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.

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.

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

12 shirts1 carpet bag1 pair slippers1 pair of light walking shoes1 microscope (a single lens model by Bancks & Son, London)1 geological compass1 plain compass2 pistols (with spare parts)1 rifle (with spare parts)1 telescope1 pencil case1 geological hammer5 simisometers3 mountain barometers1 clinometer1 camera obscura1 hygrometer (belonged to FitzRoy)1 taxidermy book2-3 Spanish language books14 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 Voyage of the Beaglethe Beagle

© AboutDarwin.com (good link)

Voyage of Voyage of the Beaglethe Beagle

Fig 22.5 Fig 22.5 Voyage of the Voyage of the Beagle 1831-Beagle 1831-

18361836

Home againHome again

Sand Walk, site of much of Darwin’s contemplation

Down House, in Downe, Kentshire, England, south of London. Darwin’s home from 1842 to 1882

Alfred WallaceAlfred 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 PublishesDarwin 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 SpeciesThe 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 potentialReproductive potential

• Species have great potential powers of reproduction

• Populations would increase exponentially if all individuals survived and reproduced

Populations are stablePopulations are stable

• But populations tend to remain stable over time

• Except for seasonal fluctuations

Moose population on island in Lake Superior

Limited resourcesLimited resources

• Environmental resources are limited

• Discussion in Malthus, “Essay on the Principle of Population” helped clarify this

Lucky Lynx and its 1 hare

Observation 4Observation 4

• Individuals in a population vary extensively

Variation is inheritedVariation is inherited

• Much of this variation is heritable

• However, Darwin did not know the mechanism

AdaptationAdaptation

• Organisms are adapted to their environments

A floral mantid on a flower. Please look at the entire figure in the text

Artificial selectionArtificial selection

• Of plants and animals by humans

Vegetables selected by humans from wild “kole”

Other evidenceOther evidence

• Homologous structures

Forearm bones in mammals

BiogeographyBiogeography

Adaptive radiation of Australian marsupials compared to similarities among other mammals

FossilsFossils

Fossil Trilobites

Elephant evolution based on fossils

Charles Darwin’s LegacyCharles Darwin’s Legacy(a selection of his writing)(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 toweb copies of all of Charles Darwin’s writings

Darwins mechanismDarwins 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 mechanismDarwin’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