24
The Theory of Evolution and Its Impact
The Theory of Evolution and Its Impact
.
Aldo FasoloEditor
The Theory of Evolutionand Its Impact
EditorAldo FasoloDipartimento di Biologia Animale e dell’UomoUniversita di TorinoVia Accademia Albertina 13I-10124 [email protected]
The publication of this book has been made possible by the financial support of the Acca-demia delle Scienze di Torino.
ISBN 978-88-470-1973-7 e-ISBN 978-88-470-1974-4DOI 10.1007/978-88-470-1974-4Springer Milan Dordrecht Heidelberg London New York
Library of Congress Control Number: 2011927742
# Springer-Verlag Italia 2012
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Contents
Introduction: The Sand Walk (on the Darwin’s Steps) . . . . . . . . . . . . . . . . . . . . . 1
Aldo Fasolo
Idola Tribus: Lamarck, Politics and Religion in the Early
Nineteenth Century . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Pietro Corsi
Darwinism Past and Present: Is It Past Its “Sell-by” Date? . . . . . . . . . . . . . . . 41
Michael Ruse
Evolutionary Theory and Philosophical Darwinism . . . . . . . . . . . . . . . . . . . . . . . . 53
Paolo Casini
Struggle for Existence: Selection, Retention and Extinctionof a Metaphor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Peter Weingart
The Theory of Evolution and Cultural Anthropology . . . . . . . . . . . . . . . . . . . . . 83
Henrika Kuklick
The Concept of Evolution in Linguistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Manfred Bierwisch
Theory of Evolution and Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Alberto Piazza
Genes, Evolution and the Development of the Embryo . . . . . . . . . . . . . . . . . . . 131
Giuseppina Barsacchi
v
Evolutionary Mechanisms and Neural Adaptation: Selective Versus
Constructive Strategies in the Development and Plasticity
of the Nervous System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Ferdinando Rossi
Is the Human Brain Unique? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Gerhard Roth
Aristotle and the Chicken: Animacy and the Origins of Beliefs . . . . . . . . . . 189
Giorgio Vallortigara
Evolution: Remarks on the History of a Concept
Adopted by Darwin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Volker Gerhardt
An Evolving Research Programme: The Structure of EvolutionaryTheory from a Lakatosian Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Telmo Pievani
.
vi Contents
An Evolving Research Programme:The Structure of Evolutionary Theoryfrom a Lakatosian Perspective
Telmo Pievani
Abstract The main topic of the paper is a discussion of the ways through which the
theory of evolution remakes itself, changes and grows, keeping alive and
reinforcing its Darwinian explanatory core. The theory shows a 150 years old
history of theoretical and empirical extensions and revisions, without any apparent
radical change of “paradigm” and without a rival Research Programme able to
replace it. The ongoing transition from the Modern Synthesis (MS) to a so-called
“Extended Evolutionary Synthesis” (ES) is here interpreted through the Methodol-
ogy of Scientific Research Programmes, proposed by the epistemologist Imre
Lakatos and updated. The current situation in evolutionary biology could be
represented by a “progressive” shift of the Darwinian research programme, moving
from the quite rigid theoretical framework of the standard version of Modern
Synthesis (gradualism, extrapolationism, adaptationism) to the more inclusive and
pluralistic “core” and “protective belt” of the Extended Synthesis. Promising and
advanced researches – like those concerning evolutionary developmental biology
(Evo-Devo), epigenetics, multiple ways of speciation and the role of structural
internal constraints – find in this perspective a realistic interpretation as theoretical
and empirical novelties with huge implications, nevertheless not incoherent with an
extended Neo-Darwinian explanatory core. A Neo-Lakatosian approach seems
useful when we discuss the extension of evolutionary models in non biological
fields, avoiding the application of just metaphorical forms of “ultra-Darwinism.”
This analysis in terms of a rational and continuous dynamics of growth of biological
thought seems much needed also for a critical examination of some popular and
radicalized controversies about the health of a no better defined “Darwinism or
Neo-Darwinism.”
T. Pievani (*)
Philosophy of Science, University of Milano-Bicocca, Milan, Italy
e-mail: [email protected]
A. Fasolo (ed.), The Theory of Evolution and Its Impact,
DOI 10.1007/978-88-470-1974-4_14,# Springer-Verlag Italia 2012
211
1 What Makes Biology Unique (and What It Does Not)
The elements of uniqueness and epistemological autonomy of evolutionary biology
(or, better, of the set of evolutionary fields), firstly outlined by Ernst Mayr [33],
could be updated today in the following lines:
• The apparent absence of universal “laws”, due to the abundance of descriptions
and singular existential assumptions;
• The historical nature of the explanations (narrative dimension, historical contin-
gency, the role of chance, unrepeatable events, irreversible processes);
• The diffusion of objects of study with features of uniqueness, ambiguity in
definitions, unlikely to be categorized and ascribed to an unambiguous set of
phenomena;
• The nested multiplicity of spatial-temporal levels of analysis and the stratified
hierarchy of non-reducible patterns of explanations (like in the case of emergent
properties between different levels of organization, or in the case of different
spatial and temporal focalizations between macroevolution and microevolution,
with the need to integrate non reducible patterns emerging at the nested levels of
genes, cells, organisms, populations, species, ecological systems and so on).
