1859
Darwin elaborates on his
theories of evolution in On the
Origin of Species by Means
of Natural Selection, which
is an instant sellout.Although the idea of evolution
became widely accepted, the
mechanism that made natural
selection possible was not yet
known. In 1866, an Austrian monk
called Gregor Mendel made a huge
contribution to genetics when he
published his findings on heredity
in pea plants. Mendel described
how dominant and recessive traits
pass from one generation to the
next, by means of invisible “factors”
that we now call genes.
The rediscovery of Mendel’s
work in 1900 initially sparked sharp
debate between his supporters and
many Darwinians. At the time,
evolution was believed to be based
on the selection of small, blending
variations, but Mendel’s variations
clearly did not blend. Three decades
later, geneticist Ronald Fisher and
others argued that the two schoolsof thought were complementary,
rather than contradictory. In 1942,
Julian Huxley articulated the
synthesis between Mendel’s
genetics and Darwin’s theory
of natural selection in his book
Evolution: The Modern Synthesis.The double helix
Advances in technology such as
X-ray crystallography led to more
discoveries in the 1940s and ’50s,
and the foundation of the new
discipline of molecular biology.
In 1944, chemist Oswald Avery
identified deoxyribonucleic acid
(DNA) as the agent for heredity.
Rosalind Franklin and Raymond
Gosling photographed strands of the
DNA molecule in 1952, and James
Watson and Francis Crick confirmed
its double helix structure the
following year. Crick then showedthat genetic information is “written”
on DNA molecules. The errors that
occur when DNA copies itself create
mutations—the raw materials for
evolution. By the 1980s it was
possible to map and manipulate the
genes of individuals and species. In
the 1990s, the mapping the human
genome paved the way for medical
research into gene therapy.
Ecologists also want to establish
whether genes influence behavior.
Back in 1964, William D. Hamilton
popularized the concept of genetic
relatedness (“kin selection”) to
explain altruistic behavior in
animals. In The Selfish Gene (1976),
Richard Dawkins further advanced
the gene-centered approach. It is
clear that aspects of evolutionary
biology will still spark debate as
long as ecologists continue to
develop Darwin’s theory. ■THE STORY OF EVOLUTION
1866
Gregor Mendel’s paper
“Experiments with Plant Hybrids”
outlines findings from his pea
plant experiments, laying
the foundations for the
field of genetics.1976
The Selfish Gene by
evolutionary biologist Richard
Dawkins offers a new
perspective on evolution,
looking at the gene, as opposed
to the species or group.1953
In The Eagle pub in
Cambridge, UK, Crick and
Watson announce that
they have discovered
the structure of DNA.2003
The Human Genome
Project produces the first
genetic blueprint of
Homo sapiens.19
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