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What Best Explains Diversity?. I. Special Creation. II. Evolution. Aristotle to Darwin ~350 BC to 1800s. Darwin to Present. (A) Each organism originated independently. (B) Since the time of creation, each organism has remained the same. (C) All organisms were created recently. . - PowerPoint PPT Presentation
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I. Special CreationAristotle to Darwin~350 BC to 1800s
II. Evolution
(A) Each organism originated independently.
(B) Since the time of creation, each organismhas remained the same.
(C) All organisms were created recently.
(A) All organisms originated from common ancestors.
(B) Organisms have and continue to change over time.
(C) Evolution of organisms began 3.7 billion years ago
Darwin to Present
What Best Explains Diversity?
http://www.ucmp.berkeley.edu/history/evolution.html
For a more details concerning the History of Evolutionary Thought:
http://www.talkorigins.org/
For information about the Evolution/Creationist Controversy:
http://www.natcenscied.org/
National Center for Science Education:
The Important Players that Influenced Charles Darwin
John Ray (1628-1705) : Practiced “Natural Theology”; he thought that god’s creation can best be understood and appreciated through study of nature.
Carl Linnaeus (1707-1778): Father of taxonomy; authored Systeme Naturae. Also practiced natural theology.
Georges-Louis Leclerc, Comte de Buffon (1707-1788) : 1) Questioned the idea of Special Creation. Wrote about the similarity of man and apes in Historie Naturelle.2) Questioned the idea of a young earth in Les Epoques of Nature.
Erasmus Darwin (1731-1802): Great intellectual of 18th century
Organic life beneath the shoreless wavesWas born and nurs'd in ocean's pearly caves;First forms minute, unseen by spheric glass,Move on the mud, or pierce the watery mass;These, as successive generations bloom,New powers acquire and larger limbs assume;Whence countless groups of vegetation spring,And breathing realms of fin and feet and wing.
The Temple of Nature
William Paley (1743-1805): wrote: Natural Theology: or, Evidences of the Existence and Attributes of the Deity, Collected from the Appearances of Nature.
. . . when we come to inspect the watch, we perceive. . . that its several parts are framed and put together for a purpose, e.g. that they are so formed and adjusted as to produce motion, and that motion so regulated as to point out the hour of the day; that if the different parts had been differently shaped from what they are, or placed after any other manner or in any other order than that in which they are placed, either no motion at all would have been carried on in the machine, or none which would have answered the use that is now served by it. . . . the inference we think is inevitable, that the watch must have had a maker -- that there must have existed, at some time and at some place or other, an artificer or artificers who formed it for the purpose which we find it actually to answer, who comprehended its construction and designed its use.
Thought that only an Intelligent Designer could have made life.
Age of Comparative Anatomy
Georges Cuvier (1769-1832): Founded vertebrate paleontology and developed the comparative method of organismal biology. Established extinction as fact.
Geoffroy St. Hilaire (1772-1844): Geoffroy spent much time drawing up rules for deciding when structures in two different organisms were variants of the same type.
One of his more infamous theories was that the segmented external skeleton and jointed legs of insects were equivalent to the internal vertebrae and ribs ofvertebrates; insects literally live inside their own vertebrae and walk on their ribs. He is said to have stated, "There is, philosophically speaking, only a single animal."
Richard Owen (1804-1892): Defined homology in 1843 as "the same organ in different animals under every variety of form and function."
Jean-Baptiste de Lamarck (1744-1829)First Theory of Evolution
Humans
Pond Scum
ScaleOf
Nature
Time
Zooplankton
InsectsFish
MammalsAmphibians
Jellyfish
Transformational Evolution
Lamarck :
• Believed in inheritance of acquired characteristics (acquired during life)
Parents
ChangeInherited byOffspring
ParentsChangeDuring Lifetime
ParentsChangeDuring Lifetime
ChangeInherited byOffspring
ParentsChangeDuring Lifetime
Two SiblingGiraffe’s
Grows upAmong Tall
Trees:Longer neck
Grows upAmong Short
Trees
Inheritance of AcquiredCharacteristics
Importance of Lamarck’s Theory
• Recognized that life forms were connected
• Recognized that there is variation in traits
• Recognized that evolution requires time (Earth is Old).
• Recognized that inheritance is an important aspect of adaptation
Darwin (1809-1882)
• Two Major Ideas:– Common Descent All living and extinct species descended from one or a few
common ancestors.• aka: Macroevolution
– Adaptation occurs by Natural Selection The characteristics of organisms change through time as a
result of natural selection.• aka: Microevolution
“On the Origins by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle of Life”
The only figure in “On the Origins….”
Extinction
DifferencesAccumulateOver Time
Species 1 Species 2Species 1 Species 2 Species 3
Species 4 Species 5
Genus 1 Genus 2
Darwin’s Idea of Common Decent Implies:
(1) Branching evolution(2) That species accumulate differences over time
(i.e. Phylogeny = Genealogy of Species)
Systematists Study Differences Among Species to Reconstruct Phylogeny
http://phylogeny.arizona.edu/tree/
Evolution by Natural Selection
What is adaptation?
Process of genetic change whereby individuals of a
population become better suited to their environment
Evolution of developmental timing: metamorphosis vs paedomorphosis
Time
Metamorphosis
ephemeral pond
Hatching
Paedomorphosis
Adaptation to Permanent Pond
no metamorphosis
Evolution After Darwin
Most folks accepted idea of common descent, but not natural selection.
Competing theories were proposed:
Orthogenesis: variation in the characteristics of organismsis channeled in pre-determined directions.
Macromutation: downplayed the importance of continuousvariation and stressed discrete variation. Thought evolutiononly depended upon mutation rate.
The Modern Synthesis (1930’s - 40’s)
Synthesis of ideas/concepts among geneticists, natural historians, and evolutionary biologists that modern evolutionary biology is built upon.
Emphasized the co-action of random mutation, selection, genetic drift, and gene flow in microevolution.
Emphasized that these evolutionary processes were sufficientto account for macroevolutionary trends.