Nevertheless, it is interesting to observe that now three other elements of
“uniqueness” (in a negative sense, with respect to the epistemological status
of physical sciences used as a model) are no longer considered as crucial, because
of the ways through which the theory of evolution is able to deal with “evidences”
today [57]:
• The alleged impossibility of falsification of evolutionary hypotheses, avoided
thanks to the strongly convergent evidences coming from very heterogeneous
fields like paleontology, comparative anatomy, molecular biology, cladistics,
paleo-ecology and others; using such convergent proofs, the evolutionary
reconstructions could be compared and discussed in terms of parsimony (like
in the case of phylogenies) and explanatory power, selecting alternative models
case by case;
• The alleged absence of experimental methodologies based on the repeatability of
experiments and the modulation of parameters in laboratory (researchers can
simulate and experiment selective pressures acting on populations of
microorganisms, observing in laboratory dozen of thousands of generations
with their mutations and rates of genetic change; evolutionary developmental
biology and synthetic biology are pushing ahead the experimental status of
evolutionary researches, with the possibility of tuning the molecular parameters
of living beings, and in other fields like cognitive ethology and evolutionary
psychology it is time for an extensive use of comparative behavioral experiments
in different experimental situations);
• The alleged incapacity to produce genuine scientific predictions: this is not the
case anymore, when several evolutionary disciplines have predictive models
212 T. Pievani
testable both in ecological fields, and even now in the wild [23], and in labora-
tory with micro-evolutionary experiments.
The relatively recent adoption of “classical” experimental procedures cannot
justify, anyway, a reduction of the evolutionary biology to the epistemological status
of mathematical and physical sciences (status itself evolving). The “mimicry” with
physics is not realistic when we have to deal with historical, hierarchical and singular
processes. Not only past evolutionary events, but also current phenomena like
speciation, are unlikely to be observed and reproduced in laboratory. It seems more
convenient to outline a specific epistemological status for evolutionary researches –
different, and certainly not weaker than those of other disciplines – where reproduc-
ibility and classic experimental verifications represent a subset of the methodologies
that evolutionists should adopt, including the consilience of heterogeneous evidences
(like in the case of the “total evidence” approach to phylogenies), comparative proofs,
a multiplicity of coherent observations, historical reconstructions based on direct and
indirect evidences coming from several local disciplines. Only this articulated set of
methodologies seems able to manage such a complex and interdisciplinary empirical
basis. So,
• The modern theory of evolution explains a huge amount of single, verifiable
facts, in the past and present, and frames of verifiable facts;
• These facts are logically connected and produce coherent frames of corroborated
evidences;
• These connections of explained facts allow to formulate “risky” predictions and
retro-dictions, both verifiable or falsifiable with new facts, enlarging progres-
sively the empirical content of the theory through a process of criticism and
growth of knowledge.
What could we say about the structure of a scientific theory able to do that? The
elements of uniqueness, above described, usually expose the reconstructions of
the history of biological thought to quite appealing “radical” interpretations of the
ongoing theoretical changes, as if we had more “theories” of evolution or, even,
more alternative “languages” on the field. This is the case of the call for the concept
of “paradigm”, in Thomas Kuhn’s sense [28], in the description of the history of the
different stages of the theory of evolution after Darwin. According to Mayr [33],
paradigm is too strong a concept in order to understand the theoretical fluidity and
the heterogeneous basis of empirical facts that we find in natural history. Like
Massimo Pigliucci recently noted [53], there is nothing in the field at the moment
that could suggest the typical features of a “paradigm shift” between incommensu-
rable explanations and conceptual languages.
If we would say that the current theory of evolution is a “paradigm”, actually we
do not see the accumulation of serious anomalies and the dogmatic crystallization
that should precede a paradigmatic crisis. What is typical of the field is, on the
contrary, the fact that new problems and apparent exceptions can be resolved and
understood mainly through integrative explanations, different modulations of the
empirical domain of application of already established patterns of explanation, new
An Evolving Research Programme 213
calculations of the relative frequency of a pattern with respect to another. It means
that the dynamics of growth and evolution of the theory is based on processes of
theoretical extension and empirical enlargement of an elastic set of explanations
already consolidated but constantly needing adjustments and integrations [2].
Something completely different from a “revolutionary” overthrow.
Does it mean, conversely, that we are in the middle of a static and prolonged
period of “normal science”, with just marginal scientific puzzles to be solved? Not
properly. An articulated set of explanations that brings together heterogeneous
facts, absorbs new facts, updates its theoretical toolkit when it is healthy, or
accumulates anomalies and auxiliary hypotheses when it is sick and it plods
along the experimental novelties, was defined neither simply a “theory”, nor a
“paradigm”, but a “scientific research programme” by epistemologist Imre Lakatos
[29]. It means that the evolutionary explanation is submitted to continuous changes,
even very deep sometimes, and appears like an open and busy yard, not like an old,
traditional building. So, the theory of evolution is evolving, or better, the evolu-
tionary scientific programme is evolving. But how exactly? Along which lines?
What is under potential falsification here is not a single concept or the content of
a single theory, but a succession of theories and integrated models: in other words
the rational dynamics inside the process of updating and redefinition of a coherent
whole of explanations, included the strategies of defense against contrary evidences
and apparent contradictions [29, 37]. The process of criticism and growth of the
evolutionary knowledge after Darwin seems a continuous one – made by
extensions, revisions, and even reversions to originally Darwinian insights [9] –
and not a discontinuous, paradigmatic one. Without any underestimation of the
importance of external, social and psychological, factors in science, the pivotal
course of the conceptual change is an internal, logical one, depending on new
corroborated evidences and theoretical advancements.
