20 Michael Ruse
Obviously this theory leaves as much unexplained as it explained. Cell theory
was now being accepted universally, and Darwin only uneasily used this to under-
pin his hypothesis. (An earlier unpublished version made no mention of cells.) No
real attempt was made to explain how gemmules could switch their effects on and
off. Most crucially, no real discussion was given of how the gemmules would be
transported around the body and deposited in the sex cells. One would think it
would be the blood that would be the key fluid here, but when Darwin’s cousin
Francis Galton ran experiments shifting blood from one rabbit to another with
negative effects, Darwin responded rather huffily that he had never said it was
the blood that was important. Which may have been true, but which also leaves
the question of transport even more open. Not surprisingly, although Darwin ex-
pressed relief at having some hypothesis of any kind, generally it was not a great
success or much adopted by others. Although one might legitimately point out
that no one else had much idea about heredity. It required years of painstaking la-
bor with the microscope, working out the details of the cell, before answers started
to emerge at the beginning of the twentieth century.
The really major project that occupied Darwin in the years after theOrigin
was his work on our species,Homo sapiens. His study,The Descent of Man and
Selection with Respect to Sex, appeared in 1871, with a kind of follow-up volume,
The Expression of the Emotions in Man and in Animals, in 1872. I noted earlier
that Darwin, almost uniquely, never had any problems whatsoever in thinking of
our species from a natural perspective. Those Tierra del Fuegians had struck deep
into the heart of the Beagle’s naturalist. We are animals like the others. Indeed,
the very first jottings that we have in Darwin’s notebooks, showing that he had
grasped the idea of natural selection, deal with humans. And not just any aspect
of humans, but that which makes us special.
[November 27, 1838] An habitual action must some way affect the brain
in a manner which can be transmitted.— this is analogous to a black-
smith having children with strong arms.— The other principle of those
children. whichchance? produced with strong arms, outliving the
weaker ones, may be applicable to the formation of instincts, indepen-
dently of habits.— the limits of these two actions either on form or
brain very hard to define. [Barrettet al., 1987, N 42-43e]In theOrigin, Darwin was circumspect. He knew that the implications of his
theory for humans would be the major point of controversy. (He was right about
that!) So he wanted first to concentrate on getting the full details of his theory
out on the table, as it were. Hence he stayedaway from the human question in
theOrigin. But he did not want to conceal his opinions — no one was going to
say that Charles Darwin did not realize where it all led. Hence, one of the most
understated comments of all time: “Light will be thrown on the origin of man and
his history” (488).
The early 1860s saw a spate of books on the man question. Thomas Henry
Huxley jumped right in withMan’s Place in Nature [1863], with a frontispiece