The Theory of
Evolution
A theory…
Explains the current observations and
predicts new observations.
Present day organisms are similar,
but not identical, to fossil organisms.
•Explain this observation
•What predictions can we make?
•We should see observable differences and
similarities between fossils and living
things.
•Others?
A Theory…
What types of evidence would help
us confirm these predictions?
•Fossils
•Embryology
•DNA sequence
•Similar Body Structures
Variation & Adaptation
OBJECTIVES:
• Define species
• Distinguish between variation and
adaptation
• Understand the concept of a niche
• Explain how fossils are used to study
ancient life forms
What is a species?
A species is a group of organisms that can mate
and produce fertile offspring.
Recall: Species
• Organisms that can mate and produce
fertile offspring.
• Variation can exist within a species:
– Polymorphism- 2 or more distinct forms.
Ex; peppered moth; males and females.
– Geographic variation – Unique local
environments favor particular traits.
– Individual variation
Variations can be dramatic (fur color of
foxes) or subtle (different blood types
of penguins)
Most variations are genetically
determined and therefore inheritable.
These inherited variations are the result
of two random processes:
1) Mutation –
a change in genetic information
2) Recombination –
shuffling the genes or alleles
Genetic Determination of
Variations
• Mutations: Changes in sequence of
DNA bases. May occur during
– replication
– meiosis
Sickle Cell Anemia
Mutation in the gene
that codes for
hemoglobin.
Beneficial in some
environments
because being
heterozygous for
sickle cell = immune
to malaria
Most variations, however, result not from
mutations but instead from the
RECOMBINATION of existing alleles.
Alleles can be recombined by three
different mechanisms.
1) Independent assortment of
chromosomes
2) Crossing-over during meiosis
3) Combination of genes from egg &
sperm
ADAPTATIONS
Variations create a population with
diverse traits. These traits ultimately
determine whether an individual will
survive in an environment.
An adaptation is an inherited trait that
increases a population’s chances of
survival and/or reproduction in a
particular environment.
Adapatations are traits that
help organisms survive in
their niche. Therefore all
members of the population
possess the trait
(adaptation).
All giant anteaters have the same
noticeable adaptations.
1) long snout
for prodding ant hills
2) long tail
for balance
3) sharp claws
for tearing through
(Myrmecophaga tridacttyla)
termite mounds
AND
4) long sticky
tongue
for capturing
insects
Types of Adaptations
Anything that helps an organism
• Hide from/defend against predators
• Attract a mate/reproduce (sexual
selection)
• Catch food
Broadly speaking, a niche is a habitat and
the role a population plays in that habitat.
A niche includes where organisms
live, what and how they eat, how
they raise their offspring, and
what their predators are.
When niches overlap, competition
ultimately results.
Lions & hyenas
Summary of
Variation & Adaptation :
1) Most variation in a population results from
mutation and recombination of existing
alleles.
2) Some variations are adaptations that
increase a population’s chances for survival
and reproduction.
3) Each species in an environment has its own
niche. Niches are created and destroyed by
environmental changes.
Darwin and His Theory
OBJECTIVES:
• Explain the theories that led to the theory
of evolution.
• Understand the importance of Darwin’s
Voyage on the HMS Beagle.
• Analyze Darwin’s theory of evolution by
natural selection
• Distinguish between gradualism and
punctuated equilibrium
Beginning in the late 1700’s paleontologists
were beginning to discover fossils of
animals that no longer existed.
Charles Bonnet
1769, Swiss naturalist
Observed that fossils do not
resemble modern organisms.
Theorized periodic
catastrophes: affect the
entire planet killing all life,
which began anew after each
catastrophe.
First to use the term
“evolution” to mean change
over time.
Jean-Baptiste Lamarck
Lamarck believed that
fossils of extinct
animals were the
ancestors of animals
living today.
1. Organisms constantly strive to
improve themselves.