2 How Many “Darwinisms”?
A flexible structure of the evolutionary scientific programme suits with the standard
pattern of the history of biological thought very well, intended as a succession of
stages of integration, revision and expansion. Synthetically:
• The originally Darwinian explanatory frame, structured with: (a) a wide descrip-
tive apparatus (evolution as a matter of fact, common descent with
modifications, the tree of life); (b) an integrated set of multiple explanatory
factors, such as individual and non-directed variations, natural and sexual
selection (the variation-selection core), and Lamarckian “residuals” (where
each concept has had afterwards a different fate – [31, 32]); (c) some meaningful
risky predictions and retro-dictions, with different fates as well (about the depth
of time, the pervasive gradualism, the hypotheses concerning the evolution of
complex structures, the role of geographic isolation); (d) a powerful cultural
214 T. Pievani
revolution, but technically not a paradigm shift, being rather a transition from
pre-scientific views like natural theology and the entry of the first general
scientific programme in evolutionary fields (adopting already circulating idea,
but in a new and wholly naturalistic explanatory frame).
• The original “Neo-Darwinism” (term coined by George J. Romanes, a pluralistic
Darwinian, interested in ethology and evolution of the animal minds, and used
also by scholars like Alfred R. Wallace and Asa Gray), at the end of the
nineteenth century reinforces the Darwinian core, removes the Lamarckian
residuals and establishes with August Weissman the bases for the conceptual
separation of hereditary biological materials and their bearers, giving to natural
selection a quite exclusive explanatory priority.
• The Evolutionary Modern Synthesis (MS) – preceded by a phase of eclipse of
Darwinism (according to JulianHuxley, 1942, and then [3]) during the re-naissance
and rediscovery of Mendelian genetics and the birth of macro-mutational and
saltationistic theories of biological change – could be represented as a kind of
powerful “Neo-Darwinism of second generation”, with the fusion of Mendelism
and population genetics, the first mathematical models for the changes in the
frequencies of genetic variants in populations, and a genetic theory of natural
selection; at that time, the convergence of two traditions of research created the
first global evolutionary scientific programme, with a strongly coherent theoretical
frame (the variation-selection core), a great expansion of predictive power, entire
new fields of evidences for the Darwinian core of the theory of evolution; at the
same time, the synthetic power ofMSwas reached through a crystallization around
few methodological assumptions (in some cases so strong and normative, espe-
cially in worldwide handbooks, that they seemed quite “paradigmatic”), like the
extrapolation of any macro-evolutionary phenomenon from micro-evolutionary
processes, gradualism and uniformitarism, a diffused adaptationism [20], the
underestimation of evidences (with exceptions in single authors – [35]) coming
from embryology, ecology and human evolution [16, 45].
• Since the sixties of twentieth century, we see a new rapid extension of the
empirical basis of evolution, together with technological advices, because of
the molecular revolution, the acceleration of genomics and post-genomics, the
new detailed phylogenies, the role of the evolutionary developmental biology
(Evo-Devo), the growth of epigenetics, and there is a general consensus about
the fact that we are in front of a “contemporary Neo-Darwinism”, the third
generation, quite different from the previous ones.
Disciplines less highlighted in MS, embryology and ecology, are acquiring their
deserved, lost centrality. But mostly, MS was subjected to deep theoretical
challenges, like neutralism, Punctuated Equilibria, and now Evo-Devo itself. The
assimilation of these challenges and the metabolism of such a huge amount of new
data were much slower and harder than any other passage in the past decades, and
claimed a profound change in the structure of the evolutionary scientific
programme. So what kind of “Neo-Darwinism” do we have today in the field? Do
we need a completely new Evolutionary Synthesis or will some superficial restyling
An Evolving Research Programme 215
be enough? Is the new structure of contemporary Neo-Darwinism already stabilized
or in a phase of transmutation? The Lakatosian methodology of the Scientific
Research Programmes (SRP) seems the right candidate in order to understand the
ongoing transition.
With respect to the alleged incompleteness of MS frequently addressed in
contemporary debates, it seems quite clear that MS showed a great capacity of
inclusion [2], through processes of theoretical assimilation that enlarged its empiri-
cal basis and prevented logical and explanatory objections. But, in a first phase, this
assimilation produced the need for a more pluralistic way to understand the
rhythms, the units and the levels of evolution.
In the case of Punctuated Equilibria theory [15], after decades of debates the
general consensus around the mechanisms of speciation is that we need a multiplic-
ity of processes and modes of birth of new species (punctuated in some ecological
circumstances and gradual in others), a multiplicity of possible rates of speciation,
and a multiplicity of levels of change (from an ecological and a genealogical point
of view) to be considered [8]. So the main methodological stance today is a
calculation of the relative frequencies of one pattern (punctuationism) with respect
to another (gradualism and trends) [44], and not a radical alternative between two
incompatible patterns.
What we see is precisely a balance between points of breaking of past methodo-
logical stances inside MS (like phyletic gradualism) and points of theoretical
continuity. In the case of Punctuated Equilibria, the points of breaking are:
punctuations are not due to imperfections of the geological record; speciation is
not only anagenetic, but frequently cladogenetic; speciation is connected with
major episodic evolutionary changes; the wide diffusion of apparent stasis in
natural histories. The points of continuity with MS are: the evolutionary
mechanisms in action during the speciation are Darwinian; gradual trends (plurality
of patterns) are not excluded; and mostly, punctuation and stasis stand at the level of
geological scale of species life, so they do not clash with normal mechanisms of
change at the level of populations of organisms [20].
