Darwinism meaning evolution

He used the phrase to describe one way to visualize all living creatures today on earth as the descendents of an original pair of parents.

Survivors today or in the future are like new buds on the old branches of a tree, the trunk and limbs of which are hidden from our view. These limbs are hidden by time and our limited sensory experience. But we can imaginatively visualize how apes, primates, chimpanzees or elephants are all just different branches on the family tree of vertebrates. By extension plants, animals and fungus are all branches on the same family tree of bacteria, who first brought forth life on this planet and --due to their metabolism-- sustain life today.

On the Origin of Species, notes.

Last of five theories put forth by Darwin is natural selection

pp. 36-37.

1. dynamic world "evolution"
2. common descent
3. multiplication of species -- adaptive radiation (finches, tortoises,pines)
4. gradualism
5. natural selection -- abundant genetic variation every generation; limited survival

"mechanism of adaptive change"
harmony and adaptability of the organic world

68.

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Is evolution by means of natural selection "an essentially mechanical explanation." ?

One step vs. two-step process: first, all creatures have a rather huge to incredibly prolific reproductive capacities; this creates variability. Second, not all offspring can possibly thrive equally well, due to:

rivals

scarcity

intelligence

courtship rituals

adaptive behavior

competition from other species (inter specific)

fortune

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Darwin's idea modern biological synthesis:
individuals convey variation +
reproductive success + selection from among the survivors of an abundant number of different offspring. Hence, not all variants are "hardy" in that they reproduce.

69.

Analog to animal and plant breeders is:

artificial selection to natural selection
humans select to humans do not select

"breeding pairs" are selected vs. differential survival

There is no definitive answer to whether or not Darwin was externally influenced by his times (zeitgeist) and what he read, or was he influenced internally by his method of evaluating evidence he collected by contrasting and comparing his findings with practitioners and writers.

69.

After 1833-36 voyage he was, with some help of ornithologist John Gould in 1837, a determined "evolutionist" .... What this meant was he had altered the status of human beings in the worldview of creation, natural history and biological thought.

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July, 1837, in Darwin's worldview nature and human order were altered:

"Yet, the causes of evolution were a complete mystery to him."

70.

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Aristotle had argued there were four causes:

1. Material forces or a dialectic account for changes we see.
2. Proximate the immediate reason something happens
3. Underlying belief that surface features are misleading
4. Teleological theory of purposefulness or the idea of an end cause

For the sake of reason, rhetoric, argumentation and proof, Aristotle is largely correct as far as the western approach to cause and effect is concerned.

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Consider how we today might define the four causes:

material -- genes from 23 female and 23 male chromosomes combine to form a human embryo
proximate -- fertilization occurs when an egg is "compromised" by a sperm cell: fertilization
underlying -- there are more offspring than there are opportunities for their successful survival All of the above steps are actually rational equivalent explanations from an Aristotelian view.

Teleological becomes a different story.

1. Mayr argues Darwin is not teleological, (doctrine of end causes), but is this what other's say?
2. Consider egg + sperm = fertilized cell or ZYGOTE, then blastula, gastrula, embryo, fetus, birth.

go back to four causes:

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Dominant Animal, Chapter One.

Vocabulary

natural selection -- the refutable law of variability and differential survival that has passed the test of experience over time and is hence irrefutable today concerning inheritable (hard inheritance) qualities in organisms that accounts for a differential rate of survival among offspring of the same generation who, for whatever reason, do not reproduce .

molecular -- compounds of atoms usually bound together by hydrogen, carbon and sulfur.

acquired traits -- characteristics that organisms learn from mimicry or culture that are hence "obtained" and are not genetically transferred.

inheritance of acquired traits -- soft inheritance -- Lamarckism (coined the term "biosphere") believed in the ability of creatures to pass on traits.

mitosis genes -- metaphor -- stands for all the inherited material passed from parents to offspring

chromosomes -- literally dark stained bodies -- places in cells where DNA is packed together.

asexual -- creatures (bacteria, yeast) that reproduce without resorting to fertilization.

sexual -- organisms that exchange genetic material by recombination to have offspring.
DNA - deoxyribonucleic acid, material of inheritance that has code to make proteins.

Literally the molecule that defines the genotype.

RNA - ribonucleic acid, plays many roles but one is to replicate the DNA code in cells.

Mitochondria -- organelles in eukaryotic cells that acquire their own DNA from female line -- power houses of the cell where ATP is burned to form ADP for energy.
ribosomes -- organelles in eukaryotic cells where RNA and enzymes rearrange proteins.

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Mayr's argument:

1. Darwin is inconsistent, largely because he had no awareness of Mendel's work on peas.

2.The theory attributed to Darwin of evolution was:

a. Neither original with Darwin

b. Nor the whole story, since there are five theoretical pieces to Darwin's ideas about biology.

3. Darwin and Wallace saw in the diversity of life a common elemental unity at work, such as the separation of species along Wallace's line shown here:

Wallace's line in Indonesia
4. Darwin's power lies in not any one of the five insights, but in how he placed them together to powerfully reveal -- in a causal explanation -- the mechanism beneath life.

Homework:
List Mayr's five parts of Darwin's beliefs:

The five parts of Darwinian evolution.

term;

meaning,

with an example:

Compare your response to two other peoples' when you come to class:

Change partners and compare again.

Goal is to list all five without resorting to the book, you may use your notes!

What is meant by, and what is wrong with each set of concepts empirically speaking?

fixity of the species, or the unchanging quality of species (special creation)?

Balance of nature?

Now look at Darwinism as a "worldview."

pp. 101-104.

Darwinism as the revolution in science Discuss the importance of Darwin's vision of life. Second half of Mayr's book: Darwinian Synthesis.

Answers to Questions on Mayr

On the Origin of Species, "A Facsimile of the First Edition" with an introduction by Ernst Mayr. 1964.

What Evolution Is, by Ernst Mayr. 2002.

Population thinking explained by Mayr as a cause for variation seen in nature.

Two unknown precursors of Darwin
1810-1859.

Patrick Matthew
1/1/1831
"There is a law universal in nature, tending to render every reproductive being the best possibly suited to its condition that it kind, or that organized matter, is susceptible of, which appears intended to model the physical and mental powers, to their highest perfection...."

Darwin acknowledges "he had anticipated by many years the explanation which I have offered of the origin of species, under the name of natural selection,..."

Edward Blyth
1810-1873
"May not, then, a large proportion of what are considered species have descended from a common parentage?"

Blyth was a "stepping stone" since he thought natural selection would create a continuity or stasis of traits that otherwise conserve species not actually promoting a gradual change within the species.

Bases his conclusion on Loren Eisley*, who "has given Blyth greater credit for contributing to Darwin's views..." p. 131

"could natural law, which Darwin claimed natural selection to be, rest on variations that occurred by chance?"

Ronald W. Clark, The Survival of Charles Darwin, ( N. Y.: Random House, 1984 ), pp. 128-131.

* anthropologist and author of Charles Darwin & the Mysterious Mr. 'X'.