2. The most-used body structures
develop, unused structures waste
away. “Use and Disuse”
3. Once a structure was modified by use or disuse,
modification is inherited by offspring. This third
principle is called the “inheritance of acquired
characteristics
(Lamark stated that a giraffe’s neck gradually became longer
due to stretching it during its lifetime. Their longer necks
could then be passed on to their offspring.)
Lamark’s
hypothesis
about the
inheritance of
acquired
characteristics
was later
disproved by
German
biologist
August
Weismann
Through experiments with
mice, Weismann concluded that
changes in an individual during
its lifetime
DO NOT
usually affect its reproductive
cells or its offspring.
Darwin’s
Story
On January 10th, 1831, Darwin just 22 years
old, set sail around the world on the H.M.S.
Beagle as .its naturalist. The voyage lasted
longer than he expected. He returned to
England five years later!
.
The Voyage of the Beagle (1831-1836)
The Beagle’s mission was to undertake a survey voyage to
South America in order to produce more accurate maps.
One of the locations they visited
that influenced Darwin the most
was the Galapagos Islands.
“They are situated under the
equator, and between five and six
hundred miles westward of the
coast of South America.”
Aboard the “H.M.S. Beagle”, Darwin spent five weeks exploring
the Galapagos Islands
Each of the islands, although having similar climates and
environments and being only about 50 miles apart, has its own
fauna and flora - similar to but distinct from those of the
neighboring islands. This suggested to Darwin that the similar
species might have developed from a common ancestor rather
than each having been created separately.
Influences
on
Darwin
The Earth is very
old.
Thomas Malthus
“Human populations are
growing so fast, that
the supply of resources
cannot keep up with
demand. This results in
war, starvation and
disease.”
Darwin realized that
this principle applied to
all species, not just
humans.
Thomas Malthus
(Population Biologist)
All
organisms
compete for
resources.
“In October, 1838, I happened to read Malthus for amusement. Being
well prepared to appreciate the struggle for existence, which everywhere
goes on, from long continued observation of the habits of animals and
plants, it at once struck me that under these circumstances favorable
variations would tend to be preserved and unfavorable ones to be
destroyed. The result of this would be the formation of a new species.”
Artificial Selection
Evolution can be seen experimentally
through artificial selection.
Artificial Selection is an
experiment in Quantitative
Trait Loci
A single trait affected by multiple
genes and measured on a continuous
scale.
Ex: size, feather color, weight
Over generations of artificial selection,
gene pool is altered. Several genes
are affected.
Corn has been selected to produce
larger and larger ears over the
past 200 years.
All dogs breeds were created from wolves by
humans over a 10,000 year period.
Darwin’s Theory of
“Natural Selection”
1. There is variation within
populations. Some
variations are favorable.
2. More offspring are born
than can possibly survive
due to limited resource.
3. Individuals that survive
and reproduce are those
with favorable traits.
1858, Darwin received a
manuscript from
Alfred Russel Wallace entitled
“On the Tendency of Varieties to
Depart Indefinitely from the
Original Type.” Wallace had
independently reached the same
conclusion that natural selection
had played a major role in the
origin of new species. Dismayed,
Darwin offered to withdraw his
own manuscript, but a joint paper
by the two men was read before
the Linnaean Society of London on
July 1, 1858.
Wallace had also gone on an observational expedition
to an area of the world filled with isolated islands.
On November
24, 1859,
Darwin’s
book,
“On the
Origin of
Species ”
is published.
Chapter 16
Population Genetics
•
•
•
•
•
OBJECTIVES:
Relate the study of genetics to that of
population genetics and discuss factors that
can affect gene-pool equilibrium
Explain the Hardy-Weinberg model
Discuss evolution through natural selection
Explain genetic drift and contrast its
effects on large and small populations.
Discuss the role of quantitative traits in
microevolution.
Population Genetics
Recall: variation among individuals
allows populations to adapt to new
environmental conditions or to be
selectively bred for desirable
traits.
