c. 1830: Lyell
(Rise of Evolution)
Lyell describes immense age of Earth. Most naturalists of the early
19th century think that the history of Earth -- and life on it -- spans vast ages.
Charles Lyell helps further this idea by arguing that slow-moving, gradual processes
explain Earth's geology. He echoes his mentor, James Hutton, who wrote that Earth's
history has "No vestige of a beginning. No prospect of an end." And Lyell becomes a
mentor himself to Charles Darwin. Darwin takes a copy of Lyell's Principles of
Geology on his Beagle voyage, and later will apply Lyell's notion of
gradual change to his theory of how species evolve.
1831-1836: Beagle Voyage
(Rise of Evolution)
Beagle voyage transforms Darwin. The voyage of the HMS
Beagle -- which carries Charles Darwin to tropical forests, Andean peaks, and
the Galapagos Islands -- is the most important experience of his life as a scientist.
When Darwin begins his voyage around the world, he intends to spend his life in the
clergy. But five years later, at the end of what was to be a two-year trip, he is a
changed man. He is now committed to a life discovering nature's laws. And the
collections he returns with -- particularly fossils from South America and creatures
from the Galapagos Islands -- become the basis of his budding ideas about evolution.
1837: Darwin's Secret
(Rise of Evolution)
Darwin starts secret notebooks. As experts sort through his
Beagle collections, Darwin feels compelled to pursue what he knows is a
radical -- even dangerous -- idea. His Galapagos birds, in particular, seem to
point out that new species can evolve over time from a common ancestor. Darwin
labels one of his secret notebooks "Transmutation of Species," and in it he sketches
his first "tree of life." It is a metaphor for how new species evolve.
1844: Anonymous
(Rise of Evolution)
Anonymous pamphlet on evolution strikes fury. Vestiges of
the Natural History of Creation becomes a notorious bestseller in England.
Author Robert Chambers, fearful of attack, publishes his evolutionary ideas
anonymously, and rightly so: scientists and clergy alike rally against it. One
of Darwin's former Cambridge teachers, the prominent geologist Reverend Adam Sedgwick,
leads the charge with an 85-page critical review. While secretly supporting its
premise, even Darwin agrees that the work is marred by faulty reasoning.
c. 1846: Lord Kelvin
(Evolution Challenged)
Lord Kelvin calculates the age of Earth. One of Britain's
most distinguished scientists proclaims that Earth is roughly 100 million years
old. William Thomson, later known as Lord Kelvin, arrives at this estimate by
assuming that Earth has cooled steadily since it first formed as a molten mass.
Kelvin later broadens his estimate to 20 to 400 million years old. His scientific
finding, unlike Bishop Ussher's 4004 B.C. date for the Creation, troubles Darwin.
Is 20 million years enough time for the diversity of life on Earth to evolve?
-> Go to 1850
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