is It 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.
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
Voyage of the Beagle
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
AboutDarwin.com (good link)
Fig 22.5 Voyage of the Beagle 18311836
Home again
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
Alfred Wallace
British naturalist 1858 - 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
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
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?
Reproductive potential
have
Species great potential powers of reproduction Populations would increase exponentially if all individuals survived and reproduced
Populations are stable
But populations tend to remain stable over time Except for seasonal fluctuations
Moose population on island in Lake Superior
Limited resources
Environmental resources are limited Discussion in Malthus, "Essay on the Principle of Population" helped clarify this
Lucky Lynx and its 1 hare
Observation 4
Individuals in a population vary extensively
Variation is inherited
Much of this variation is heritable However, Darwin did not know the mechanism
Adaptation
Organisms are adapted to their environments
A floral mantid on a flower. Please look at the entire figure in the text
Artificial selection
Of plants and animals by humans
Vegetables selected by humans from wild "kole"
Other evidence
Homologous structures
Forearm bones in mammals
Biogeography
Adaptive radiation of Australian marsupials compared to similarities among other mammals
Fossils
Fossil Trilobites
Elephant evolution based on fossils
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
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
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