2 Types of Evolution
• Microevolution: change within a
species. Occurs over dozens or
hundreds of generations*
• Macroevolution: Much longer time
period. Results in a new species
A More Precise Definition
Microevolution is a change in the
genetic composition of
populations.
Studied by population geneticists.
Gene pool
All alleles in a population of
organisms.
Allele frequency
Percentage of a particular allele in
one population.
Ex: In a population of pea plants
that are all homozygous for purple
flowers, allele freq. for purple
flowers is 100%
A change in an allele frequency is an
indication of evolutionary change.
Allele Frequencies within
Beetle Population
Polymorphic Populations
• Have 2 or more alleles for a
particular trait.
• Ex: humans are polymorphic for blood
type.
• Ex: apple trees are polymorphic for
fruit color.
Hidden Genetic Variations
• Mutation in non-coding regions of
DNA
• Silent mutations code for the same
amino acid
• Unseen polymorphisms
The Hardy-Weinberg Model
An idealized mathematical model of gene
pools.
•Mathematician Godfrey H. Hardy
•Physicist Wilhelm Weinberg
Hardy-Weinberg Equilibrium
Allele and genotype frequency will stay
constant in the absence of disturbing
influences.
p2 + 2pq + q2 = 1
• Good news for Darwin! (Assumed
blending inheritance.)
Hardy-Weinberg Model
Makes some assumptions about the
population. No “disturbing influences.”
• random mating
• no mutation (the alleles don't change)
• no migration or emigration
• infinitely large population size
• no selective pressure for or against
any traits.
Hardy-Weinberg Equilibrium
Predictions of the model
1. Predicts allelic and genotypic
frequencies
2. Genetic variation remains in the
population (unless selective
pressures)
Genetic equilibrium: a constant
state of allele frequency
The following conditions must be met in order that
genetic equilibrium not be disrupted.
1) No natural selection
2) Random mating
3) No migration
4) No mutation
5) Large population size
Note: does not occur in nature.
So, why use Hardy-Weinberg model?
Quick Quiz
1. Would a change in allele frequencies
be more likely to produce
microevolution or macroevolution?
2. What is the difference between
gene pools and allele frequencies?
3. Why does the concept of gene pools
apply to populations but not to
species?
A Normal Distribution
results from
Stabilizing Selection:
Natural selection that
favors average
individuals in a
population.
Disruptive Selection:
Natural selection
that favors either
extreme trait.
Disruptive Selection in Snails
Limpets with light-colored shells blend in
with light rocks and sand. Dark shells blend
in with dark rocks.
Limpets with medium-colored shells are easily
seen on both rocks and eaten by birds.
Disruptive Selection in Spiders
• When spiders are small, they are not
as easily seen by predators.
• When spiders are large, they are
often too big to be eaten.
• Spiders in the middle are the most
vulnerable to predators.
Other Factors Affecting Gene
Pools
• Gene Flow: Migration to a new
population, organism may bring new
alleles with it.
• Mutation: If beneficial, will be
favored by natural selection and
gradually increase in frequency
• Genetic Drift: Spontaneous changes
in allele frequencies. Small
populations only.
Other Factors Affecting Gene
Pools
• Inbreeding: Gradual increase of
homozygotes. Ex: California Condor
• Population bottleneck: Population size
reduced for a few generations.
Inbreeding results. Ex: Buffalo in the
1800’s.
• Inbreeding increases frequency of
harmful recessive alleles. Leads to
Inbreeding Depression: reduced fertility
and survival.
Did you know…
The average human is estimated to
have 7 alleles that would be lethal if
they were homozygous? In inbred
populations, inheriting 2 of these
alleles is more likely.
(BSCS Biology: A Molecular Approach)
Population Genetics
CONCEPT REVIEW:
• Evolution results from a disruption in genetic
equilibrium.