A quite similar process of assimilation of new evidences with a consistent
internal theoretical accommodation is at the core of the history of another challenge
to MS: neutralism [26] and contemporary weak-neutralism. In the frame of a
renewed MS the evidence of a huge amount of variations and sequences inside
the genome with no adaptive and selective origin is accepted with the cost of a
robust quantitative and mathematical integration in the models. Neutralistic
patterns based on drifts and on structural internal mechanisms, non selective at
the level of organisms, show that natural selection is not the exclusive factor of
genomic change, but an important one among others. Like in the case
of punctuationism, we need a calculation case by case of the relative frequencies
of selective patterns and drift patterns when we look inside the structure of the
genome.
A quite different example is the challenge posed by the discovery of the
crucial role of macro-evolutionary patterns in evolution (like turnover pulses of
species, rapid adaptive radiations, mass-extinctions), because it breaks the strong
216 T. Pievani
methodological assumption that every macro-evolutionary phenomenon should be
extrapolated by the uniform accumulation of micro-evolutionary processes. The
integration needed seems more and more profound. Other recent fruitful fields of
researches threaten the capacity of inclusion of MS, because they touch fundamen-
tal ribs of the theoretical architecture of MS or in some cases add entire new
domains of experimental evidences that claim for a powerful theoretical updating:
• The discovery of families of genes and hierarchies of genes, with a still up to
now underestimated complexity of the genetic regulation, changes the idea itself
of the genome, the machinery of the mutations and the phenotypic effects, the
definition of the concept of “gene”; so, the “raw material” of any evolutionary
process is no longer so “raw”;
• Evo-Devo suggests a crucial role for the constraints to variation, for the internal
developmental constraints, for systems innovations, functional cooptations,
changes with a modular logics [5, 18, 34, 36];
• The field of epigenetics enlarges the range of the sources of variation and
inheritance [24];
• The phenotypic and developmental plasticity modifies the relationships between
genomes, phenotypes and ecological niches [51, 62];
• The “niche construction” hypothesis [40] is a new, constructivist, way to see the
active role of the organism in evolution and the reciprocal modifications of
organisms and niches; this idea fits with the Developmental Systems Theory
[42, 43];
• The concept of “evolvability” is evolving itself [27, 52];
• The generation of order and structural complexity through mechanisms of
biological self-organization is real and deserves attention [25].
For each of these lines of researches we need more data and a careful consideration
of the real theoretical impact.Anyway, the capacity of painless assimilation of scientific
novelties by MS seems to be progressively declining. The problem is no longer of
partial “incompleteness”, but the adequacy of the whole conceptual structure of the
theory [20]. Maybe we need a new kind of Neo-Darwinism, revised and extended.
Using themethodology of Lakatosian SRP, we argue here that the transition in progress
from the MS to the so called “Evolutionary Extended Synthesis” (ES) [55] could be
represented as a shift froma previous evolutionary research programme (ERP1), turned
to be “regressive”, and a new evolutionary research programme (ERP2), with an
extended Neo-Darwinian core and a protective belt of new assumptions and auxiliary
hypotheses with a pluralistic and integrative explanatory approach.
3 Core and Protective Belt of a Scientific Research Programme
According to Imre Lakatos, the growth of the scientific knowledge is a process quite
independent from the mind of a single scientist: the product of the discovery
becomes autonomous from the mental activity that created it, like a growing living
An Evolving Research Programme 217
organism with proper laws of development. So the history of science could have
internal rational reconstructions, with an acceptable degree of objectivity, a logical,
continuous, internal dynamics of change through criticisms, new assumptions,
extensions and revisions. As we have seen, the term “theory” appears inadequate
to depict the current state of the evolutionary programme of researches in different
fields and with several integrated patterns of explanations (better than separated
“concepts”, like in [32]). How does a corpus of explanations with these
characteristics evolve and transmute?
In Lakatos the continuity of the history of science is given by the transformations
of scientific research programmes, that are sets of models, concepts and hypotheses
delimited by the choices of a community of scientists: firstly, they establish a
complex of theoretical postulates and corroborated explanations which are no
more subjected, in the practice of research and publications, to falsification. This
operative and methodological choice gives birth to the “core” of the RP. Of course,
the core is un-falsifiable exclusively from a methodological point of view, not in
principle: the scientists decide (according to an “inductive conjectural principle”)
that a core of explanations is confidently corroborated and reliable, and go ahead.
The choice, in this “sophisticated fallibilism”, is pragmatic, provisional and risky,
and any rival RP has the duty to hit and weaken the core. The inductive reliability of
the core has two criteria: the additional empirical content (predictions of new facts);
the corroboration of the additional empirical content (the predictions indeed
increase the empirical content of the RP).
Though the corroboration will never be ultimate in science, the pragmatic
preference for theories scientifically healthy is rational because they are conjectur-
ally reliable. The core contains also the influent metaphysics of the RP, driving the
researches through the great iconographies and metaphors of the RP, the philosoph-
ical views, the initial assumptions. The core produces the heuristic rules that
indicate the ways to be taken (positive heuristic) and the ways to be avoided
(negative heuristic). These aspects of the core reveal a “kuhnian” mood and a
defensive tenacity, but the structure of the core can evolve continuously, depending
on the anomalies emerging and on the fight with rival RPs, nevertheless always
keeping its physiognomy and peculiarities. So the defensive tenacity is not dog-
matic and blind, but articulated in a continuous requalification of the core through
the heuristic.
