATER.
SKULLS
A. afarensis (Lucy)
Homo sapien
SKULLS
Lucy had a small skull like an
ape, but she wasn’t one.
LUCY
APE
LUCY VS. APE
Homo habilis
Means: Handy man
Small structure like
Lucy
Skull 2X’s the size
of Lucy
2- 1.8 mya in
Africa
Tools made of
bone and stone.
Homo erectus
Peking man
Africa / Asia / Europe
Larger than H. habilis
Larger brain
Excellent tools, used fire
1.5 mya – “immediate”
ancestor
Where Did H. sapiens evolve?
Out of Africa
hypthothesis- idea
like Darwin’s which
states H. sapiens
evolved IN Africa H..sapiens
and spread to rest of
H. erectus
world
Out of Africa
hypothesis
supported by fossils
of modern-like
humans found in
Africa
Early H. sapiens
Homo neanderthalensis discovered in Neander
Valley in Belgium
Massive skulls and
protruding brows
400,000-100,000 years ago
Early H. sapiens
Great controversy: did
they die off (genes no
longer) or did they
interbreed with us so their
genes are still in our gene
pool?
Modern H. sapiens
probably evolved in Africa
and replaced Neanderthals.
APES
Mated????
Homo neanderthalensis Homo sapiens
transitional species
Homo erectus
Homo habilis
Australopithecus
afarensis
common ancestor to
ape and H. sapiens