• The normal distribution of variations in a
population can be changed by natural
selection, gene flow, mutations, and genetic
drift
Chapter 17
The Origin of Life
Objectives:
• Describe the origin of the universe and
probable conditions on early Earth
• Evaluate hypotheses about the origin of
life and identify the probable
characteristics of early life-forms
• Distinguish between chemical and
biological evolution
• Describe the fossil record for
prokaryotes and eukaryotes.
The Big Bang
The Expanding Universe
• Edwin Hubble, 1920. The Hubble
Telescope was named for him.
• Wavelengths of light can be
measured, spread out as objects move
farther away
• The rate of expansion is known, used
to calculate the time when universe
was tiny.
The Big Bang
• 15 million years ago
• Universe was condensed into a tiny
“singularity”
• An infinitely hot, dense mass.
• When it exploded, The Big Bang,
hurled energy and mass into space.
• What was there before the Big Bang?
Early Earth
• 4.6 Billion years ago
• Meteorites and the oldest rocks from
the Moon confirm this
History of the Earth
Era
Million Years Ago
First evidence of
Cenozoic
7-5
65
Human-like apes
Primates
Mesozoic
140
220
235
Flowering Plants
Mammals
Dinosaurs
Paleozoic
300
360
400
430
520
Reptiles
Amphibians
Land Animals
Land Plants
Vertebrates
Precambrian 2100
2500
3500
Eukaryotes
Free O2 in atmosphere by prok.
Prokaryotes
The Early Atmosphere
• Gasses from volcanoes: N2, CO2, H2O,
H2, CO, probably ammonia (NH3) and
methane (CH4)
• No O2
• No ozone layer – intense radiation,
extreme temperature changes.
The First Living Things
• Anaerobic Organisms
• 1 billion years later, some
photosynthetic organisms began
releasing free oxygen.
How did those living things
come to be?
3 possible explanations:
1. Life originated on some other planet,
then traveled to Earth through space.
2. Life originated by unknown means on
Earth
3. Life evolved from nonliving substances
through interaction with their
environment.
2 of these cannot be tested, only one can
be stated as a hypothesis. Which one?
Chemical Evolution
Life evolved from nonliving substances
• Small, inorganic molecules were heated
via cosmic radiation, volcanoes,
radioactivity and lightning.
• Gasses in the atmosphere react,
forming organic compounds
• Compounds accumulate in oceans,
forming a hot soup
• Life evolved by chemical reactions and
transformations in the organic soup
Chemical Evolution
The oceans became “soup” of organic
compounds
The Heterotroph Hypothesis
The first living things were probably
heterotrophs that fed on organic
compounds in the ocean.
With no competition, autotrophs would
not have an advantage over
heterotrophs
The Heterotroph Hypothesis
(or Oparin-Haldane hypothesis)
3 Requirements
1. There had to be a supply of organic
molecules, produced by nonbiological
processes.
2. Some processes had to assemble
those small molecules into polymers
such as nucleic acids and proteins.
3. Other processes had to organize
the polymers into a system that
could replicate itself
Evidence for the Heterotroph
Hypothesis
Stanley Miller’s experiment in 1950. Early
Earth conditions were simulated in an
airtight apparatus.
• Water vapor
• Lightning
• CH4, NH3, H2O, H2
After circulating for a week, new
compounds were found in the water,
including some amino acids.
Other Sources of Organic
Molecules
•
Meteorites from space – amino acids
have been discovered
• Volcanic vents – release gases at
high temperatures
Remember 1st requirement: There had
to be a supply of organic molecules,
produced by nonbiological processes.
The rest of the hypothesis:
#2. Some processes had to assemble those small
molecules into polymers such as nucleic acids
and proteins.
Clay – repeating crystalline structure that could
attract then connect monomers
#3. Other processes had to organize the polymers
into a system that could replicate itself
RNA – Can form spontaneously. Can reproduce
itself. Probably came before DNA
Biological Evolution
• When did chemical evolution become biological
evolution?
