26
N
atural selection, a concept
developed by British
naturalist Charles Darwin
and set out in his book On the
Origin of Species by Means of
Natural Selection (1859), is the
key mechanism of evolution in
organisms, resulting in different
survival rates and reproductive
abilities. Those organisms that have
higher breeding success pass on
their genes to more of the next
generation, so individuals with
these characteristics become
more common.To the Galapagos
The young Charles Darwin first
began to consider evolution during
his pioneering scientific expedition
around the world aboard HMS
Beagle from 1831 to 1836. As a young
man, Darwin accepted the orthodox
interpretation of the Bible, that Earth
was only a few thousand years old.
However, while he was on board
the Beagle, Darwin read Scottish
geologist Charles Lyell’s recently
published Principles of Geology, in
which Lyell demonstrated that rocks
bore traces of tiny, gradual, and
cumulative change over vast time
periods—millions, rather thanthousands of years. As Darwin
looked at landscapes around the
world that had been affected by
processes of erosion, deposition, and
volcanism, he began to speculate
about animal species changing over
very long time periods, and the
reasons for such changes. By
examining fossils and observing
living animals, Darwin identified
patterns; he noticed, for example,
that extinct species had often been
replaced by similar, but distinct,
modern ones.
Darwin’s field work on the
islands of the Galapagos archipelago
off South America in the fallEVOLUTION BY NATURAL SELECTION
IN CONTEXT
KEY FIGURE
Charles Darwin (1809 –82)BEFORE
1788 In France, Georges-Louis
Leclerc, Comte de Buffon,
completes his 36-volume
Histoire Naturelle, outlining
early ideas about evolution.1809 Jean-Baptiste Lamarck
proposes that creatures evolve
by inheriting acquired traits.AFTER
1869 Friedrich Miescher, a
Swiss doctor, discovers DNA,
although its genetic role is not
yet understood.1900 The laws of inheritance
based on the pea plant
experiments of Austrian
scientist Gregor Mendel in the
mid-1800s are rediscovered.1942 British biologist Julian
Huxley coins the term “modern
synthesis” for the mechanisms
thought to produce evolution.Charles Darwin Born in Shropshire, UK, in 1809,
Darwin was fascinated by natural
history from a young age. While
at Cambridge University, he
became friendly with several
influential naturalists, including
John Stevens Henslow. As a result,
Darwin was invited to join the
HMS Beagle expedition around the
world. Henslow helped Darwin
catalog and publicize his finds.
Darwin’s research brought him
fame and recognition—the Royal
Society’s Royal Medal in 1853,
nd fellowship of the Linnean
Society in 1854. In 1859, his book
On the Origin of Species sold outinstantly. Despite continuing
ill-health, Darwin fathered
10 children and never stopped
studying and developing new
theories. He died in 1882.Key works1839 Zoology of the Voyage
of HMS Beagle
1859 On the Origin of Species
by Means of Natural Selection
1868 The Variation of Animals
and Plants under Domestication
1872 The Expression of
Emotions in Man and AnimalsNatural selection is daily
and hourly scrutinizing,
throughout the world,
the slightest variations.
Charles DarwinUS_024-031_Evolution_by_Natural_Selection.indd 26 12/11/18 6:24 PM