The followers of a RP cannot insert everything in the core, because its formula-
tion should respect a historical criterion (a long process of “proofs and refutations”,
trials and errors – [30]) – that is, a series of successive, refutable models, able to
predict new facts – and a normative criterion, according to which the responsibility
of the choice is in charge with the scientists of the RP, and the success of the RP will
be evaluated by its empirical results. Then, with their creativity, scientists surround
the core with a “protective belt”, made by auxiliary hypotheses that protect the core
and nourish its evolution. The protective belt is made also by observational theories,
initial conditions, open problems, provisional hypotheses, other conjectures, and
must tolerate the external attacks by rival RPs thanks to continuous modifications,
adaptations, refutations and auxiliary hypotheses able to absorb anomalies and
218 T. Pievani
predict new facts. The crucial difference is that the protective belt is by definition
fallible, unceasingly mutable, and its specific contents are not vital for the survival
of the whole RP.
In its early phases, the protective belt is composed specifically [38, 39] by
assumptions of negligibility (neutralization of facts considered non essential for
the study of the phenomena explained by the RP), assumptions of domain (the
external application of the RP to other kinds of phenomena, keeping the RP under
control) and heuristic assumptions (defining the problems that the RP does not
intent to deal with, the anomalies considered non essential, the risky, provisional
ad-hoc hypotheses). If the heuristic is fruitful and acts on the protective belt
modifying the hypotheses in a way that powers the RP, if it makes it more realistic
with respect to new observations, and increases the empirical content of the set of
explanations, the whole RP is defined as “progressive”. If the RP loses empirical
content, accumulates anomalies and ad-hoc hypotheses, needs continuous
emendations, the heuristic is in crisis and the RP is defined as “regressive”. Such
a regressive RP will be sooner or later substituted by a rival RP, with a different
explanatory core, able to cover all the empirical content of the previous RP. The
ultimate refusal of a RP, like its initial foundation, is a free, operative, fallible
choice of the scientists. By principle, any attempt of extreme defense of a RP is
legitimate, as long as it respects the criteria of a critical rationalism and the
adherence to evidences, like a nucleus of standards of evaluation adopted by the
scientific community.
In front of an anomaly, the scientist pins the blame initially on a marginal part of
the protective belt (or on some initial conditions, parameters, auxiliary
assumptions), protecting the core as long as possible (like in the case of the
Darwinian ad-hoc hypothesis concerning the imperfection of the geological record,
in this way protecting the gradualist assumption involved in the core-mechanism of
natural selection). This defensive strategy could be successful: the anomaly is
solved, the heuristic is reliable, the empirical content grows. Or provisionally
successful: the patch apparently works, but it is weakening the protective belt. Or
clearly unsuccessful, showing a pseudo-scientific attachment to non refutable and
useless ad hoc hypotheses.
Avoiding both a strict and a-historical fallibilism and by the way any methodo-
logical anarchism or external subjectivism or radical change of paradigms, the
methodology of RP provides a possible rational criterion for understanding
the continuous growth of knowledge in a field of researches, in order to compare
the explanatory power of rival RPs, and evaluate the state of health of a long time
dominant RP as well. The shifts of RPs could be rationally evaluated: if the
modification of one or more auxiliary hypotheses – with the aim to restore
the matching between the core and reluctant empirical evidences – has turned out
to be a new version of the RP, supported by new facts, by an additional corroborated
empirical content and by more successful predictions, then the shift of the RP has
been “progressive” (that is, we have had a growth of knowledge).
On the contrary, if any modification of a previous version of the RP has only the
aim of “saving the phenomena” and generates a new theoretical system not
An Evolving Research Programme 219
supported by more independent evidences, then the shift is “regressive” and the RP
is facing a crisis. When a RP accumulates anomalies and is no longer able to
accommodate itself in a succession of models and theories that increase the
empirical content, the scientists should decide to abandon it and move to an
alternative frame, shifting the RS toward a new version (with a different theoretical
structure, even if compatible with the previous core) or choosing a rival RP already
available in the field. This decision is itself risky and subjected to falsification,
depending on the experimental results of the new RP.
4 The Progressive Shift Between MS (ERP1) and ES (ERP2)
What is the case of MS and ES in such dynamics? Using the methodology of RP, we
could say that:
• The core of the Evolutionary Modern Synthesis seems to have acquired today a
defined dimension, as long as we consider its boundaries not too much immuta-
ble and impervious to change [47, 49];
• There is no alternative approach able to catch the continuous dynamics of
change inside the evolutionary research programme, its meaning and its internal
debates;
• There is no evidence of a possible substitution of a dominant RP with a rival one,
with a radical refusal of a whole previous tradition of researches, but there is in
the field the typical scenario of a nonstop succession of shifts, extensions and
revisions of the contemporary Neo-Darwinian RP.
Furthermore, we know that MS has never been a monolith, but a meeting of
languages, disciplines and tradition of researches: at least the tradition of popula-
tion geneticists and that of naturalists, with respectively micro-evolutionary and
macro-evolutionary perspectives. Nevertheless, MS tended to crystallize its “con-
sensus” around some rigid methodological principles, intended as operationally no
more under falsification (as it is usual in any RP according to Lakatos), like phyletic
gradualism and genetic extrapolationism, defending a version of the RP based on a
gene-centered and pan-selectionist view [12]. The contemporary followers of this
ultra-Darwinian interpretation of the RP, with a great success in popularization,
have even more oversimplified the core in a rhetorical fashion, speaking about an
alleged universal Darwinian algorithm based on the “research and development”
activities of the supreme engineer, the natural selection. But it is interesting to note
the gap between this standard and popular view of evolution and the diversified
reality of the experimental field, monitored in the major International publications.