• When organic molecules became living things
• Self reproduction, mutation that can be
inherited, and natural selection
• Cells? Today all living things are made of cells.
• It is unknown when/how cell membranes
developed.
• The first living things may have had membranes,
or not. They may have been DNA, RNA,
proteins…who knows?
Prokaryotic Fossils
3.5 Billion years old. Single-celled
prokaryotes.
Suggest life was already diverse and
thriving.
Probably methanogens
Fossils of Eukaryotes
• 2.1 Billion years old
• Lynn Margulis of UMass, Amherst
developed the endosymbiont hypothesis:
Chloroplasts and mitochondria were once
free-living prokaryotes. Photosynthesis
and respiration of the small cells have
benefited the host cells.
• Mitochondria probably evolved from
aerobic, heterotrophic purple bacteria.
• Plastids probably evolved from
autotrophic cyanobacteria.
Endosymbiont Hypothesis
The evidence: Both have their own DNA and
ribosomes, which are similar to other bacteria.
Also both have a double membrane; their outer
membranes may have evolved from vacuoles when
host cells took them in.
Quick Quiz
1. Why is it believed that methanogens
might have been the first
organisms?
2. How might mitochondria and plastids
have originated?
3. What evidence supports the idea
that mitochondria and plastids
originated from free-living
prokaryotes?
Chapter 18
Diversity and Variation
Outcomes
• Explain homology and give examples of
homologous structure
• Describe how the general characteristics
of the 5 kingdoms differ.
The 5 (or 6) Kingdoms
•
•
•
•
•
•
Archaebacteria
Eubacteria
Protista
Fungi
Plantae
Animalia
Bacteria/monera
Bacteria
• Prokaryotes
• First organisms to evolve
Protista
•
•
•
•
•
Earliest eukaryotes.
Usually single celled.
No organ systems
Nucleus developed
Mitochondria, flagellates, and plastids
became incorporated.
• Ex: amoeba, paramecium, algae
Fungi
•
•
•
•
Usually multicellular (except yeast)
Eukaryotic
Heterotrophs
Evolved from fungus-like protists
(slime molds)
• Ex: mushroom, mold, yeast
Plantae
• Multicellular, with complex body
systems (roots, stem, leaves)
• Autotrophs
• Eukaryotes
• Evolved from photosynthetic bacteria
• Ex: Flowering plants, Conifer, Mosses,
Ferns
Animalia
•
•
•
•
Multicellular with complex systems
Heterotrophic
Eukaryotic
Ex: Fish, Amphibian, Reptile, Bird,
Mammal
There are still lobe-finned fish today called
mudskippers. 34 species have been
identified. Unlike those we evolved from,
most of today’s species have only 2
appendages (front lobe-fins)
Fish to Amphibians
Reptiles to Birds
Evolution
of
Mammals
Eventually, some
mammals
returned to the
water.
• Today’s whales
had an ancestor
similar to a wolf.
Chapter 19
Changes in Species
Outcomes:
• Cite evidence from fossils, ecology, and
homologies that support the theory of
evolution
• Discuss the genetic and molecular
evidence for evolution
• Discuss isolation mechanisms that can
cause speciation
• Describe the patterns in evolution such as
punctuated equilibrium
1) When this fish dies, its body sinks to
the bottom where it is gradually
covered by mud (A).
2)
.
.
.
.
Its body starts to
decay (B), which is
caused by bacteria
metabolizing the
organic molecules
of the fish. If the
decay goes on long
enough there will
be nothing left of
the fish to be
fossilized. This is
one reason why
fossils are rare;
they decay before
being fossilized.
However, there are locations on the bottom of
the ocean with few bacteria. If a fish lands
on such a spot, and is quickly covered by mud
(C), it may not decay very much.
In the mud, the fish
body is turned into a
fossil by the
process of mineral
replacement.
