1. It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us
There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
There were numerous editions of “Origins”, each with editorial changes to the previous editions. Interestingly, Darwin inserted “by the Creator” in the last sentence in all editions from the second on, perhaps to appease the religious criticism of his work. Darwin was not an atheist. Special creation at the beginning (or anywhere along the evolutionary history of organisms) is not denied by Darwin’s theory. It is just not necessary to explain the observations Darwin used nor the theories he proposed, and there is no verifiable data to scientifically support such events.
Web page from section on Darwin’s Diary discusses Darwin’s thoughts about religion vs. his theories. This is part of the excellent PBS website on the program series, Evolution (link on page 3 of this PPT)
Full Paragraph: It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.
Parts of last paragraph of Charles Darwin’s, “Origin of Species by Means of Natural Selection or the Preservation of Favored Races in the Struggle for Life” Sixth Edition, January 1872

2. 12 shirts 1 carpet bag 1 pair slippers 1 pair of light walking shoes 1 microscope (a single lens model by Bancks & Son, London) 1 geological compass 1 plain compass 2 pistols (with spare parts) 1 rifle (with spare parts) 1 telescope 1 pencil case 1 geological hammer 5 simisometers 3 mountain barometers 1 clinometer 1 camera obscura 1 hygrometer (belonged to FitzRoy) 1 taxidermy book 2-3 Spanish language books 14 other books, including Humboldt's "Personal Narrative" and Lyell's "Principles of Geology Vol. 1" 1 coin purse (Fanny Owen's gift) 1 pin with a lock of Sarah Owen's hair (Fanny's sister)
Voyage of the Beagle
Darwin was 22 when the voyage began

3. © AboutDarwin.com (good link)
Voyage of the Beagle
The colored diagrams are from AboutDarwin.com, an excellent site, if you want to learn more about the voyage and all Darwin’s side excursions, copiously illustrated with maps, choose the voyage button -
© AboutDarwin.com (good link)

4. Fig 22.5 Voyage of the Beagle 1831-1836

5. Home again
Worked for 30 years, much of it here
Down House, in Downe, Kentshire, England, south of London. Darwin’s home from 1842 to 1882
Sand Walk, site of much of Darwin’s contemplation

6. Alfred Wallace British naturalist
letter from West Indies with article to review for Darwin to forward to geologist, Lyell
Proposed theory of evolution identical to the one Darwin was working on
Alfred Wallace ( )

7. Darwin Publishes
“Origin of Species” presented later in 1858 (32 years after then end of his voyage) and published 1st in 1859
Both men jointly presented their ideas to the London Philospophical Society

8. The Origin of Species
Evolution is the explanation for life’s unity and diversity
Natural selection is the mechanism
What evidence did Darwin draw on?
We’ll first look at the 3 inferences, then the evidence (observations) Darwin used to support it
See shaded table, p. 435 and following pages

9. Reproductive potential
Species have great potential powers of reproduction
Populations would increase exponentially if all individuals survived and reproduced

10. Populations are stable
But populations tend to remain stable over time
Except for seasonal fluctuations
Moose population on island in Lake Superior

11. Limited resources Environmental resources are limited
Discussion in Malthus, “Essay on the Principle of Population” helped clarify this
Lucky Lynx and its 1 hare

12. Observation 4
Individuals in a population vary extensively

13. Variation is inherited
Much of this variation is heritable
However, Darwin did not know the mechanism

14. Adaptation Organisms are adapted to their environments
A floral mantid on a flower. Please look at the entire figure in the text

15. Artificial selection Of plants and animals by humans
There are many other kinds of supporting evidence, some that Darwin was aware of, some not, that support the Theory of Natural Selection
Darwin kept and bred show pigeons and was well aware of the human-selected traits in dogs and agriculturally important mammals.
Vegetables selected by humans from wild “kole”
Of plants and animals by humans

16. Other evidence Homologous structures Forearm bones in mammals
Homologous structures are related evolutionarily, they may have the same function or not.
Recall that analogous structures are not related evolutionarily but share the same function.
Forearm bones in mammals

17. Biogeography
Present day distribution of marsupials relates to what we know about locations of continents during continental drift
Adaptive radiation of Australian marsupials compared to similarities among other mammals

18. Fossils
Fossil Trilobites
Elephant evolution based on fossils

19. Charles Darwin’s Legacy (a selection of his writing)
Journal of Researches into the Natural History and Geology of the countries visited during the voyage round the world of H.M.S. Beagle
On the origin of species by means of natural selection
On the various contrivances by which British and foreign orchids are fertilised
The variation of animals and plants under domestication
The descent of man and selection in relation to sex
The expression of the emotions in man and animals
The effects of cross and self fertilisation in the vegetable kingdom
The formation of vegetable mould, through the action of worms
John van Wyhe’s web site with links to
web copies of all of Charles Darwin’s writings

20. Darwins mechanism Natural selection Four conditions
Populations of species vary in their characters
Some of the aspects governing the characters are heritable
More offspring produced than can be supported by resources
Those best able to “cope” (= reach reproductive age) leave the most offspring

21. Darwin’s mechanism Net result – “survival of the fittest”
best adaptive characteristics survive
least adaptive “perish”
in next generation populations of the species
What is needed?
populations (individuals don’t evolve)
environments
time – lots of time