Download as to Man`s Place in Nature

Darwin’s Big Breakthrough:
Darwin and the Concept of Natural Selection
Galapagos Tortoise
(domed)
(saddlebacked)
Notes that tortoises on different islands have differently shaped shells
(perhaps from common ancestor but diverged in form due to geographic
isolation
Darwin’s Iguanas
Marine Iguana
Land Iguana
-The marine iguana is grey-coloured and eats seaweed whereas the
land iguana is brownish-coloured and eats land plants.
Both presumably arose from a common ancestor, but adapted to
different environments
Darwin’s Finches
seed crushers
biters
probers
Again, all of these are related and must have come from common
ancestor, but adapted to different conditions/needs.
Mechanism for Evolutionary Change ?
Seed of an idea planted by Thomas Malthus
“An Essay on the Principle of Population”
(concept of “struggle for existence”)
Populations must be kept in check by famine, war,
disease; otherwise they grow too large to be supported.
(there are winners and losers)
Charles Lyell
“Principles of Geology”
(uniformitarianism, deep time)
Tiny changes over a long period of time amount to large changes
Thomas Henry Huxley (“Darwin’s Bulldog”)
-British anatomist and physical anthopologist was one
of Darwin’s most fervent supporters
-promoted the concept of natural selection in his book
as to Man's Place in Nature (1863)
• Abstract on Natural Selection in 1842
• Marries Emma Wedgewood
• Receives essay by Alfred Russel Wallace on studies in Brazil
(similar conclusions as Darwin’s)
• Joint presentation by Darwin and Wallace
before Linnean Society
• On the Origin of Species published 1859
• Rebuttal before British Association for the
Advancement of Science in 1860
(Oxford Bishop Samuel Wilburforce opposes Darwin)
- Huxley supports Darwin
• The Descent of Man and Selection in Relation to Sex
published in1967
• Darwin dies in 1882
Principles of Natural Selection:
1. All living things vary
2. All living things tend to produce many offspring
3. Numbers of species tend to remain constant
Deductions:
1. There is a struggle for existence
2. In this struggle, only the fittest survive
Herbert Spencer (reporter) -- “survival of the fittest”
End of Lecture