Water slowly
carries away the
organic fish
molecules and
replaces them with
minerals (rock) until
only mineral
remains.
.
Like a book with pages of
stone.
Since the animals and plants are buried in sediments at the
same time that the sedimentary rock is forming, the fossils in
the rock layers must be the same age as the rock layers. By
using radioactive dating techniques, scientists can determine
the age of volcanic rock layers found between the sedimentary
layers and thus the age of the fossils too.
Soft-Tissue Fossils
Ice in the Arctic has preserved some
fossils for 1,000s of years.
In 1999 a wooly mammoth was
discovered intact.
Can it be revived by crossing with an
elephant? Different #s of
chromosomes (58 and 56), but 95%
similar DNA.
Scientists have found 250,000 species of
extinct orgnisms
Estimate that only 1 in 10,000 have been
found.
Evolution of the Horse
In these pictures, there
appears to be a straight
line progression from the
first horse ancetor to the
modern horse species.
Such a progression implies
an evolutionary goal, since
there is a trend toward
larger body size and fewer
toes.
Evolution of the Horse
However, evolution rarely
follows a straight line to a
goal.
Remember,
There are no goals in
evolution !
Evidence for Evolution:
Body Structures
1) homologous
2) vestigial
3) analogous
Homologous Structures: Traits that are
similar in different species because they share
a common ancestor.
Note how the bones have adapted to different niches
This is evidence of a common ancestor.
Vestigal Structures: No longer used.
The Human “Tailbone”
This is evidence that humans
evolved from an ancestor that
had a tail.
Vestigal Organ: human appendix
appendix
A whale has a
pelvic bone too,
and tiny leg
bones.
Analogous Structures: structures that
are similar in function but are not inherited
from a common ancestor.
NOTE: Analogous structures indicate that organisms
are not related.
Embryology is also used as Evidence of Evolution:
Similar development of the embryo is evidence of a
common ancestor
All three embryos have “gill pouches” in
the folds of the neck. All three have
tails.
As these embryos develop, note how the last two
continue to look similar. This indicates that they are
more closely related to each other than they are to
the first embryo
The last
two are
both
mammals!
This
suggests
that if
traced back
far enough
all three
have a
common
ancestor
because all
three have
similar
looking
embryos.
This is also
evidence of
evolution.
Perhaps the clearest
biochemical evidence
of the common origin
of living things is the
genetic code. The
same nitrogen bases
of adenine, thymine,
guanine, and cytosine
exist in every form of
life.
In addition, the genetic code itself –
the codons for the amino acids – is
almost universal.
The genetic code is the same in every known organism.
Every organism uses the same base codes for amino acids
Degree of Relatedness
Can be determined by
•
•
•
•
Amino acid sequence
Homologous proteins
Nucleotide sequence
Homologous genes.
More Genetic Evidence:
Pseudogenes
Gene duplication: produces multiple copies of
DNA sequences.
Pseudogenes: gene copies that don’t function,
so aren’t subject to natural selection.
Mutations occur unchecked.
According to natural selection, these noncoding sections should accumulate mutations
faster than functional genes – and they do!
Amino Acid Sequence
• Can be used to determine relatedness
How fast do
evolutionary changes
take place?
Based upon Darwin’s theory
it has long been believed
that evolutionary changes
were slow and gradual:
Gradualism.
1972: scientists Stephen
Jay Gould and Niles
Eldridge advanced a
different explanation about
the rate of evolution called
Punctuated Equilibrium
•Punctuated Equilibrium:
populations remain
genetically stable for
long periods of time,
interrupted by brief
periods of rapid change.
•sudden changes in the
environment
•increased mutation rate.
stasis
Speciation is the evolution of one
or more species from a single
common ancestor species.
Patterns of
Evolution
How do species remain
separate?
(1) Potential mates do not meet. Grizzly and Polar
bears.
(2) Potential mates meet but do not breed. Nocturnal
and diurnal birds. Leopard frog populations that
breed during different months.
