(3) The theory: natural selection (pages 55-58)
(4) The tree of life (pages 59-65)
Reading Origin of Species – 2
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Category Archives: Ask the Beasts (1)
Reading Origin of Species – 3
Reading Origin of Species – 4
(7) Across space (pages 82-93)
By the 15th century, European explorers were accumulating more and more knowledge of the earth’s flora and fauna. As their discoveries increased, naturalists speculated that there might be important ‘centers of special creation’ around the globe. But in Origin Darwin argues that natural selection gives a more plausible explanation of the distribution of life.
Looking at the distribution of animals and plants around the globe, Darwin observes major patterns. These patterns cry out for explanation:
Reading Origin of Species – 5
(8) Mutual affinities (pages 93-95)
(9) “There is grandeur in this view of life” (pages 95-99)
Origin’s Chapter 14 probes the ‘mutual affinities of organic beings’ by focusing on various branches of biology (as practiced in Darwin’s day). Origin’s overarching argument is that the problems these disciplines were encountering could be addressed by his theory of descent with modification.
The discussion continues (1)
Notes from our discussion, February 5
From Carol McPhee:
Darwin’s books inspired light verse as well as serious reflections on the place of humans in the universe.
In the nineteenth century, Constance Naden, a brilliant student of science who had published several articles on materialism and evolution in the Journal of Science and Knowledge, had some fun with Darwin’s ideas on the female’s part in natural selection. Her poem “Natural Selection” is in the voice of a young geologist who attempts to woo his beloved with his fossil and rock collections. He loses her to a young man who can dance and sing better than he.
http://www.bartleby.com/293/389.html
The discussion continues (2)
Notes from our discussion, February 5 – from Rob Ross:
Molecular tree of life
Recent science has documented Darwin’s tree of life (Beasts, p. 59) in amazing detail. Here are four among the thousands of “tree of life” diagrams – created by scientists looking at differences in the amino acid sequence of proteins, or at differences in the nucleotide sequence of DNA.
Tree of all life
Click on the slide to enlarge it
The discussion continues (3)
“How does being a scientist affect your religious belief?”
At the end of Thursday’s discussion, Bob Pelfrey asked this question of John Horsley and Rob Ross.
Evolution of the Theory – 1
Some notes on the first half of Chapter 4, Evolution of the Theory…
The center holds
Darwin’s theory has held through many empirical testings, and today there is no reasonable scientific conflict about the theory. Scientists have noted key features that characterize evolution as a whole: kinship; novelty; cumulative body relationships – and a propensity, over time, to produce beings of ever more complicated structures by elaborating on simpler structures that already exist.
Misuse of the theory
But before long, Darwin’s theory became a resource for political and social causes, whose advocates tried to turn a biological theory into a script for human society. The fatal flaw lay in transferring a scientific theory about a biological process (that happens without conscious intent) to the arena of human interaction (where causes are intentional, willful, and complex.)
Evolution of the Theory – 2
Some notes on the last half of Chapter 4, Evolution of the Theory…
A cosmic lens
Does the ‘stuff of the world’ have an innate creativity? (see Beasts, p. 117)
The current consensus is that the universe originated about 13.7 billion years ago, in the ‘Big Bang’. Looking at biological evolution through the lens of cosmic evolution makes life’s propensity for novelty more comprehensible. Even in the early phase, the rate of cosmic expansion was calibrated ‘just right’: the proper rate of expansion created the right conditions for galaxies with all their different bodies to form.
We do not know exactly how life originated, but an extraordinary degree of ‘fine tuning’ in the cosmos’ basic structures, laws and properties of matter-energy set up the conditions for life as we know it to begin. Placing the origin of species within the larger framework of the history of the universe casts an illuminating light on life on earth in several specific ways:
What Darwin Didn’t Know
When we discuss chapter 4 this week, ‘Evolution of the Theory’, we’ll see some examples of scientific discoveries after Darwin’s time.