If we want a realistic epistemological representation of what is going on in the
field, we should recognize a “received view” of the RP, in these terms:
• The core of the RP named MS is the Neo-Darwinism as the genetic theory of
natural selection;
220 T. Pievani
• The protective belt is made by three major methodological postulates: phyletic
gradualism; extrapolationism from microevolution; and strict functionalism or
adaptationism; so we have a prevalence of assumptions of negligibility (strong in
the cases of embryology, ecology and paleontology) and heuristic assumptions
(like in the case of the underestimation of structural internal factors in
evolution);
• The deriving positive and negative heuristic is based on the programmatic idea
of a universal, basic Darwinian logics, able for decades to gather a huge amount
of new facts and prediction, with more and more sophisticated mathematical
models.
The MS so conceived shows also weak assumptions of domain in the belt (the
application of the theory is supposed to be large, and widely extra-biological): the
most important extensions of evolutionary models outside the strictly biological
territory come from the application of this oversimplified version of the RP (like in
the case of the strongly adaptationist approach in early evolutionary psychology –
[4, 11]). But the claims of extended applicability clash with the growing difficulty
to absorb in this standard frame the reluctant lines of researches above mentioned.
So, the structure of the forthcoming theory of evolution could be represented as a
profound and substantial reformation of this RP, without the substitution with
another, but with a progressive shift. In other words, we have at the same time a
serious conceptual novelty (the global structure of the RP changes because of
discoveries not predictable by the previous programme) and a compatibility in
the core with the previous RP [54, 60]. It is neither a superficial maquillage on
marginal points of a hardened structure, nor a radical break with complete substitu-
tion of RP: rather, a steady and irreversible transformation of the architecture of the
previous RP. Particularly, the lines of the reformation seem to be two:
• An extension of the central Neo-Darwinian core, through theoretical and
experimental updating, with in some cases the unexpected reversion to some
“pluralistic” insights of Charles Darwin himself;
• A quite complete substitution of the protective belt, from methodological mono-
factorial postulates to multi-factorial postulates and integrations of patterns.
This transition has “progressive” features and could represent the passage from
MS (the Evolutionary Research Programme 1 – ERP1) to ES (the Evolutionary
Research Programme 2 – ERP2).
4.1 An Extended Neo-Darwinian Core
In this epistemological hypothesis, we see in detail that the core of the ES is today
an “extended Darwinism”, with two interacting “hierarchies” of nested levels: a
genealogical hierarchy of nested levels of transmission of genetic materials
(organisms, populations like “demes”, species, monophyletic taxa); an ecological
An Evolving Research Programme 221
hierarchy of nested levels of transfers of matter and energy (organisms, populations
like “avatars”, local ecosystems, regional ecosystems) [14]. The extended core
includes:
(A) The descriptive domain of evolution intended as factual evidence, that is the
common descent with modifications, the postulate of the continuity of any
evolutionary change, the phylogenetic unit of all living beings, the role of
organisms as basic units of evolution.
(B) The explanatory domain of plural, integrated “patterns” of evolutionary change
(we use the term patterns instead of “models”, because the semantic view, with
its emphasis on families of models as formal description of scientific
theorizing, is clearly inadequate for the evolutionary RP, where models are
useful tools in some fields but not the primary entities of the structure of the
theory itself – [10, 17]); defining “patterns” the repeated schemes (epistemo-
logical and ontological) of historical real events, emerging from scientific
observations, sufficiently general to be considered as “law-like” regularities
in evolution [13], we see specifically:
(B1) Variational patterns: multiple sources of non directed, inheritable varia-
tion, genetic and epigenetic, included the possible inheritance of ecolog-
ical niches; the material basis for evolution and for natural selection is
going to be diversified;
(B2) Selective patterns: Darwinian natural selection and sexual selection,
artificial selection, kin selection, in some cases group selection [58],
briefly multilevel selection [41]; included here all the trade-offs between
these selective processes, and peculiar competitive patterns like meiotic
drive and spermatic competitions;
(B3) Neutralist patterns: the non adaptive domain of the extended core, with
three main sub-patterns: genetic drifts; nearly-neutralist mechanisms in
the genomes, re-assortments and systemic mutations; non selective struc-
tural effects due to genetic constraints (genetic webs, limits to variation),
developmental constraints (Evo-Devo), and physical-chemical constraints
(self-organization);
(B4) Macro-evolutionary patterns: the ecological side of the evolutionary
hierarchy, with all the external, influential macro-evolutionary factors,
able to produce repeated schemes of events like, in a decreasing order of
impact on biological populations: mass extinctions; turnover pulses of
species; rapid adaptive radiations; major evolutionary transitions due to
processes of symbio-genesis [13, 49].