(3) Potential mates meet and breed, but do not
produce viable offspring.
Divergent Evolution:
Occurs when isolated populations of a species evolve
independently.
Grizzly Bear
Polar Bear
Divergent evolution is responsible for
polar bears. A northern population
of grizzly bears became isolated
from others of the species and
adapted to the Arctic regions.
Coevolution:
Interactions with other
organisms effect
evolution.
Coevolution is responsible
for mimicry one of the
most fascinating topics in
biological evolution.
Coevolution
The pronuba moth and the
yucca flower
Depend on one
another for
reproduction.
Coevolution
The Orchid Fly
Coevolution: Cactus and
Galapagos Tortoise
Saddleback shell
Adaptive Radiation: Many diversely related species
from one common ancestor
Polyploidy in Plants
If plants inherit an extra chromosome from
parents, they are said to be polyploidy.
Often, these plants can only mate with other
polyploids, or use asexual reproduction.
Convergent Evolution:
Unrelated species display
similar features. No
common ancestor.
How does this happen?
Convergent Evolution
Similar niches usually contain similar
evolutionary pressures (selective
pressures).
If ancient niches were similar to modern
niches then organisms today could
resemble organisms now long extinct.
Similar niches found on different
continents can produce organisms that
are fairly similar.
Modern dolphins and prehistoric ichthyeosaurs
(marine reptiles) look very similar due to the
types of niche they inhabited.
Note how similar niches
created long necks in
both sauropods and
giraffes.
.
.
.
Quick Quiz
1. What are isolating mechanisms, how
do they operate?
2. What is polyploidy? What is its
connection to speciation?
3. Explain the statement: “Populations
evolve, not individuals within a
population.”
Origin of Species
Concept Review:
• New species can develop when populations
become separated and isolated.
• Similar traits can develop in unrelated
species occupying comparable niches.
• Interactions with other organisms affect
evolution.
• Many diverse species can evolve from one
ancestral species.
Chapter 20
Human Evolution
Outcomes:
• Describe how modern humans differ
from other primates
• Evaluate the techniques used to study
evolutionary relationships in humans
• Compare early hominids with Homo
erectus and Homo sapiens
• Give reasons for the difference in
the gene pools of modern human
populations.
What are Primates?
•
•
•
•
Opposable Thumbs
Fingers and toes have nails, not claws
Flexible shoulder and hip joints
Binocular, 3-D vision for accurate
depth perception
• Color vision
Humans vs. Other Primates
• Bipedal: Hands are free
• Have a hippocampus: brain region for
memory and learning. Absent in most
primates (not chimps and gorillas)
• More fine motor control in hands
• Language, well developed vocal chords
Molecular Similarities
Human vs. Chimpanzee
Protein
Number of amino acids Amino-acid difference
Hemoglobin
579
1
Myoglobin
153
1
Cytochrome C
104
0
Serum Albumin
580
7
Molecular Similarities Among
Primates
Species
compared
Difference in
DNA sequence
(%)
Chimpanzee vs. 0.7
Bonobo
Human vs.
1.6
Chimpanzee
Human vs.
2.3
Gorilla
Gorilla vs.
2.3
Chimpanzee
Estimated time
since
divergence
3 million years
7 million years
10 million years
10 million years
Early Hominids
• Lived in Africa
• Genera in Hominid family: Homo and
Australopithecus (larger teeth,
smaller brains).
The Hominids
Hominids – The Human-like
Primates
Comparing Skeletons
Skeletal fossils – clues to how organism
moves, eats, behaves.
Footprint fossils – How organism
moved, how heavy it was.
Who was Lucy?
Comparing Skeletons
Skeletal fossils – clues to how organism
moves, eats, behaves.
Footprint fossils – How organism
moved, how heavy it was.
Who was Lucy?
Australopithecus afarensis
found in Ethiopia, 1974
The First
Humans
Hominids