The Variation of Animals and Plants HTML version

The Variation of Animals and Plants
Harriet Ritvo
Charles Darwin wrote On the Origin of Species in a hurry. He had, it was true, been
formulating his ideas and arguments for several decades—since his round-the-world
Beagle voyage of 1831-1836. These ideas and arguments had been slow to take definitive
shape; Darwin had nurtured and reworked them, amassing evidence for what he projected
to be a weighty magnum opus. Although he had shared his developing evolutionary
speculations with his closest professional colleagues, Darwin was reluctant to publish
them on several grounds. He was aware that his theory of evolution by natural selection
(or descent with modification) was complex, that it rested on vast but not incontrovertible
evidence, and that the chain of his reasoning was not uniformly strong. Further, his
conclusions challenged not only the scientific assumptions of many fellow specialists but
also the theological convictions of a much wider circle of fellow citizens.
In 1859, Darwin did not feel quite ready to expose his cherished theory to the harsh light
of public scrutiny. In the introduction to the Origin he confessed that although his work
on evolution by natural selection was "nearly finished," he would need "two or three
more years to complete it." The Origin was, he suggested, merely a stopgap, a schematic
"abstract" of a much longer and more fully supported treatise yet to come. He had been
moved to preview his labors in this way, he explained, because his health was "far from
strong" and, perhaps more importantly, because Alfred Russel Wallace, a younger
naturalist working in isolation in southeast Asia, had sent a paper to the Linnean Society
of London in which he "arrived at almost exactly the same general conclusions that I
have on the origin of species." If Darwin had not gone public with his theory at this point,
he would have risked losing credit for the work of many years.
As its reception showed immediately and has continued to show, the Origin benefited
from the succinctness imposed by circumstances. Darwin himself may have appreciated
this point; at any rate, he never produced the massive treatise, although he repeatedly
issued revised editions of the Origin. But he did not abandon his intention to buttress his
initial schematic presentation with additional evidence. In the course of the next two
decades he published several full-length elaborations of topics summarily discussed in
the Origin: The Variation of Animals and Plants under Domestication; The Descent of
Man, and Selection in Relation to Sex; and The Expression of the Emotions in Man and
Animals. In addition to fleshing out the Origin, these subsequent studies bolstered its
arguments and responded to questions raised by critical readers, especially pragmatic
questions about the way that descent with modification actually operated.