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The life of Charles Darwin and the story about his theory
} Born on Feb. 12, 1809 (204)
} Born into a wealthy family and was 5th of 6 siblings.
} Father was a doctor and financier, mother was a Wedgewood, which was the owners of the famous Wedgewood Dynasty makers of Fine China
} Grandfather, Erasmus Darwin, had proposed that all life came from a single organism, “the Great First Cause”
Ø Went to the University of Edinburgh Medical School, but dropped out after his second year as he did not enjoy, and couldn’t stomach the stressful surgeries which were done without anesthetics.
Ø He was then sent to the University of Cambridge to “make himself a respectable being” and become an “Anglican parson” Ø He began to enjoy his courses and in particular Natural Theology as he always had a love for nature.
Ø He began to work closely with his Instructor and eventual mentor Professor John Henslow.
} December 27, 1831, he joins the HMS Beagle as a naturalist on a five year voyage
} The ship’s mission was to map the coast of South America for Britain
} As a naturalist, Darwin was to observe and collect specimens
} In Argentina, Darwin uncovered fossils of the Megatherium and Glyptodon
} These fossils looked like giant sloths and armadillos
} The fossils were found in the same geological range as these modern animals
} Fossils of marine organisms also found in the Andes Mountains
} Island chain 1000 km west of Ecuador
} Discovered many new species with many similarities to species found on South America
} No native amphibians or large land mammals ◦ why?
} Marine Iguana: ◦ Closely
resembles iguanas from the South American Mainland
◦ Is the only known lizard able to dive and forage in water
} Giant land tortoises ◦ At least five unique
species were found on different islands
◦ Shells range from domed to “saddleback”
◦ Necks differ in length
} Darwin at first thought they were one species with variation
} 13 species with distinct characteristics
} Their beaks show variation in shape and size ◦ Why?
} Biogeography: The study of the geographic distribution of organisms based on living species and fossils
} The Galapagos Islands had many species found nowhere else on Earth
} This is often true of remote islands, such as New Zealand and Hawaii
Observations from the Galapagos Islands
Darwin’s Hypotheses Regarding Remote Islands
Many species of plants, birds, insects, and, in some cases, reptiles
Only these kinds of organisms are able to reach remote islands by crossing large expanses of open ocean
No native amphibians and very few land mammals
Amphibians and most mammals are unable to cross open ocean and will not be found on remote islands
Many unique species found nowhere else on earth
Over time, ancestral species have evolved into geographically isolated species
Unique species most closely resemble species on the nearest continental land mass
Unique species are descendants of ancestral species from the nearest continental land masses and will exhibit some similarities
} After leaving the Beagle in 1836, Darwin spent more than 20 years gathering evidence on evolution
} He knew that his theories would be controversial
} By the time he presented his theory, Darwin was able to not only explain that evolution had happened, but also how it occurred
} By 1844 Darwin had prepared an essay on his theory of Evolution, but did not publish it
} 1858 - received a letter from Alfred Russell Wallace, who had also concluded that evolution must be true
} This pressure led Darwin to publish his theory as On the Origin of Species in 1859
} Pg 320 in the textbook
} Chapter 7 Review Questions #34, 35, 36, 54
