Reading Darwin Between the Lines: A Computer- Assisted Analysis of the Concept of Evolution in The Origin of Species

Whereas Darwin is nowadays considered the
founder of the modern theory of evolution,
he wasn't the first to use this word in a
biological context: indeed, the word "evolution"
already had two distinct biological uses at the
time the
Origin of Species
was first published
(Bowler, 2003; Huxley, 1897): "initially, to
refer to the particular embryological theory of
preformationism; and later, to characterize the
general belief that species have descended from
one another over time" (Richards, 1998: 4).
Deriving from the Latin
evolutio
, which refers
to the scroll-like act of unfolding or unrolling,
the word «evolution» was first used in biology to
refer to the development of the embryo, mainly
through the formulation, promulgation, and
justification of preformationist and epigenetical
theories. Embryological evolution would receive
its fullest, most modern experimental and
theoretical account in the works of Karl
Ernst von Baer: characterizing embryological
development as a gradual differentiation
process leading from homogeneous matter to
the production of heterogeneity and complexity
of structure, von Baer would usually use the
word
Entwickelung
to refer to this dynamic
phenomenon, often followed by the Latin
evolutio
in parentheses. The ground-breaking
importance of von Baer’s work, as well
as its diffusion in the scientific community
through numerous translations, commentaries,
and appropriations, significantly contributed to
consecrate the embryological use of the word
"evolution".
As for the use of the word evolution to
describe specific development, its emergence
is closely tied to Lamarckism: even though
Lamarck never used the word ‘evolution’ himself
to refer to the transformation of species
over time and generations, his commentators,
detractors, readers and followers often did
however, thus contributing to the semantic
alteration of the term. Indeed, "by the 1830s,
the word "evolution" had shifted 180 degrees
from its original employment and was used
to refer indifferently to both embryological
and species progression" (Richards, 1992: 15):
Étienne Renaud Serres used the expression
théorie des evolutions
in his 1827 article
Théories des formations organiques
to refer
both "to the recapitulational
métamorphoses
of
organic parts in the individual and the parallel
changes one sees in moving (intellectually)
from one family of animals to another and
from one class to another" (Richards, 1992:
69); von Baer, in rejecting the possibility
of transmutation and the popular idea that
embryological development recapitulates the
progression of the species, used the word
«evolution» to refer to both processes; in
England, naturalists such as Charles Lyell,
Joseph Henry Green, Robert Grant and Richard
Owen also used the word "evolution" to both
comment and reject Lamarckism (Bowler, 2003;
Richards, 1993).
While this dual usage of the word and its most
common synonyms at the time (transformation,
development, transmutation...) has been
confirmed in the works of the most important
biologists and naturalists of the first half of the
19
th
century, little is known about Darwin’s own
stance on this matter: did he or not use the word
‘evolution’ or any other word to refer both to
embryological and specific development? This
question, however crucial it may appear, proves
very difficult to answer: while the
Origin of
Species
is generally considered as the birth
document of the theory of evolution, studies on
and around this book often overlook the fact
that the word itself is rarely used by Darwin, the

2
sole and slight exception being the sixth and last
edition (1872) of the work.
1
st
Edition (1)
evolved
: XV (490)
2
nd
Edition (1)
evolved
: XV (490)
3
rd
Edition (1)
evolved
: XV (525)
4
th
Edition (1)
evolved
: XV (577)
5
th
Edition (2)
evolved
: XV (573), XV (579)
6
th
Edition (14)
evolution
: (VII:201(2), 202), VIII (215),
X (282), XV (424 (3))
evolve
: VII (191)
evolved
: VII (191, 202(2)), XV (425, 429)
Occurrences of "evolution", "evolve",
and "evolved" in the Origin of Species
This lexical scarcity doesn’t necessarily mean
however that the concept of evolution isn’t
present elsewhere in the text, where the words
‘evolution’, ‘evolved’, and ‘evolve’ don’t appear.
According to distributional semantics theory,
meaning can be more easily stated as a property
of word combinations than of words
per se
: in
every sentence and paragraph, each word brings
its own constraints to the whole, reduces the sets
of possible words that could fit with it, therefore
increasing the total information conveyed and
structuring the semantic dimension of each
word thus combined. In short, this theory
holds that "similarities and patternings among
the co-occurrence likelihoods of various words
correlate with similarities and patternings in
their types of meaning" (Harris, 1991: 341). In
this sense, if concepts are thought of as networks
of such meaning-bearing word combinations,
then, conceptual structures can determine
the semantic dimension of a text without
being properly lexicalized; in other words,
such considerations, while emphasizing the
distinction between the semantic associations
of specific concepts and their embodiment
in natural language, also seem to imply the
possibility of "reading between the lines", that
is, of identifying and analyzing concepts on the
sole basis of their relations with other words
and concepts and independently of any proper
designation.
In view of this, the fact that the word "evolution"
itself is rarely found in the sixth edition of
the
Origin of Species
doesn't necessarily imply
that the lexical and inferential network it
refers to and that constitutes its conceptual
dimension isn’t present elsewhere in the text
and can't be studied in its stead. In this sense,
taking into account word combinations similar
to those where the word 'evolution' occurs
instead of focusing solely on the latter might
be the most reliable way to determine whether
or not Darwin’s concept of evolution in the
Origin of Species
refers to both embryological
and specific development, like most biological
theories of the same period. However, dealing
with word combinations manually might prove
difficult, if not impossible. In light of this, a
new computer-assisted conceptual analysis tool
has been developed by the LANCI laboratory,
one which aims to "read Darwin between the
lines", that is to identify where the author
"conceptually" refers to evolution, regardless of
the presence or the absence of the word itself.
Theoretically speaking, this new approach is
based on two fundamental assumptions: 1) The
inferential nature and dimension of a concept
are linguistically expressed in a differentiated,
contextualized and regularized manner; 2) these
regularities and patterns can be identified or
distinguished using algorithmic, iterative and
automatic clustering methods. Concretely, the
algorithm aims at "digging deeper into data"
by means of an iterative clustering process.
Following an initial clustering of the analyzed
corpus (in this case, the 974 paragraphs of
the sixth edition of the
Origin of Species
),
the iterative concordance clustering process
starts by retrieving the most characteristic
word of each cluster containing the word(s)
to be analyzed, that is, the word that has
the higest TF.IDF rating (Term Frequency –
Inverted Document Frequency) for each of
these clusters. Then, the concordance of each
of these characteristic words is extracted from
the corpus, and the same process of clustering,
cluster selection, TF.IDF rating and ranking,
word selection and concordance extraction is
performed on each of those new concordances,
until no new characteristic word is found or
no more clusters containing the word(s) to be
analyzed are found.
1. Concordance
extraction:
For each cluster containing the word(s) to
be analyzed, extract the concordance of the
highest-TF.IDF-ranked word.
2. Concordance
clustering:
For each previously unselected word, proceed
to the clustering of its concordance.
3. Iteration:
Return to step 1, unless 1) no new highest-
TF.IDF-ranked word is found, or 2) no
clusters containing the word(s) to be analyzed
are found.
Iterative Concordance Clustering Algorithm