According to this kind of pluralistic core in ERP2, the evolutionary explanation
becomes a way to integrate, case by case, different “patterns”, irreducible one to
another, but compatible one with another, and all needed to cover the heteroge-
neous empirical basis of evolutionary phenomena. The ecological hierarchy
222 T. Pievani
perturbs at different degrees the genealogical one, and the genealogical one
accumulates changes and produces diversity. This multiple core (and the super-
pattern of the relationships between the ecological and the genealogical levels of
evolution) is a candidate framework for the theoretical “unification” of evolutionary
biology [14]. The first patterns (excluded epigenetic inheritance in modern sense),
the second ones (excluded kin selection) and the structural ones are already
Darwinian in their first formulations. The other ones are not originally Darwinian
but compatible and integrative. This is an integrated framework where genealogical
levels and ecological levels coexist and interact, but the Darwinian unit, the
organism (at the same time, genetic replicator and ecologic interactor), and the
Darwinian mechanism, natural selection (as differential survival and reproduction),
remain the fundamental junction of the two hierarchies of levels of change (see the
“sloshing bucket” model of evolution, in [14]).
In this epistemological frame, we clearly understand the dynamics of assimila-
tion and accommodation, and the mix of points of breaking and point of continuity,
in the theoretical challenges above mentioned of Punctuated Equilibria and Neu-
tralism. As restriction of validity, these patterns of the core of ERP2 keep their
explanatory power in natural history until ca. 600 million years ago, that is the
explosive beginnings of organized and individualized Metazoans. For earlier eras,
the patterns could be intended as corroborated explanatory hypotheses, waiting for
more information about the environmental conditions and the kinds of organisms
involved.
This theoretical nucleus represents also an interesting way to depict the unique-
ness of the nature of explanation in evolutionary fields. The probabilistic
generalizations and correlations of evolutionary biology have causal explanations
that do not depend exclusively on the context of the scientific questions (like in
some recent forms of relativistic “contextualism”), but reveal a deeper ecological-
genealogical structure founded on the complementarity of three kinds of
explanations. The explanandum of the theory of evolution is variational (the
diversity of species and variants on Earth, their genealogical relationships, their
transformations) and adaptive (any trait contributing to fitness, the complexity of
structures and behaviors). The architecture of types of explanations is built on three
pillars: (1) functional and selective explanations of the remote causes of emergence
of a trait; (2) structural explanations of the relevance of internal constraints, and
their trade-offs with external pressures; (3) historical and contingent explanations
of chains of causal singular events, and clashes of independent chains of causes,
a priori unpredictable but intelligible a posteriori. Starting from these three
typologies, we can construct a matrix of relationships between the kinds of
explanations: 1 + 2 in the cases of exaptations and trade-off between functions
and structures, analogies and homologies; 1 + 3 in the cases of interferences
between natural selection and Neutralistic processes and macro-evolutionary pro-
cesses; 2 + 3 when Neutralistic processes create structural constraints; 1 + 2 + 3
when we need “total evidence” reconstructions of evolutionary pathways.
An Evolving Research Programme 223
4.2 A Pluralistic Protective Belt
Secondly, the protective belt of the RP becomes more and more pluralistic and
flexible, with a robust diversification of models concerning the rhythms, the units,
the levels and modes of evolution.
Particularly:
• A plurality of rates of evolution and speciation: gradual trends, stasis,
punctuations, plural modes of speciation and changing relative frequencies [13];
• A plurality of units of evolution: group selection; multilevel selection; niche
construction, endo-symbiosis and units organism-niche [41]; where the selection
acts (genomes, organisms, developmental systems, organisms plus niches) and
how (trade-offs between competition and cooperation);
• A plurality of adaptive dynamics and interactions between structures and
functions: frequency of exaptations in natural history; Evo-Devo; modularity;
• A complexity of relationships between levels of evolution: phenotypic plasticity;
evolvability.
In the methodology of RP, the protective belt is subjected to continuous
modifications due to the updating of evidences in surrounding conditions. The
equilibrium between the weights of explanatory power in different patterns is
instable. But what is crucial is that a refutation in the belt, or a radical change in
the perspective of specific debate, does not mean necessarily a problem for the
structure of the core. The belt is the magmatic, ever-changing, constantly refutable
zone of the RP, exposed to external influences and contingencies of the researches.
It could be also possible that an auxiliary pattern in the belt becomes so
important and so diffuse in current evolutionary explanations that it deserves to
be part of the core itself. In absence of strong contrary evidences, and having a good
theoretical stability, it becomes part of the core, like in the case of genetic drifts and
Neutralistic phenomena. So we have an extension of the core, always submitted to
the falsification logics: if you have more patterns in the nucleus, a rival RP has more
possibilities to reach a refutation of some assumptions or to outline a contradiction
between explanations. For that reason, a RP should be not too much minimal and
not too much extended, preserving its structural coherence and avoiding inappro-
priate extensions of the explanandum.
In the passage between ERP1 and ERP2 the heuristic has changed its sign, being
driven now by a programmatic pluralism, in definitions (like “species” and “gene”)
and in explanations (with frequencies of integrated patterns), able to predict a lot of
new facts in several evolutionary disciplines. We observe in literature that the new
heuristic satisfies the criteria of “progressivity”. The assumptions of negligibility
become less influent and the heuristic assumptions highlight the necessity of the
integrations of factors. Conversely, the assumptions of domain and applicability
become more stringent, stressing the opportunity to tune possibly other RPs for
specific adjacent fields (like the evolution of culture – [6, 56]).
