Chapter 22
-------The first convincing case of evolution was published by
Charles Darwin.
Evolution – The transformation of the lifeforms on earth over
time
- Descent with modification
- Not a linear process
What kind of change?
- A change in the frequency of the alleles of a population
- Mutation which favors one allele or another
- A mutation that creates a new allele that is favored
How much time?
- Several generations for the organism
- For bacteria => could be a day or two
- For humans => could be 200-300 years
---------Darwin’s ideas were opposed by western philosophy
- The most popular hypothesis for the origin of species was
creationism.
Creationism states that all species are created exactly
as they exist today.
- May be strictly Biblical or may involve continual creation.
--------Fossils and record of change
- The evidence of some of the organisms which have existed
on earth is preserved as fossils
- Fossils are preserved remnants or impressions of an
organism, or something related to an organism that lived in
the past
- A succession of organisms is seen in the fossil record
- The differences between fossils and living species are great
, - New species appeared and others became extinct
However, these results were not used to support evolution
A French anatomist (Cuvier) founded the science of paleontology,
the study of fossils in the late 1700s and early 1800s.
Cuvier explained the layers of different species were caused by
separate catastrophic events.
The philosophy is known as catastrophism.
Catastrophism is a theory that states that the major
changes in the earth's crust are the result of
catastrophic events rather than a gradual process of
change.
Geological gradualism: the predecessor of evolution.
In the late 1700s, a geologist named Hutton proposed that the
large changes seen in the fossil records were the result of
uniformitarianism.
Uniformitarianism is the principle that profound
change is the cumulative product of slow, continuous
processes.
This was the first indication that the changes seen on Earth were
usually slow.
If the changes were slow, then the theological timeline of 6000
years must be in error.
- Eg. Grand Canyon had a river that ran through sedimentary
rock exposing different layers over extended periods.
Pre-Darwinian Theory of Evolution
Lamarck placed fossils In an evolutionary context.
,Lamarck compared modern species to the fossil record and
identified several lines of descent consisting of a succession of
older fossils => younger fossils => modern species.
In 1908, Lamarck’s comprehensive model was published.
Lamarck envisions many “ladders” of evolution that organisms
could “climb.”
The least complex organisms at the bottom of the ladders were
spontaneously generated.
The complexity of organisms increased in a “march toward
perfection” and the most complex organisms were at the top of
the ladder.
The mechanisms of change involved two principles:
1. Use and disuse – use it or lose it philosophy
2. Acquired traits can be passed along to the next generation
(extremely flawed, if we learn calculus then our offspring
wouldn’t need to learn.)
Charles Darwin (1809-1882) was born the year Lamarck published
his work on evolution.
He sailed on the voyage of the HMS Beagle (1831) He sailed all
across the world, having ample time to make observations and
think.
Charles Darwin
- Observed that South American organisms differed from
European forms
- Species of finches of the Galapagos islands were unique but
resembled species of South America
, Darwin's work was preceded in publication by the work of Wallace
whose work was in complete agreement with the hypotheses
championed by Darwin.
The work by Wallace prompted a hesitant Darwin to complete the
work he began years earlier.
Darwin's observations led to The Origin of Species published in
1859.
Darwin used a tree as a metaphor for the history of life.
- At each branch or fork, the species have a common ancestor
- Similar species have branched recently
- Species with greater differences branched long ago
- Most branches are dead ends
Natural selection and adaptation
Darwin’s book focused on natural selection in adaptation.
Darwin’s observations and their inferences:
Observation 1 – populations have the potential for exponential
growth
Observation 2 – population size is normally stable
Inference 1 – survival is a struggle, and only a fraction will survive
Observation 3 – traits are variable among individuals of a
population
Inference 2 – survival is not usually random, but is largely
dependent upon heritable traits
Survival of the fittest
Observation 4 – Most of those variable traits can be inherited
-------The first convincing case of evolution was published by
Charles Darwin.
Evolution – The transformation of the lifeforms on earth over
time
- Descent with modification
- Not a linear process
What kind of change?
- A change in the frequency of the alleles of a population
- Mutation which favors one allele or another
- A mutation that creates a new allele that is favored
How much time?
- Several generations for the organism
- For bacteria => could be a day or two
- For humans => could be 200-300 years
---------Darwin’s ideas were opposed by western philosophy
- The most popular hypothesis for the origin of species was
creationism.
Creationism states that all species are created exactly
as they exist today.
- May be strictly Biblical or may involve continual creation.
--------Fossils and record of change
- The evidence of some of the organisms which have existed
on earth is preserved as fossils
- Fossils are preserved remnants or impressions of an
organism, or something related to an organism that lived in
the past
- A succession of organisms is seen in the fossil record
- The differences between fossils and living species are great
, - New species appeared and others became extinct
However, these results were not used to support evolution
A French anatomist (Cuvier) founded the science of paleontology,
the study of fossils in the late 1700s and early 1800s.
Cuvier explained the layers of different species were caused by
separate catastrophic events.
The philosophy is known as catastrophism.
Catastrophism is a theory that states that the major
changes in the earth's crust are the result of
catastrophic events rather than a gradual process of
change.
Geological gradualism: the predecessor of evolution.
In the late 1700s, a geologist named Hutton proposed that the
large changes seen in the fossil records were the result of
uniformitarianism.
Uniformitarianism is the principle that profound
change is the cumulative product of slow, continuous
processes.
This was the first indication that the changes seen on Earth were
usually slow.
If the changes were slow, then the theological timeline of 6000
years must be in error.
- Eg. Grand Canyon had a river that ran through sedimentary
rock exposing different layers over extended periods.
Pre-Darwinian Theory of Evolution
Lamarck placed fossils In an evolutionary context.
,Lamarck compared modern species to the fossil record and
identified several lines of descent consisting of a succession of
older fossils => younger fossils => modern species.
In 1908, Lamarck’s comprehensive model was published.
Lamarck envisions many “ladders” of evolution that organisms
could “climb.”
The least complex organisms at the bottom of the ladders were
spontaneously generated.
The complexity of organisms increased in a “march toward
perfection” and the most complex organisms were at the top of
the ladder.
The mechanisms of change involved two principles:
1. Use and disuse – use it or lose it philosophy
2. Acquired traits can be passed along to the next generation
(extremely flawed, if we learn calculus then our offspring
wouldn’t need to learn.)
Charles Darwin (1809-1882) was born the year Lamarck published
his work on evolution.
He sailed on the voyage of the HMS Beagle (1831) He sailed all
across the world, having ample time to make observations and
think.
Charles Darwin
- Observed that South American organisms differed from
European forms
- Species of finches of the Galapagos islands were unique but
resembled species of South America
, Darwin's work was preceded in publication by the work of Wallace
whose work was in complete agreement with the hypotheses
championed by Darwin.
The work by Wallace prompted a hesitant Darwin to complete the
work he began years earlier.
Darwin's observations led to The Origin of Species published in
1859.
Darwin used a tree as a metaphor for the history of life.
- At each branch or fork, the species have a common ancestor
- Similar species have branched recently
- Species with greater differences branched long ago
- Most branches are dead ends
Natural selection and adaptation
Darwin’s book focused on natural selection in adaptation.
Darwin’s observations and their inferences:
Observation 1 – populations have the potential for exponential
growth
Observation 2 – population size is normally stable
Inference 1 – survival is a struggle, and only a fraction will survive
Observation 3 – traits are variable among individuals of a
population
Inference 2 – survival is not usually random, but is largely
dependent upon heritable traits
Survival of the fittest
Observation 4 – Most of those variable traits can be inherited