224 T. Pievani
5 The Multiple Advantages of the Current Neo-DarwinianPluralism
The change of sign in the heuristic of ERP2 carries a more general epistemological
transition. The standards of evaluation of hypotheses and theories are changing: the
proofs through convergence and consilience of data become more and more
important; we see the birth of originally interdisciplinary lines of researches;
functions, structures and singular histories, mixed together, recover the original
pluralism of the evolutionary explanations.
A new theoretical challenge (as it was the Punctuated Equilibria theory, with its
early “revolutionary” phase and later considerations and pondering about its real
theoretical impact) is not necessarily concerning a marginal epiphenomenon
surrounding a monolithic paradigm or on the contrary a radical crisis of its core.
Otherwise, it could mean a profound extension and revision of its structure,
remaining nevertheless compatible with other components and patterns of it [59].
The result is a structure of the theory of evolution, intended as a RP, more articulated
in a pluralistic frame, more realistic in its assumptions about the currently available
evidences [19, 50], with drastic revision of previous restrictive concept (regarding
the “universality” of some patterns) hardened in the protective belt of ERP1 (or
MS).
The same case could be traced in the history of the idea of “functional
cooptation” in Darwin, then “pre-adaptation” in Ernst Mayr and MS, then in the
more radical sense of “exaptation” [22, 61] and “spandrels” by structural non-
aptations [21]. It is clear in current literature that we do not need a conflation
between standard adaptations and exaptations, but an “extended taxonomy of
fitness” [20] made by three typologies of processes: classical Darwinian adaptations
by natural selection; the functional shift, by natural selection, from a previous
function to a secondary one; spandrels and other side effects with no adaptive
reasons in their beginning, possibly co-opted by natural selection in new external
conditions [46]. Also in this case we have points of breaking with ERP1 (not always
the current utility corresponds to the historical origin) and points of continuity
(natural selection acts, but finding trade-offs with internal constraints of organisms).
So the advantage is double. Firstly, through these epistemological processes of
assimilation and accommodation, we can better appreciate the conceptual tools
involved in the most promising lines of evolutionary research today: for an excel-
lent case, mixing genes, developments and ecological conditions, and considering
all the patterns of evolution (mutations, natural selection, drifts, migration,
hybridization, speciation), see [23]. Secondly, we can understand why one of the
most important scientists involved in the developmental evolutionary biology,
Alessandro Minelli, being conscious of the huge theoretical impact of Evo-Devo
on ERP1 – in terms of conservation of genes families, developmental constraints,
limits to variation, modularity of change, multiple effects, evolvability – neverthe-
less wrote that clearly Evo-Devo “does not offer a significant challenge to the Neo-
Darwinian paradigm” [35]. Evo-Devo likewise extends the conceptual frame of
An Evolving Research Programme 225
Neo-Darwinism and rectifies some previous interpretations (like gene-centrism and
adaptationism) in its surrounding assumptions. The structure of ERP is evolving
towards a more pluralistic version [1].
Furthermore, not less important, this Neo-Lakatosian approach offers some
precious advantages in public debates (frequently hot) concerning evolution and
its debates. The fact that in some points Darwin was wrong, of course, and MS was
inadequate loses a great part of its striking dramatic power. Any RP is an evolving
system, made by patterns, concepts, models, hypotheses, structured in a core (what
is crucial for the survival of the RP) and a protective belt (where nothing is crucial
for the fate of the RP). So a single refutation and an internal contradiction are not
necessarily the end of the world for the theory of evolution, and we need to see the
whole architecture of the RP and how it is rationally changing. A RP is never
falsified by a single observation or anomaly, it could be defeated by a set of new
evidences, new theories, organized in a rival RP [30].
The dynamics of criticism and growth of knowledge is continuous and rational,
with a verifiable internal logics of proofs and refutations, so all the debate around
the alleged “dogmatism” of the “Darwinians” appears like a non sense [48]. Every
aspect of the evolution of ERP is under control and under potential falsification,
even if some parts of the core (the descriptive domain and the major patterns of the
explanatory domain, above described) are so much corroborated that they appear
just like plain evidences without any reasonable doubt [7]. For the same reasons, we
can solve another debate concerning the alleged scenarios “beyond Darwin”, or the
supposed ultimate crisis of Neo-Darwinism: the challenges (frequently interesting
by themselves) evocated as proofs of the imminent death of the “theory” are quite
always debates concerning the protective belt of the RP. So, nothing ultimate, and
moreover criticisms without a rival RP.
But mostly, the methodology here exposed is very useful in the definition of
what is the burden of proof in these debates. If someone wants to demonstrate that
“another theory of evolution” is on the field (like in all the cases in which someone
says that now there would be more “theories of evolution”), he has to prove that:
(1) there is a rival ERP able to explain all the empirical basis of the current one; (2)
this ERP is able to explain something more (it has an additional empirical content,
predictions of new facts, on the basis of other corroborated facts); and it is able to do
1 and 2 using patterns, concepts and principles not reducible to those of the current
one. It is a scheme of rational evaluation (and sophisticated falsificationism) clear
and very fruitful for comparisons between ERPs. Only if we see these three
conditions we can say that a rival RP has defeated a previously dominant one.
We should grant anyone the benefit of doubt, even if the challenge seems to have
nothing to do with science, but of course there is nothing like that rival RP in the
field at the moment.
These and other cases show how the application of the methodology of ERP
could not only represent the ongoing transition between MS and ES very well, but
could also offer valid arguments and epistemological tools of rational analysis in
the never-ending debates that enliven, inside and outside the scientific community,
the developments of the Neo-Darwinian research programme.
226 T. Pievani
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